text:
Computer monitor

A computer monitor is an output device that displays information in pictorial or textual form. A discrete monitor comprises a visual display, support electronics, power supply, housing, electrical connectors, and external user controls.

The display in modern monitors is typically an LCD with LED backlight, having by the 2010s replaced CCFL backlit LCDs. Before the mid-2000s, most monitors used a cathode-ray tube (CRT) as the image output technology. A monitor is typically connected to its host computer via DisplayPort, HDMI, USB-C, DVI, or VGA. Monitors sometimes use other proprietary connectors and signals to connect to a computer, which is less common.

Originally, computer monitors were used for data processing while television sets were used for video. From the 1980s onward, computers (and their monitors) have been used for both data processing and video, while televisions have implemented some computer functionality. In the 2000s, the typical display aspect ratio of both televisions and computer monitors changed from 4:3 to 16:9.

Modern computer monitors are often functionally interchangeable with television sets and vice versa. As most computer monitors do not include integrated speakers, TV tuners, or remote controls, external components such as a DTA box may be needed to use a computer monitor as a TV set.

History
Early electronic computer front panels were fitted with an array of light bulbs where the state of each particular bulb would indicate the on/off state of a particular register bit inside the computer. This allowed the engineers operating the computer to monitor the internal state of the machine, so this panel of lights came to be known as the 'monitor'. As early monitors were only capable of displaying a very limited amount of information and were very transient, they were rarely considered for program output. Instead, a line printer was the primary output device, while the monitor was limited to keeping track of the program's operation.

Computer monitors were formerly known as visual display units (VDU), particularly in British English. This term mostly fell out of use by the 1990s.

Technologies
Multiple technologies have been used for computer monitors. Until the 21st century most used cathode-ray tubes but they have largely been superseded by LCD monitors.

Cathode-ray tube
The first computer monitors used cathode-ray tubes (CRTs). Prior to the advent of home computers in the late 1970s, it was common for a video display terminal (VDT) using a CRT to be physically integrated with a keyboard and other components of the workstation in a single large chassis, typically limiting them to emulation of a paper teletypewriter, thus the early epithet of 'glass TTY'. The display was monochromatic and far less sharp and detailed than on a modern monitor, necessitating the use of relatively large text and severely limiting the amount of information that could be displayed at one time. High-resolution CRT displays were developed for specialized military, industrial and scientific applications but they were far too costly for general use; wider commercial use became possible after the release of a slow, but affordable Tektronix 4010 terminal in 1972.

Some of the earliest home computers (such as the TRS-80 and Commodore PET) were limited to monochrome CRT displays, but color display capability was already a possible feature for a few MOS 6500 series-based machines (such as introduced in 1977 Apple II computer or Atari 2600 console), and the color output was a specialty of the more graphically sophisticated Atari 8-bit computers, introduced in 1979. Either computer could be connected to the antenna terminals of an ordinary color TV set or used with a purpose-made CRT color monitor for optimum resolution and color quality. Lagging several years behind, in 1981 IBM introduced the Color Graphics Adapter, which could display four colors with a resolution of pixels, or it could produce  pixels with two colors. In 1984 IBM introduced the Enhanced Graphics Adapter which was capable of producing 16 colors and had a resolution of.

By the end of the 1980s color progressive scan CRT monitors were widely available and increasingly affordable, while the sharpest prosumer monitors could clearly display high-definition video, against the backdrop of efforts at HDTV standardization from the 1970s to the 1980s failing continuously, leaving consumer SDTVs to stagnate increasingly far behind the capabilities of computer CRT monitors well into the 2000s. During the following decade, maximum display resolutions gradually increased and prices continued to fall as CRT technology remained dominant in the PC monitor market into the new millennium, partly because it remained cheaper to produce. CRTs still offer color, grayscale, motion, and latency advantages over today's LCDs, but improvements to the latter have made them much less obvious. The dynamic range of early LCD panels was very poor, and although text and other motionless graphics were sharper than on a CRT, an LCD characteristic known as pixel lag caused moving graphics to appear noticeably smeared and blurry.

Liquid-crystal display
There are multiple technologies that have been used to implement liquid-crystal displays (LCD). Throughout the 1990s, the primary use of LCD technology as computer monitors was in laptops where the lower power consumption, lighter weight, and smaller physical size of LCDs justified the higher price versus a CRT. Commonly, the same laptop would be offered with an assortment of display options at increasing price points: (active or passive) monochrome, passive color, or active matrix color (TFT). As volume and manufacturing capability have improved, the monochrome and passive color technologies were dropped from most product lines.

TFT-LCD is a variant of LCD which is now the dominant technology used for computer monitors.

The first standalone LCDs appeared in the mid-1990s selling for high prices. As prices declined they became more popular, and by 1997 were competing with CRT monitors. Among the first desktop LCD computer monitors were the Eizo FlexScan L66 in the mid-1990s, the SGI 1600SW, Apple Studio Display and the ViewSonic VP140 in 1998. In 2003, LCDs outsold CRTs for the first time, becoming the primary technology used for computer monitors. The physical advantages of LCD over CRT monitors are that LCDs are lighter, smaller, and consume less power. In terms of performance, LCDs produce less or no flicker, reducing eyestrain, sharper image at native resolution, and better checkerboard contrast. On the other hand, CRT monitors have superior blacks, viewing angles, and response time, can use arbitrary lower resolutions without aliasing, and flicker can be reduced with higher refresh rates, though this flicker can also be used to reduce motion blur compared to less flickery displays such as most LCDs. Many specialized fields such as vision science remain dependent on CRTs, the best LCD monitors having achieved moderate temporal accuracy, and so can be used only if their poor spatial accuracy is unimportant.

High dynamic range (HDR) has been implemented into high-end LCD monitors to improve grayscale accuracy. Since around the late 2000s, widescreen LCD monitors have become popular, in part due to television series, motion pictures and video games transitioning to widescreen, which makes squarer monitors unsuited to display them correctly.

Organic light-emitting diode
Organic light-emitting diode (OLED) monitors provide most of the benefits of both LCD and CRT monitors with few of their drawbacks, though much like plasma panels or very early CRTs they suffer from burn-in, and remain very expensive.

Measurements of performance
The performance of a monitor is measured by the following parameters:

 * Display geometry:
 * Viewable image size - is usually measured diagonally, but the actual widths and heights are more informative since they are not affected by the aspect ratio in the same way. For CRTs, the viewable size is typically 1 in smaller than the tube itself.
 * Aspect ratio - is the ratio of the horizontal length to the vertical length. Monitors usually have the aspect ratio 4:3, 5:4, 16:10 or 16:9.
 * Radius of curvature (for curved monitors) - is the radius that a circle would have if it had the same curvature as the display. This value is typically given in millimeters, but expressed with the letter "R" instead of a unit (for example, a display with "3800R curvature" has a 3800mm radius of curvature.
 * Display resolution is the number of distinct pixels in each dimension that can be displayed natively. For a given display size, maximum resolution is limited by dot pitch or DPI.
 * Dot pitch represents the distance between the primary elements of the display, typically averaged across it in nonuniform displays. A related unit is pixel pitch, In LCDs, pixel pitch is the distance between the center of two adjacent pixels. In CRTs, pixel pitch is defined as the distance between subpixels of the same color. Dot pitch is the reciprocal of pixel density.
 * Pixel density is a measure of how densely packed the pixels on a display are. In LCDs, pixel density is the number of pixels in one linear unit along the display, typically measured in pixels per inch (px/in or ppi).

 * Color characteristics:
 * Luminance - measured in candelas per square meter (cd/m$2$, also called a nit).
 * Contrast ratio is the ratio of the luminosity of the brightest color (white) to that of the darkest color (black) that the monitor is capable of producing simultaneously. For example, a ratio of means that the brightest shade (white) is 20,000 times brighter than its darkest shade (black). Dynamic contrast ratio is measured with the LCD backlight turned off. ANSI contrast is with both black and white simultaneously adjacent onscreen.
 * Color depth - measured in bits per primary color or bits for all colors. Those with 10bpc (bits per channel) or more can display more shades of color (approximately 1 billion shades) than traditional 8bpc monitors (approximately 16.8 million shades or colors), and can do so more precisely without having to resort to dithering.
 * Gamut - measured as coordinates in the CIE 1931 color space. The names sRGB or Adobe RGB are shorthand notations.
 * Color accuracy - measured in ΔE (delta-E); the lower the ΔE, the more accurate the color representation. A ΔE of below 1 is imperceptible to the human eye. A ΔE of 2–4 is considered good and requires a sensitive eye to spot the difference.
 * Viewing angle is the maximum angle at which images on the monitor can be viewed, without subjectively excessive degradation to the image. It is measured in degrees horizontally and vertically.
 * Input speed characteristics:
 * Refresh rate is (in CRTs) the number of times in a second that the display is illuminated (the number of times a second a raster scan is completed). In LCDs it is the number of times the image can be changed per second, expressed in hertz (Hz). Determines the maximum number of frames per second (FPS) a monitor is capable of showing. Maximum refresh rate is limited by response time.
 * Response time is the time a pixel in a monitor takes to change between two shades. The particular shades depend on the test procedure, which differs between manufacturers. In general, lower numbers mean faster transitions and therefore fewer visible image artifacts such as ghosting. Grey to grey (GtG), measured in milliseconds (ms).
 * Input latency is the time it takes for a monitor to display an image after receiving it, typically measured in milliseconds (ms).
 * Power consumption is measured in watts.

Size
On two-dimensional display devices such as computer monitors the display size or viewable image size is the actual amount of screen space that is available to display a picture, video or working space, without obstruction from the bezel or other aspects of the unit's design. The main measurements for display devices are width, height, total area and the diagonal.

The size of a display is usually given by manufacturers diagonally, i.e. as the distance between two opposite screen corners. This method of measurement is inherited from the method used for the first generation of CRT television when picture tubes with circular faces were in common use. Being circular, it was the external diameter of the glass envelope that described their size. Since these circular tubes were used to display rectangular images, the diagonal measurement of the rectangular image was smaller than the diameter of the tube's face (due to the thickness of the glass). This method continued even when cathode-ray tubes were manufactured as rounded rectangles; it had the advantage of being a single number specifying the size and was not confusing when the aspect ratio was universally 4:3.

With the introduction of flat panel technology, the diagonal measurement became the actual diagonal of the visible display. This meant that an eighteen-inch LCD had a larger viewable area than an eighteen-inch cathode-ray tube.

Estimation of monitor size by the distance between opposite corners does not take into account the display aspect ratio, so that for example a 16:9 21 in widescreen display has less area, than a 21 in 4:3 screen. The 4:3 screen has dimensions of 16.8 × and an area 211 sqin, while the widescreen is 18.3 ×, 188 sqin.

Aspect ratio
Until about 2003, most computer monitors had a 4:3 aspect ratio and some had 5:4. Between 2003 and 2006, monitors with 16:9 and mostly 16:10 (8:5) aspect ratios became commonly available, first in laptops and later also in standalone monitors. Reasons for this transition included productive uses (i.e. field of view in video games and movie viewing) such as the word processor display of two standard letter pages side by side, as well as CAD displays of large-size drawings and application menus at the same time. In 2008 16:10 became the most common sold aspect ratio for LCD monitors and the same year 16:10 was the mainstream standard for laptops and notebook computers.

In 2010, the computer industry started to move over from 16:10 to 16:9 because 16:9 was chosen to be the standard high-definition television display size, and because they were cheaper to manufacture.

In 2011, non-widescreen displays with 4:3 aspect ratios were only being manufactured in small quantities. According to Samsung, this was because the "Demand for the old 'Square monitors' has decreased rapidly over the last couple of years," and "I predict that by the end of 2011, production on all 4:3 or similar panels will be halted due to a lack of demand."

Resolution
The resolution for computer monitors has increased over time. From during the late 1970s, to  during the late 1990s. Since 2009, the most commonly sold resolution for computer monitors is, shared with the 1080p of HDTV. Before 2013 mass market LCD monitors were limited to at 30 in, excluding niche professional monitors. By 2015 most major display manufacturers had released (4K UHD) displays, and the first  (8K) monitors had begun shipping.

Gamut
Every RGB monitor has its own color gamut, bounded in chromaticity by a color triangle. Some of these triangles are smaller than the sRGB triangle, some are larger. Colors are typically encoded by 8 bits per primary color. The RGB value [255, 0, 0] represents red, but slightly different colors in different color spaces such as Adobe RGB and sRGB. Displaying sRGB-encoded data on wide-gamut devices can give an unrealistic result. The gamut is a property of the monitor; the image color space can be forwarded as Exif metadata in the picture. As long as the monitor gamut is wider than the color space gamut, correct display is possible, if the monitor is calibrated. A picture that uses colors that are outside the sRGB color space will display on an sRGB color space monitor with limitations. Still today, many monitors that can display the sRGB color space are not factory nor user-calibrated to display it correctly. Color management is needed both in electronic publishing (via the Internet for display in browsers) and in desktop publishing targeted to print.

Universal features

 * Power saving

Most modern monitors will switch to a power-saving mode if no video-input signal is received. This allows modern operating systems to turn off a monitor after a specified period of inactivity. This also extends the monitor's service life. Some monitors will also switch themselves off after a time period on standby.

Most modern laptops provide a method of screen dimming after periods of inactivity or when the battery is in use. This extends battery life and reduces wear.

 * Indicator light

Most modern monitors have two different indicator light colors wherein if video-input signal was detected, the indicator light is green and when the monitor is in power-saving mode, the screen is black and the indicator light is orange. Some monitors have different indicator light colors and some monitors have a blinking indicator light when in power-saving mode.

 * Integrated accessories

Many monitors have other accessories (or connections for them) integrated. This places standard ports within easy reach and eliminates the need for another separate hub, camera, microphone, or set of speakers. These monitors have advanced microprocessors which contain codec information, Windows interface drivers and other small software which help in proper functioning of these functions.

 * Ultrawide screens

Monitors that feature an aspect ratio greater than 2:1 (for instance, 21:9 or 32:9, as opposed to the more common 16:9, which resolves to 1.7$\overline{7}$:1).Monitors with an aspect ratio greater than 3:1 are marketed as super ultrawide monitors. These are typically massive curved screens intended to replace a multi-monitor deployment.

 * Touch screen

These monitors use touching of the screen as an input method. Items can be selected or moved with a finger, and finger gestures may be used to convey commands. The screen will need frequent cleaning due to image degradation from fingerprints.

 * Sensors

 * Ambient light for automatically adjusting screen brightness and/or color temperature
 * Infrared camera for biometrics, eye and/or face recognition. Eye tracking as user input device. As lidar receiver for 3D scanning.

Consumer features

 * Glossy screen

Some displays, especially newer flat panel monitors, replace the traditional anti-glare matte finish with a glossy one. This increases color saturation and sharpness but reflections from lights and windows are more visible. Anti-reflective coatings are sometimes applied to help reduce reflections, although this only partly mitigates the problem.

 * Curved designs

Most often using nominally flat-panel display technology such as LCD or OLED, a concave rather than convex curve is imparted, reducing geometric distortion, especially in extremely large and wide seamless desktop monitors intended for close viewing range.

 * 3D

Newer monitors are able to display a different image for each eye, often with the help of special glasses and polarizers, giving the perception of depth. An autostereoscopic screen can generate 3D images without headgear.

Professional features

 * Anti-glare and anti-reflection screens

Features for medical using or for outdoor placement.

 * Directional screen

Narrow viewing angle screens are used in some security-conscious applications.

 * Integrated professional accessories

Integrated screen calibration tools, screen hoods, signal transmitters; Protective screens.

 * Tablet screens

A combination of a monitor with a graphics tablet. Such devices are typically unresponsive to touch without the use of one or more special tools' pressure. Newer models however are now able to detect touch from any pressure and often have the ability to detect tool tilt and rotation as well.

Touch and tablet sensors are often used on sample and hold displays such as LCDs to substitute for the light pen, which can only work on CRTs.

 * Integrated display LUT and 3D LUT tables

The option for using the display as a reference monitor; these calibration features can give an advanced color management control for take a near-perfect image.

 * Local dimming backlight

Option for professional LCD monitors, inherent to OLED & CRT; professional feature with mainstream tendency.

 * Backlight brightness/color uniformity compensation

Near to mainstream professional feature; advanced hardware driver for backlit modules with local zones of uniformity correction.

Mounting
Computer monitors are provided with a variety of methods for mounting them depending on the application and environment.

Raw monitor
Raw monitors are raw framed LCD monitors, to install a monitor on a not so common place, ie, on the car door or you need it in the trunk. It is usually paired with a power adapter to have a versatile monitor for home or commercial use.

Desktop
A desktop monitor is typically provided with a stand from the manufacturer which lifts the monitor up to a more ergonomic viewing height. The stand may be attached to the monitor using a proprietary method or may use, or be adaptable to, a VESA mount. A VESA standard mount allows the monitor to be used with more after-market stands if the original stand is removed. Stands may be fixed or offer a variety of features such as height adjustment, horizontal swivel, and landscape or portrait screen orientation.

VESA mount
The Flat Display Mounting Interface (FDMI), also known as VESA Mounting Interface Standard (MIS) or colloquially as a VESA mount, is a family of standards defined by the Video Electronics Standards Association for mounting flat panel displays to stands or wall mounts. It is implemented on most modern flat-panel monitors and TVs.

For computer monitors, the VESA Mount typically consists of four threaded holes on the rear of the display that will mate with an adapter bracket.

Rack mount
Rack mount computer monitors are available in two styles and are intended to be mounted into a 19-inch rack:

A fixed rack mount monitor is mounted directly to the rack with the flat-panel or CRT visible at all times. The height of the unit is measured in rack units (RU) and 8U or 9U are most common to fit 17-inch or 19-inch screens. The front sides of the unit are provided with flanges to mount to the rack, providing appropriately spaced holes or slots for the rack mounting screws. A 19-inch diagonal screen is the largest size that will fit within the rails of a 19-inch rack. Larger flat-panels may be accommodated but are 'mount-on-rack' and extend forward of the rack. There are smaller display units, typically used in broadcast environments, which fit multiple smaller screens side by side into one rack mount.
 * Fixed

A stowable rack mount monitor is 1U, 2U or 3U high and is mounted on rack slides allowing the display to be folded down and the unit slid into the rack for storage as a drawer. The flat display is visible only when pulled out of the rack and deployed. These units may include only a display or may be equipped with a keyboard creating a KVM (Keyboard Video Monitor). Most common are systems with a single LCD but there are systems providing two or three displays in a single rack mount system.
 * Stowable

Panel mount
A panel mount computer monitor is intended for mounting into a flat surface with the front of the display unit protruding just slightly. They may also be mounted to the rear of the panel. A flange is provided around the screen, sides, top and bottom, to allow mounting. This contrasts with a rack mount display where the flanges are only on the sides. The flanges will be provided with holes for thru-bolts or may have studs welded to the rear surface to secure the unit in the hole in the panel. Often a gasket is provided to provide a water-tight seal to the panel and the front of the screen will be sealed to the back of the front panel to prevent water and dirt contamination.

Open frame
An open frame monitor provides the display and enough supporting structure to hold associated electronics and to minimally support the display. Provision will be made for attaching the unit to some external structure for support and protection. Open frame monitors are intended to be built into some other piece of equipment providing its own case. An arcade video game would be a good example with the display mounted inside the cabinet. There is usually an open frame display inside all end-use displays with the end-use display simply providing an attractive protective enclosure. Some rack mount monitor manufacturers will purchase desktop displays, take them apart, and discard the outer plastic parts, keeping the inner open-frame display for inclusion into their product.

Security vulnerabilities
According to an NSA document leaked to Der Spiegel, the NSA sometimes swaps the monitor cables on targeted computers with a bugged monitor cable in order to allow the NSA to remotely see what is being displayed on the targeted computer monitor.

Van Eck phreaking is the process of remotely displaying the contents of a CRT or LCD by detecting its electromagnetic emissions. It is named after Dutch computer researcher Wim van Eck, who in 1985 published the first paper on it, including proof of concept. Phreaking more generally is the process of exploiting telephone networks.

title: Computer monitor


text:
Talk:Computer monitor

Organic light-emitting diode
Seems out of date? Surely LED screens are the most common in use now days? Bill W102102 (talk) 06:26, 20 August 2022 (UTC)
 * OLED is not in common use. — Glenwing (talk) 06:44, 20 August 2022 (UTC)

Visual display unit vs. computer monitor
Visual display unit redirects here; this was done around 2009, when CRT monitors were still in somewhat common use. There was perhaps some confusion with the very similar term Video display unit (that latter term, which unlike the former, to me implies only raster displays but not vector displays) and the parent of both, Electronic visual display. There are analog and digital versions of each, of course.

Are there other uses (current and/or historical) of that term (e.g. for radar display screens connected pre-computer analog RADAR systems) that would justify either (at least a stub) article or a disambiguation page at VDU / Visual display unit?

(FYI, Talk:Visual display unit redirects here, to Talk:Computer monitor; See also: Talk:Video display unit and Talk:Electronic visual display)

- Jim Grisham (talk) 23:30, 5 September 2022 (UTC)

"Video screen" listed at Redirects for discussion
An editor has identified a potential problem with the redirect Video screen and has thus listed it for discussion. This discussion will occur at Redirects for discussion/Log/2022 October 5 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Steel1943 (talk) 05:50, 5 October 2022 (UTC)

"Visual display unit" listed at Redirects for discussion
An editor has identified a potential problem with the redirect Visual display unit and has thus listed it for discussion. This discussion will occur at Redirects for discussion/Log/2022 October 8 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Steel1943 (talk) 01:38, 9 October 2022 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Talk:Computer monitor


text:
ClearType

ClearType is Microsoft's implementation of subpixel rendering technology in rendering text in a font system. ClearType attempts to improve the appearance of text on certain types of computer display screens by sacrificing color fidelity for additional intensity variation. This trade-off is asserted to work well on LCD flat panel monitors.

ClearType was first announced at the November 1998 COMDEX exhibition. The technology was first introduced in software in January 2000 as an always-on feature of Microsoft Reader, which was released to the public in August 2000.

ClearType was significantly changed with the introduction of DirectWrite in Windows 7.

With the increasing availability of HiDPI displays after 2012, subpixel rendering has become less necessary.

Background
Computer displays where the positions of individual pixels are permanently fixed – such as most modern flat panel displays –  can show saw-tooth edges when displaying small, high-contrast graphic elements, such as text. ClearType uses spatial anti-aliasing at the subpixel level to reduce visible artifacts on such displays when text is rendered, making the text appear "smoother" and less jagged. ClearType also uses very heavy font hinting to force the font to fit into the pixel grid. This increases edge contrast and readability of small fonts at the expense of font rendering fidelity and has been criticized by graphic designers for making different fonts look similar.

Like most other types of subpixel rendering, ClearType involves a compromise, sacrificing one aspect of image quality (color or chrominance detail) for another (light and dark or luminance detail). The compromise can improve text appearance when luminance detail is more important than chrominance.

Only user and system applications render the application of ClearType. ClearType does not alter other graphic display elements (including text already in bitmaps). For example, ClearType enhancement renders text on the screen in Microsoft Word, but text placed in a bitmapped image in a program such as Adobe Photoshop is not. In theory, the method (called "RGB Decimation" internally) can enhance the anti-aliasing of any digital image.

ClearType was invented in the Microsoft e-Books team by Bert Keely and Greg Hitchcock. It was then analyzed by researchers in the company, and signal processing expert John Platt designed an improved version of the algorithm. Dick Brass, a Vice President at Microsoft from 1997 to 2004, complained that the company was slow in moving ClearType to market in the portable computing field.

Human vision and cognition
ClearType and similar technologies work on the theory that variations in intensity are more noticeable than variations in color.

Expert opinion
In a MSDN article, Microsoft acknowledges that "[te]xt that is rendered with ClearType can also appear significantly different when viewed by individuals with varying levels of color sensitivity. Some individuals can detect slight differences in color better than others." This opinion is shared by font designer Thomas Phinney (former CEO of FontLab, also formerly with Adobe Systems ): "There is also considerable variation between individuals in their sensitivity to color fringing. Some people just notice it and are bothered by it a lot more than others." Software developer Melissa Elliott has written about finding ClearType rendering uncomfortable to read, saying that "instead of seeing black text, I see blue text, and rendered over it but offset by a pixel or two, I see orange text, and someone reached into a bag of purple pixel glitter and just tossed it on...I’m not the only person in the world with this problem, and yet, every time it comes up, people are quick to assure me it works for them as if that’s supposed to make me feel better."

Hinting expert Beat Stamm, who worked on ClearType at Microsoft, agrees that ClearType may look blurry at 96 dpi, which was a typical resolution for LCDs in 2008, but adds that higher resolution displays improve on this aspect: "WPF [Windows Presentation Foundation] uses method C [ClearType with fractional pixel positioning ], but few display devices have a sufficiently high resolution to make the potential blur a moot point for everybody. . . . Some people are ok with the blur in Method C, some aren’t. Anecdotal evidence suggests that some people are fine with Method C when reading continuous text at 96 dpi (e.g. Times Reader, etc.) but not in UI scenarios. Many people are fine with the colors of ClearType, even at 96 dpi, but a few aren’t… To my eyes and at 96 dpi, Method C doesn’t read as well as Method A. It reads “blurrily” to me. Conversely, at 144 dpi, I don’t see a problem with Method C. It looks and reads just fine to me." One illustration of the potential problem is the following image:

In the above block of text, the same portion of text is shown in the upper half without and in the lower half with ClearType rendering (as opposed to Standard and ClearType in the previous image). This and the previous example with the orange circle demonstrate the blurring introduced.

Empirical studies
A 2001 study, conducted by researchers from Clemson University and The University of Pennsylvania on "18 users who spent 60 minutes reading fiction from each of three different displays" found that "When reading from an LCD display, users preferred text rendered with ClearType. ClearType also yielded higher readability judgments and lower ratings of mental fatigue." A 2002 study on 24 users conducted by the same researchers from Clemson University also found that "Participants were significantly more accurate at identifying words with ClearType than without ClearType."

According to a 2006 study, at the University of Texas at Austin by Dillon et al., ClearType "may not be universally beneficial". The study notes that maximum benefit may be seen when the information worker is spending large proportions of their time reading text (which is not necessarily the case for the majority of computer users today). Additionally, over one third of the study participants experienced some disadvantage when using ClearType. Whether ClearType, or other rendering, should be used is very subjective and it must be the choice of the individual, with the report recommending "to allow users to disable [ClearType] if they find it produces effects other than improved performance".

Another 2007 empirical study, found that "while ClearType rendering does not improve text legibility, reading speed or comfort compared to perceptually-tuned grayscale rendering, subjects prefer text with moderate ClearType rendering to text with grayscale or higher-level ClearType contrast."

A 2007 survey, of the literature by Microsoft researcher Kevin Larson presented a different picture: "Peer-reviewed studies have consistently found that using ClearType boosts reading performance compared with other text-rendering systems. In a 2004 study, for instance, Lee Gugerty, a psychology professor at Clemson University, in South Carolina, measured a 17 percent improvement in word recognition accuracy with ClearType. Gugerty’s group also showed, in a sentence comprehension study, that ClearType boosted reading speed by 5 percent and comprehension by 2 percent. Similarly, in a study published in 2007, psychologist Andrew Dillon at the University of Texas at Austin found that when subjects were asked to scan a spreadsheet and pick out certain information, they did those tasks 7 percent faster with ClearType."

Display requirements
ClearType and allied technologies require display hardware with fixed pixels and subpixels. More precisely, the positions of the pixels and subpixels on the screen must be exactly known to the computer to which it is connected. This is the case for flat-panel displays, on which the positions of the pixels are permanently fixed by the design of the screen itself. Almost all flat panels have a perfectly rectangular array of square pixels, each of which contains three rectangular subpixels in the three primary colors, with the normal ordering being red, green, and blue, arranged in vertical bands. ClearType assumes this arrangement of pixels when rendering text.

ClearType does not work properly with flat-panel displays that are operated at resolutions other than their “native” resolutions, since only the native resolution corresponds exactly to the actual positions of pixels on the screen of the display.

If a display does not have the type of fixed pixels that ClearType expects, text rendered with ClearType enabled actually looks worse than type rendered without it. Some flat panels have unusual pixel arrangements, with the colors in a different order, or with the subpixels positioned differently (in three horizontal bands, or in other ways). ClearType needs to be manually tuned for use with such displays (see below).

ClearType will not work as intended on displays that have no fixed pixel positions, such as CRT displays (which were still prevalent at the time of the release of Windows XP, which is why ClearType is disabled by default), however it will still have some antialiasing effect and may be preferable to some users as compared to non-anti-aliased type.

Sensitivity to display orientation
Because ClearType utilizes the physical layout of the red, green and blue pigments of the LCD screen, it is sensitive to the orientation of the display.

ClearType in Windows XP supports the RGB and BGR sub pixel structures; rotated displays, in which the subpixels are stacked vertically rather than arranged horizontally, are not supported. Using ClearType on these display configurations will actually reduce the display quality. The best option for users of Windows XP having rotated LCD displays (Tablet PCs or swivel-stand LCD displays) is using regular anti-aliasing, or switching off font-smoothing altogether.

The software developer documentation for Windows CE states that ClearType for rotated screens is supported on that platform.

Implementations

 * Windows XP (off by default)
 * Windows Vista (on by default)
 * Windows 7 (on by default)
 * Windows 8: Only used in Windows 8 Desktop and all desktop apps
 * Windows 10: Only used in Win32 apps and Win32 system features, not Universal Windows Platform.
 * Internet Explorer 7 and later (on by default)
 * Microsoft Office 2007 and 2010 (on by default)
 * Windows Live Messenger (on by default)
 * Microsoft Reader

ClearType is also an integrated component of the Windows Presentation Foundation text-rendering engine.

ClearType Font Collection
As part of the Vista release, Microsoft released a set of fonts, known as the ClearType Font Collection, thought to work well with the ClearType system:
 * Calibri
 * Cambria
 * Candara
 * Consolas
 * Constantia
 * Corbel
 * Meiryo

Fonts included by some, but not always part of the set:
 * Cariadings
 * Malgun Gothic
 * Microsoft JhengHei
 * Microsoft YaHei
 * Segoe

ClearType in GDI
ClearType can be globally enabled or disabled for GDI applications. A control panel applet is available to let the users tune the GDI ClearType settings. The GDI implementation of ClearType does not support sub-pixel positioning.

ClearType tuning
Windows XP, as supplied, allow ClearType to be turned on or off, with no adjustment; Windows 7 and later allow tuning of the ClearType parameters in Control Panel. A Microsoft ClearType tuner utility is available for free download for Windows versions lacking this facility. If ClearType is disabled in the operating system, applications with their own ClearType controls can still support it. Microsoft Reader (for e-books) has its own ClearType tuner.

ClearType in WPF
All text in Windows Presentation Foundation is anti-aliased and rendered using ClearType. There are separate ClearType registry settings for GDI and WPF applications, but by default the WPF entries are absent, and the GDI values are used in their absence. WPF registry entries can be tuned using the instructions from the MSDN WPF Text Blog.

ClearType in WPF supports sub-pixel positioning, natural advance widths, Y-direction anti-aliasing and hardware acceleration. WPF supports aggressive caching of pre-rendered ClearType text in video memory. The extent to which this is supported is dependent on the video card. DirectX 10 cards will be able to cache the font glyphs in video memory, then perform the composition (assembling of character glyphs in the correct order, with the correct spacing), alpha blending (application of anti-aliasing), and RGB blending (ClearType's sub-pixel color calculations), entirely in hardware. This means that only the original glyphs need to be stored in video memory once per font (Microsoft estimates that this would require 2 MB of video memory per font), and other operations such as the display of anti-aliased text on top of other graphics – including video –  can also be done with no computation effort on the part of the CPU. DirectX 9 cards will only be able to cache the alpha-blended glyphs in memory, thus requiring the CPU to handle glyph composition and alpha-blending before passing this to the video card. Caching these partially rendered glyphs requires significantly more memory (Microsoft estimates 5 MB per process). Cards that don't support DirectX 9 have no hardware-accelerated text rendering capabilities.

ClearType in DirectWrite
As pixel densities of displays improved and more high DPI screens became available, colored subpixel rendering became less of a necessity according to Microsoft. Also Windows tablet user interfaces evolved to support vertical screen orientations where the LCD color stripes would run horizontally. The original colored ClearType subpixel rendering was tuned to work optimally with horizontal orientation LCD displays where RGB or BGR stripes run vertically. For these reasons, DirectWrite which is the next-generation text rendering API from Microsoft moved away from color-aware ClearType. The font rendering engine in DirectWrite supports a different version of ClearType with only greyscale anti-aliasing, not color subpixel rendering, as demonstrated at PDC 2008. This version is sometimes called Natural ClearType but is often referred to simply as DirectWrite rendering (with the term "ClearType" being designated to only the RGB/BGR color subpixel rendering version). The improvements have been confirmed by independent sources, such as Firefox developers; they were particularly noticeable for OpenType fonts in Compact Font Format (CFF).

Many Office 2013 apps including Word 2013, Excel 2013, parts of Outlook 2013 stopped using ClearType and switched to this DirectWrite greyscale antialiasing. The reasons invoked are, in the words of Murray Sargent: "There is a problem with ClearType: it depends critically on the color of the background pixels. This isn’t a problem if you know a priori that those pixels are white, which is usually the case for text. But the general case involves calculating what the colors should be for an arbitrary background and that takes time. Meanwhile, Word 2013 enjoys cool animations and smooth zooming. Nothing jumps any more. Even the caret (the blinking vertical line at the text insertion point) glides from one position to the next as you type. Jerking movement just isn’t considered cool any more. Well animations and zooms have to be faster than human response times in order to appear smooth. And that rules out ClearType in animated scenarios at least with present generation hardware. And in future scenarios, screens will have sufficiently high resolution that gray-scale anti-aliasing should suffice."

For the same reasons related to animation performance and vertical screen orientations where the colored RGB/BGR ClearType antialiasing would be a problem, the color-aware version of ClearType was abandoned in Metro-style apps platform of Windows 8 (and Universal Windows Platform of Windows 10)., including the Start menu and everything not using classic Win32 APIs (GDI/GDI+).

Patents
ClearType is a registered trademark and Microsoft claims protection under the following U.S. patents, all expired:

 * Subpixel rendering:
 * – Method and apparatus for displaying images such as text
 * – Mapping image data samples to pixel sub-components on a striped display device
 * – Weighted mapping of image data samples to pixel sub-components on a display device
 * – Methods and apparatus for performing image rendering and rasterization operations
 * Complex color filtering:
 * – Mapping samples of foreground/background color image data to pixel sub-components
 * – Method and apparatus for detecting and reducing color artifacts in images
 * – Methods apparatus and data structures for enhancing the resolution of images to be rendered on patterned display devices
 * – Filtering image data to obtain samples mapped to pixel sub-components of a display device
 * – Filtering image data to obtain samples mapped to pixel sub-components of a display device
 * Subpixel font hinting and layout:
 * – Methods and apparatus for performing grid fitting and hinting operations
 * – Maintaining advance widths of existing characters that have been resolution enhanced
 * ClearType tuning:
 * – Method and apparatus for improving the quality of displayed images through the use of user reference information

Other uses of the ClearType brand
The ClearType name was also used to refer to the screens of Microsoft Surface tablets. ClearType HD Display indicates a 1366×768 screen, while ClearType Full HD Display indicates a 1920×1080 screen.

title: ClearType


text:
Centriole

In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells, but are not present in conifers (Pinophyta), flowering plants (angiosperms) and most fungi, and are only present in the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and Ginkgo. A bound pair of centrioles, surrounded by a highly ordered mass of dense material, called the pericentriolar material (PCM), makes up a structure called a centrosome.

Centrioles are typically made up of nine sets of short microtubule triplets, arranged in a cylinder. Deviations from this structure include crabs and Drosophila melanogaster embryos, with nine doublets, and Caenorhabditis elegans sperm cells and early embryos, with nine singlets. Additional proteins include centrin, cenexin and tektin.

The main function of centrioles is to produce cilia during interphase and the aster and the spindle during cell division.

History
The centrosome was discovered jointly by Walther Flemming in 1875 and Edouard Van Beneden in 1876. Edouard Van Beneden made the first observation of centrosomes as composed of two orthogonal centrioles in 1883. Theodor Boveri introduced the term "centrosome" in 1888  and the term "centriole" in 1895. The basal body was named by Theodor Wilhelm Engelmann in 1880. The pattern of centriole duplication was first worked out independently by Étienne de Harven and Joseph G. Gall c. 1950.

Role in cell division
Centrioles are involved in the organization of the mitotic spindle and in the completion of cytokinesis. Centrioles were previously thought to be required for the formation of a mitotic spindle in animal cells. However, more recent experiments have demonstrated that cells whose centrioles have been removed via laser ablation can still progress through the G1 stage of interphase before centrioles can be synthesized later in a de novo fashion. Additionally, mutant flies lacking centrioles develop normally, although the adult flies' cells lack flagella and cilia and as a result, they die shortly after birth. The centrioles can self replicate during cell division.

Cellular organization
Centrioles are a very important part of centrosomes, which are involved in organizing microtubules in the cytoplasm. The position of the centriole determines the position of the nucleus and plays a crucial role in the spatial arrangement of the cell.

Fertility
Sperm centrioles are important for 2 functions: (1) to form the sperm flagellum and sperm movement and (2) for the development of the embryo after fertilization. The sperm supplies the centriole that creates the centrosome and microtubule system of the zygote.

Ciliogenesis
In flagellates and ciliates, the position of the flagellum or cilium is determined by the mother centriole, which becomes the basal body. An inability of cells to use centrioles to make functional flagella and cilia has been linked to a number of genetic and developmental diseases. In particular, the inability of centrioles to properly migrate prior to ciliary assembly has recently been linked to Meckel–Gruber syndrome.

Animal development
Proper orientation of cilia via centriole positioning toward the posterior of embryonic node cells is critical for establishing left-right asymmetry, during mammalian development.

Centriole duplication
Before DNA replication, cells contain two centrioles, an older mother centriole, and a younger daughter centriole. During cell division, a new centriole grows at the proximal end of both mother and daughter centrioles. After duplication, the two centriole pairs (the freshly assembled centriole is now a daughter centriole in each pair) will remain attached to each other orthogonally until mitosis. At that point the mother and daughter centrioles separate dependently on an enzyme called separase.

The two centrioles in the centrosome are tied to one another. The mother centriole has radiating appendages at the distal end of its long axis and is attached to its daughter at the proximal end. Each daughter cell formed after cell division will inherit one of these pairs. Centrioles start duplicating when DNA replicates.

Origin
The last common ancestor of all eukaryotes was a ciliated cell with centrioles. Some lineages of eukaryotes, such as land plants, do not have centrioles except in their motile male gametes. Centrioles are completely absent from all cells of conifers and flowering plants, which do not have ciliate or flagellate gametes. It is unclear if the last common ancestor had one or two cilia. Important genes such as centrins required for centriole growth, are only found in eukaryotes, and not in bacteria or archaea.

Etymology and pronunciation
The word centriole uses combining forms of centri- and -ole, yielding "little central part", which describes a centriole's typical location near the center of the cell.

Atypical centrioles
Typical centrioles are made of 9 triplets of microtubules organized with radial symmetry. Centrioles can vary the number of microtubules and can be made of 9 doublets of microtubules (as in Drosophila melanogaster) or 9 singlets of microtubules as in C. elegans. Atypical centrioles are centrioles that do not have microtubules, such as the Proximal Centriole-Like found in D. melanogaster sperm, or that have microtubules with no radial symmetry, such as in the distal centriole of human spermatozoon. Atypical centrioles may have evolved at least eight times independently during vertebrate evolution and may evolve in the sperm after internal fertilization evolves.

It wasn't clear why centriole become atypical until recently. The atypical distal centriole forms a dynamic basal complex (DBC) that, together with other structures in the sperm neck, facilitates a cascade of internal sliding, coupling tail beating with head kinking. The atypical distal centriole's properties suggest that it evolved into a transmission system that couples the sperm tail motors to the whole sperm, thereby enhancing sperm function.

title: Centriole


text:
Creation science

Creation science or scientific creationism is a pseudoscientific form of Young Earth creationism which claims to offer scientific arguments for certain literalist and inerrantist interpretations of the Bible. It is often presented without overt faith-based language, but instead relies on reinterpreting scientific results to argue that various myths in the Book of Genesis and other select biblical passages are scientifically valid. The most commonly advanced ideas of creation science include special creation based on the Genesis creation narrative and flood geology based on the Genesis flood narrative. Creationists also claim they can disprove or reexplain a variety of scientific facts, theories and paradigms of geology, cosmology, biological evolution, archaeology,  history, and linguistics using creation science. Creation science was foundational to intelligent design.

The overwhelming consensus of the scientific community is that creation science fails to qualify as scientific because it lacks empirical support, supplies no testable hypotheses, and resolves to describe natural history in terms of scientifically untestable supernatural causes. Courts, most often in the United States where the question has been asked in the context of teaching the subject in public schools, have consistently ruled since the 1980s that creation science is a religious view rather than a scientific one. Historians, philosophers of science and skeptics have described creation science as a pseudoscientific attempt to map the Bible into scientific facts. Professional biologists have criticized creation science for being unscholarly, and even as a dishonest and misguided sham, with extremely harmful educational consequences.

Religious basis
Creation science is based largely upon chapters 1–11 of the Book of Genesis. These describe how God calls the world into existence through the power of speech ("And God said, Let there be light," etc.) in six days, calls all the animals and plants into existence, and molds the first man from clay and the first woman from a rib taken from the man's side; a worldwide flood destroys all life except for Noah and his family and representatives of the animals, and Noah becomes the ancestor of the 70 "nations" of the world; the nations live together until the incident of the Tower of Babel, when God disperses them and gives them their different languages. Creation science attempts to explain history and science within the span of Biblical chronology, which places the initial act of creation some six thousand years ago.

Modern religious affiliations
Most creation science proponents hold fundamentalist or Evangelical Christian beliefs in Biblical literalism or Biblical inerrancy, as opposed to the higher criticism supported by liberal Christianity in the Fundamentalist–Modernist Controversy. However, there are also examples of Islamic and Jewish scientific creationism that conform to the accounts of creation as recorded in their religious doctrines.

The Seventh-day Adventist Church has a history of support for creation science. This dates back to George McCready Price, an active Seventh-day Adventist who developed views of flood geology, which formed the basis of creation science. This work was continued by the Geoscience Research Institute, an official institute of the Seventh-day Adventist Church, located on its Loma Linda University campus in California.

Creation science is generally rejected by the Church of England as well as the Roman Catholic Church. The Pontifical Gregorian University has officially discussed intelligent design as a "cultural phenomenon" without scientific elements. The Church of England's official website cites Charles Darwin's local work assisting people in his religious parish.

Views on science
Creation science rejects evolution and the common descent of all living things on Earth. Instead, it asserts that the field of evolutionary biology is itself pseudoscientific or even a religion. Creationists argue instead for a system called baraminology, which considers the living world to be descended from uniquely created kinds or "baramins."

Creation science incorporates the concept of catastrophism to reconcile current landforms and fossil distributions with Biblical interpretations, proposing the remains resulted from successive cataclysmic events, such as a worldwide flood and subsequent ice age. It rejects one of the fundamental principles of modern geology (and of modern science generally), uniformitarianism, which applies the same physical and geological laws observed on the Earth today to interpret the Earth's geological history.

Sometimes creationists attack other scientific concepts, like the Big Bang cosmological model or methods of scientific dating based upon radioactive decay. Young Earth creationists also reject current estimates of the age of the universe and the age of the Earth, arguing for creationist cosmologies with timescales much shorter than those determined by modern physical cosmology and geological science, typically less than 10,000 years.

The scientific community has overwhelmingly rejected the ideas put forth in creation science as lying outside the boundaries of a legitimate science. The foundational premises underlying scientific creationism disqualify it as a science because the answers to all inquiry therein are preordained to conform to Bible doctrine, and because that inquiry is constructed upon theories which are not empirically testable in nature.

Scientists also deem creation science's attacks against biological evolution to be without scientific merit. The views of the scientific community were accepted in two significant court decisions in the 1980s, which found the field of creation science to be a religious mode of inquiry, not a scientific one.

History
Creation science began in the 1960s, as a fundamentalist Christian effort in the United States to prove Biblical inerrancy and nullify the scientific evidence for evolution. It has since developed a sizable religious following in the United States, with creation science ministries branching worldwide. The main ideas in creation science are: the belief in creation ex nihilo (Latin: out of nothing); the conviction that the Earth was created within the last 6,000–10,000 years; the belief that humans and other life on Earth were created as distinct fixed "baraminological" kinds; and "flood geology" or the idea that fossils found in geological strata were deposited during a cataclysmic flood which completely covered the entire Earth. As a result, creationists also challenge the geologic and astrophysical measurements of the age of the Earth and the universe along with their origins, which creationists believe are irreconcilable with the account in the Book of Genesis. Creation science proponents often refer to the theory of evolution as "Darwinism" or as "Darwinian evolution."

The creation science texts and curricula that first emerged in the 1960s focused upon concepts derived from a literal interpretation of the Bible and were overtly religious in nature, most notably proposing Noah's flood in the Biblical Genesis account as an explanation for the geological and fossil record. These works attracted little notice beyond the schools and congregations of conservative fundamental and Evangelical Christians until the 1970s, when its followers challenged the teaching of evolution in the public schools and other venues in the United States, bringing it to the attention of the public-at-large and the scientific community. Many school boards and lawmakers were persuaded to include the teaching of creation science alongside evolution in the science curriculum. Creation science texts and curricula used in churches and Christian schools were revised to eliminate their Biblical and theological references, and less explicitly sectarian versions of creation science education were introduced in public schools in Louisiana, Arkansas, and other regions in the United States.

The 1982 ruling in McLean v. Arkansas found that creation science fails to meet the essential characteristics of science and that its chief intent is to advance a particular religious view. The teaching of creation science in public schools in the United States effectively ended in 1987 following the United States Supreme Court decision in Edwards v. Aguillard. The court affirmed that a statute requiring the teaching of creation science alongside evolution when evolution is taught in Louisiana public schools was unconstitutional because its sole true purpose was to advance a particular religious belief.

In response to this ruling, drafts of the creation science school textbook Of Pandas and People were edited to change references of creation to intelligent design before its publication in 1989. The intelligent design movement promoted this version. Requiring intelligent design to be taught in public school science classes was found to be unconstitutional in the 2005 Kitzmiller v. Dover Area School District federal court case.

Before 1960s
The teaching of evolution was gradually introduced into more and more public high school textbooks in the United States after 1900, but in the aftermath of the First World War the growth of fundamentalist Christianity gave rise to a creationist opposition to such teaching. Legislation prohibiting the teaching of evolution was passed in certain regions, most notably Tennessee's Butler Act of 1925.

The Soviet Union's successful launch of Sputnik 1 in 1957 sparked national concern that the science education in public schools was outdated. In 1958, the United States passed National Defense Education Act which introduced new education guidelines for science instruction. With federal grant funding, the Biological Sciences Curriculum Study (BSCS) drafted new standards for the public schools' science textbooks which included the teaching of evolution. Almost half the nation's high schools were using textbooks based on the guidelines of the BSCS soon after they were published in 1963.

The Tennessee legislature did not repeal the Butler Act until 1967.

Creation science (dubbed "scientific creationism" at the time) emerged as an organized movement during the 1960s. It was strongly influenced by the earlier work of armchair geologist George McCready Price who wrote works such as Illogical Geology: The Weakest Point in the Evolution Theory (1906) and The New Geology (1923) to advance what he termed "new catastrophism" and dispute the current geological time frames and explanations of geologic history. Price was cited at the Scopes Trial of 1925, but his writings had no credence among geologists and other scientists. Price's "new catastrophism" was also disputed by most other creationists until its revival with the 1961 publication of The Genesis Flood by John C. Whitcomb and Henry M. Morris, a work which quickly became an important text on the issue to fundamentalist Christians and expanded the field of creation science beyond critiques of geology into biology and cosmology as well. Soon after its publication, a movement was underway to have the subject taught in United States' public schools.

Court determinations
The various state laws prohibiting teaching of evolution were overturned in 1968 when the United States Supreme Court ruled in Epperson v. Arkansas such laws violated the Establishment Clause of the First Amendment to the United States Constitution. This ruling inspired a new creationist movement to promote laws requiring that schools give balanced treatment to creation science when evolution is taught. The 1981 Arkansas Act 590 was one such law that carefully detailed the principles of creation science that were to receive equal time in public schools alongside evolutionary principles. The act defined creation science as follows:

"'Creation-science' means the scientific evidences for creation and inferences from those evidences. Creation-science includes the scientific evidences and related inferences that indicate:
 * Sudden creation of the universe, and, in particular, life, from nothing;
 * The insufficiency of mutation and natural selection in bringing about development of all living kinds from a single organism;
 * Changes only with fixed limits of originally created kinds of plants and animals;
 * Separate ancestry for man and apes;
 * Explanation of the earth's geology by catastrophism, including the occurrence of worldwide flood; and
 * A relatively recent inception of the earth and living kinds."

This legislation was examined in McLean v. Arkansas, and the ruling handed down on January 5, 1982, concluded that creation-science as defined in the act "is simply not science". The judgement defined the following as essential characteristics of science:
 * It is guided by natural law;
 * It has to be explanatory by reference to nature law;
 * It is testable against the empirical world;
 * Its conclusions are tentative, i.e., are not necessarily the final word; and
 * It is falsifiable.

The court ruled that creation science failed to meet these essential characteristics and identified specific reasons. After examining the key concepts from creation science, the court found:
 * Sudden creation "from nothing" calls upon a supernatural intervention, not natural law, and is neither testable nor falsifiable
 * Objections in creation science that mutation and natural selection are insufficient to explain common origins was an incomplete negative generalization
 * 'Kinds' are not scientific classifications, and creation science's claims of an outer limit to the evolutionary change possible of species are not explained scientifically or by natural law
 * The separate ancestry of man and apes is an assertion rather than a scientific explanation, and did not derive from any scientific fact or theory
 * Catastrophism, including its identification of the worldwide flood, failed as a science
 * "Relatively recent inception" was the product of religious readings and had no scientific meaning, and was neither the product of, nor explainable by, natural law; nor is it tentative

The court further noted that no recognized scientific journal had published any article espousing the creation science theory as described in the Arkansas law, and stated that the testimony presented by defense attributing the absence to censorship was not credible.

In its ruling, the court wrote that for any theory to qualify as scientific, the theory must be tentative, and open to revision or abandonment as new facts come to light. It wrote that any methodology which begins with an immutable conclusion that cannot be revised or rejected, regardless of the evidence, is not a scientific theory. The court found that creation science does not culminate in conclusions formed from scientific inquiry, but instead begins with the conclusion, one taken from a literal wording of the Book of Genesis, and seeks only scientific evidence to support it.

The law in Arkansas adopted the same two-model approach as that put forward by the Institute for Creation Research, one allowing only two possible explanations for the origins of life and existence of man, plants and animals: it was either the work of a creator or it was not. Scientific evidence that failed to support the theory of evolution was posed as necessarily scientific evidence in support of creationism, but in its judgment the court ruled this approach to be no more than a "contrived dualism which has not scientific factual basis or legitimate educational purpose."

The judge concluded that "Act 590 is a religious crusade, coupled with a desire to conceal this fact," and that it violated the First Amendment's Establishment Clause. The decision was not appealed to a higher court, but had a powerful influence on subsequent rulings. Louisiana's 1982 Balanced Treatment for Creation-Science and Evolution-Science Act, authored by State Senator Bill P. Keith, judged in the 1987 United States Supreme Court case Edwards v. Aguillard, and was handed a similar ruling. It found the law to require the balanced teaching of creation science with evolution had a particular religious purpose and was therefore unconstitutional.

Intelligent design splits off
In 1984, The Mystery of Life's Origin was first published. It was co-authored by chemist and creationist Charles B. Thaxton with Walter L. Bradley and Roger L. Olsen, the foreword written by Dean H. Kenyon, and sponsored by the Christian-based Foundation for Thought and Ethics (FTE). The work presented scientific arguments against current theories of abiogenesis and offered a hypothesis of special creation instead. While the focus of creation science had until that time centered primarily on the criticism of the fossil evidence for evolution and validation of the creation myth of the Bible, this new work posed the question whether science reveals that even the simplest living systems were far too complex to have developed by natural, unguided processes.

Kenyon later co-wrote with creationist Percival Davis a book intended as a "scientific brief for creationism" to use as a supplement to public high school biology textbooks. Thaxton was enlisted as the book's editor, and the book received publishing support from the FTE. Prior to its release, the 1987 Supreme Court ruling in Edwards v. Aguillard barred the teaching of creation science and creationism in public school classrooms. The book, originally titled Biology and Creation but renamed Of Pandas and People, was released in 1989 and became the first published work to promote the anti-evolutionist design argument under the name intelligent design. The contents of the book later became a focus of evidence in the federal court case, Kitzmiller v. Dover Area School District, when a group of parents filed suit to halt the teaching of intelligent design in Dover, Pennsylvania, public schools. School board officials there had attempted to include Of Pandas and People in their biology classrooms and testimony given during the trial revealed the book was originally written as a creationist text but following the adverse decision in the Supreme Court it underwent simple cosmetic editing to remove the explicit allusions to "creation" or "creator," and replace them instead with references to "design" or "designer."

By the mid-1990s, intelligent design had become a separate movement. The creation science movement is distinguished from the intelligent design movement, or neo-creationism, because most advocates of creation science accept scripture as a literal and inerrant historical account, and their primary goal is to corroborate the scriptural account through the use of science. In contrast, as a matter of principle, neo-creationism eschews references to scripture altogether in its polemics and stated goals (see Wedge strategy). By so doing, intelligent design proponents have attempted to succeed where creation science has failed in securing a place in public school science curricula. Carefully avoiding any reference to the identity of the intelligent designer as God in their public arguments, intelligent design proponents sought to reintroduce the creationist ideas into science classrooms while sidestepping the First Amendment's prohibition against religious infringement. However, the intelligent design curriculum was struck down as a violation of the Establishment Clause in Kitzmiller v. Dover Area School District, the judge in the case ruled "that ID is nothing less than the progeny of creationism."

Today, creation science as an organized movement is primarily centered within the United States. Creation science organizations are also known in other countries, most notably Creation Ministries International which was founded (under the name Creation Science Foundation) in Australia. Proponents are usually aligned with a Christian denomination, primarily with those characterized as evangelical, conservative, or fundamentalist. While creationist movements also exist in Islam and Judaism, these movements do not use the phrase creation science to describe their beliefs.

Issues
Creation science has its roots in the work of young Earth creationist George McCready Price disputing modern science's account of natural history, focusing particularly on geology and its concept of uniformitarianism, and his efforts instead to furnish an alternative empirical explanation of observable phenomena which was compatible with strict Biblical literalism. Price's work was later discovered by civil engineer Henry M. Morris, who is now considered to be the father of creation science. Morris and later creationists expanded the scope with attacks against the broad spectrum scientific findings that point to the antiquity of the Universe and common ancestry among species, including growing body of evidence from the fossil record, absolute dating techniques, and cosmogony.

The proponents of creation science often say that they are concerned with religious and moral questions as well as natural observations and predictive hypotheses. Many state that their opposition to scientific evolution is primarily based on religion.

The overwhelming majority of scientists are in agreement that the claims of science are necessarily limited to those that develop from natural observations and experiments which can be replicated and substantiated by other scientists, and that claims made by creation science do not meet those criteria. Duane Gish, a prominent creation science proponent, has similarly claimed, "We do not know how the creator created, what processes He used, for He used processes which are not now operating anywhere in the natural universe. This is why we refer to creation as special creation. We cannot discover by scientific investigation anything about the creative processes used by the Creator." But he also makes the same claim against science's evolutionary theory, maintaining that on the subject of origins, scientific evolution is a religious theory which cannot be validated by science.

Metaphysical assumptions
Creation science makes the a priori metaphysical assumption that there exists a creator of the life whose origin is being examined. Christian creation science holds that the description of creation is given in the Bible, that the Bible is inerrant in this description (and elsewhere), and therefore empirical scientific evidence must correspond with that description. Creationists also view the preclusion of all supernatural explanations within the sciences as a doctrinaire commitment to exclude the supreme being and miracles. They claim this to be the motivating factor in science's acceptance of Darwinism, a term used in creation science to refer to evolutionary biology which is also often used as a disparagement. Critics argue that creation science is religious rather than scientific because it stems from faith in a religious text rather than by the application of the scientific method. The United States National Academy of Sciences (NAS) has stated unequivocally, "Evolution pervades all biological phenomena. To ignore that it occurred or to classify it as a form of dogma is to deprive the student of the most fundamental organizational concept in the biological sciences. No other biological concept has been more extensively tested and more thoroughly corroborated than the evolutionary history of organisms." Anthropologist Eugenie Scott has noted further, "Religious opposition to evolution propels antievolutionism. Although antievolutionists pay lip service to supposed scientific problems with evolution, what motivates them to battle its teaching is apprehension over the implications of evolution for religion."

Creation science advocates argue that scientific theories of the origins of the Universe, Earth, and life are rooted in a priori presumptions of methodological naturalism and uniformitarianism, each of which they reject. In some areas of science such as chemistry, meteorology or medicine, creation science proponents do not necessarily challenge the application of naturalistic or uniformitarian assumptions, but instead single out those scientific theories they judge to be in conflict with their religious beliefs, and it is against those theories that they concentrate their efforts.

Religious criticism
Many mainstream Christian churches criticize creation science on theological grounds, asserting either that religious faith alone should be a sufficient basis for belief in the truth of creation, or that efforts to prove the Genesis account of creation on scientific grounds are inherently futile because reason is subordinate to faith and cannot thus be used to prove it.

Many Christian theologies, including Liberal Christianity, consider the Genesis creation narrative to be a poetic and allegorical work rather than a literal history, and many Christian churches—including the Eastern Orthodox Church, the Roman Catholic, Anglican and the more liberal denominations of the Lutheran, Methodist, Congregationalist and Presbyterian faiths—have either rejected creation science outright or are ambivalent to it. Belief in non-literal interpretations of Genesis is often cited as going back to Saint Augustine.

Theistic evolution and evolutionary creationism are theologies that reconcile belief in a creator with biological evolution. Each holds the view that there is a creator but that this creator has employed the natural force of evolution to unfold a divine plan. Religious representatives from faiths compatible with theistic evolution and evolutionary creationism have challenged the growing perception that belief in a creator is inconsistent with the acceptance of evolutionary theory. Spokespersons from the Catholic Church have specifically criticized biblical creationism for relying upon literal interpretations of biblical scripture as the basis for determining scientific fact.

Scientific criticism
The National Academy of Sciences states that "the claims of creation science lack empirical support and cannot be meaningfully tested" and that "creation science is in fact not science and should not be presented as such in science classes." According to Joyce Arthur writing for Skeptic magazine, the "creation 'science' movement gains much of its strength through the use of distortion and scientifically unethical tactics" and "seriously misrepresents the theory of evolution."

Scientists have considered the hypotheses proposed by creation science and have rejected them because of a lack of evidence. Furthermore, the claims of creation science do not refer to natural causes and cannot be subject to meaningful tests, so they do not qualify as scientific hypotheses. In 1987, the United States Supreme Court ruled that creationism is religion, not science, and cannot be advocated in public school classrooms. Most mainline Christian denominations have concluded that the concept of evolution is not at odds with their descriptions of creation and human origins.

A summary of the objections to creation science by scientists follows:
 * Creation science is not falsifiable: An idea or hypothesis is generally not considered to be in the realm of science unless it can be potentially disproved with certain experiments, this is the concept of falsifiability in science. The act of creation as defined in creation science is not falsifiable because no testable bounds can be imposed on the creator. In creation science, the creator is defined as limitless, with the capacity to create (or not), through fiat alone, infinite universes, not just one, and endow each one with its own unique, unimaginable and incomparable character. It is impossible to disprove a claim when that claim as defined encompasses every conceivable contingency.
 * Creation science violates the principle of parsimony: Parsimony favours those explanations which rely on the fewest assumptions. Scientists prefer explanations that are consistent with known and supported facts and evidence and require the fewest assumptions to fill the remaining gaps. Many of the alternative claims made in creation science retreat from simpler scientific explanations and introduce more complications and conjecture into the equation.
 * Creation science is not, and cannot be, empirically or experimentally tested: Creationism posits supernatural causes which lie outside the realm of methodological naturalism and scientific experiment. Science can only test empirical, natural claims.
 * Creation science is not correctable, dynamic, tentative or progressive: Creation science adheres to a fixed and unchanging premise or "absolute truth," the "word of God," which is not open to change. Any evidence that runs contrary to that truth must be disregarded. In science, all claims are tentative, they are forever open to challenge, and must be discarded or adjusted when the weight of evidence demands it.

By invoking claims of "abrupt appearance" of species as a miraculous act, creation science is unsuited for the tools and methods demanded by science, and it cannot be considered scientific in the way that the term "science" is currently defined. Scientists and science writers commonly characterize creation science as a pseudoscience.

Historical, philosophical, and sociological criticism
Historically, the debate of whether creationism is compatible with science can be traced back to 1874, the year science historian John William Draper published his History of the Conflict between Religion and Science. In it Draper portrayed the entire history of scientific development as a war against religion. This presentation of history was propagated further by followers such as Andrew Dickson White in his two-volume A History of the Warfare of Science with Theology in Christendom (1896). Their conclusions have been disputed.

In the United States, the principal focus of creation science advocates is on the government-supported public school systems, which are prohibited by the Establishment Clause from promoting specific religions. Historical communities have argued that Biblical translations contain many translation errors and errata, and therefore that the use of biblical literalism in creation science is self-contradictory.

Biology
Creationist arguments in relation to biology center on an idea derived from Genesis that states that life was created by God, in a finite number of "created kinds," rather than through biological evolution from a common ancestor. Creationists contend that any observable speciation descends from these distinctly created kinds through inbreeding, deleterious mutations and other genetic mechanisms. Whereas evolutionary biologists and creationists share similar views of microevolution, creationists reject the fact that the process of macroevolution can explain common ancestry among organisms far beyond the level of common species. Creationists contend that there is no empirical evidence for new plant or animal species, and deny fossil evidence has ever been found documenting the process.

Popular arguments against evolution have changed since the publishing of Henry M. Morris' first book on the subject, Scientific Creationism (1974), but some consistent themes remain: that missing links or gaps in the fossil record are proof against evolution; that the increased complexity of organisms over time through evolution is not possible due to the law of increasing entropy; that it is impossible that the mechanism of natural selection could account for common ancestry; and that evolutionary theory is untestable. The origin of the human species is particularly hotly contested; the fossil remains of hominid ancestors are not considered by advocates of creation biology to be evidence for a speciation event involving Homo sapiens. Creationists also assert that early hominids, are either apes, or humans.

Richard Dawkins has explained evolution as "a theory of gradual, incremental change over millions of years, which starts with something very simple and works up along slow, gradual gradients to greater complexity," and described the existing fossil record as entirely consistent with that process. Biologists emphasize that transitional gaps between recovered fossils are to be expected, that the existence of any such gaps cannot be invoked to disprove evolution, and that instead the fossil evidence that could be used to disprove the theory would be those fossils which are found and which are entirely inconsistent with what can be predicted or anticipated by the evolutionary model. One example given by Dawkins was, "If there were a single hippo or rabbit in the Precambrian, that would completely blow evolution out of the water. None have ever been found."

Flood geology
Flood geology is a concept based on the belief that most of Earth's geological record was formed by the Great Flood described in the story of Noah's Ark. Fossils and fossil fuels are believed to have formed from animal and plant matter which was buried rapidly during this flood, while submarine canyons are explained as having formed during a rapid runoff from the continents at the end of the flood. Sedimentary strata are also claimed to have been predominantly laid down during or after Noah's flood and orogeny. Flood geology is a variant of catastrophism and is contrasted with geological science in that it rejects standard geological principles such as uniformitarianism and radiometric dating. For example, the Creation Research Society argues that "uniformitarianism is wishful thinking."

Geologists conclude that no evidence for such a flood is observed in the preserved rock layers and moreover that such a flood is physically impossible, given the current layout of land masses. For instance, since Mount Everest currently is approximately 8.8 kilometres in elevation and the Earth's surface area is 510,065,600 km2, the volume of water required to cover Mount Everest to a depth of 15 cubits (6.8 m), as indicated by Genesis 7:20, would be 4.6 billion cubic kilometres. Measurements of the amount of precipitable water vapor in the atmosphere have yielded results indicating that condensing all water vapor in a column of atmosphere would produce liquid water with a depth ranging between zero and approximately 70mm, depending on the date and the location of the column. Nevertheless, there continue to be adherents to the belief in flood geology, and in recent years new creationist models have been introduced such as catastrophic plate tectonics and catastrophic orogeny.

Radiometric dating
Creationists point to flawed experiments they have performed, which they claim demonstrate that 1.5 billion years of nuclear decay took place over a short period of time, from which they infer that "billion-fold speed-ups of nuclear decay" have occurred, a massive violation of the principle that radioisotope decay rates are constant, a core principle underlying nuclear physics generally, and radiometric dating in particular.

The scientific community points to numerous flaws in the creationists' experiments, to the fact that their results have not been accepted for publication by any peer-reviewed scientific journal, and to the fact that the creationist scientists conducting them were untrained in experimental geochronology. They have also been criticised for widely publicising the results of their research as successful despite their own admission of insurmountable problems with their hypothesis.

The constancy of the decay rates of isotopes is well supported in science. Evidence for this constancy includes the correspondences of date estimates taken from different radioactive isotopes as well as correspondences with non-radiometric dating techniques such as dendrochronology, ice core dating, and historical records. Although scientists have noted slight increases in the decay rate for isotopes subject to extreme pressures, those differences were too small to significantly impact date estimates. The constancy of the decay rates is also governed by first principles in quantum mechanics, wherein any deviation in the rate would require a change in the fundamental constants. According to these principles, a change in the fundamental constants could not influence different elements uniformly, and a comparison between each of the elements' resulting unique chronological timescales would then give inconsistent time estimates.

In refutation of young Earth claims of inconstant decay rates affecting the reliability of radiometric dating, Roger C. Wiens, a physicist specializing in isotope dating states: "There are only three quite technical instances where a half-life changes, and these do not affect the dating methods:"
 * 1) "Only one technical exception occurs under terrestrial conditions, and this is not for an isotope used for dating. ... The artificially-produced isotope, beryllium-7 has been shown to change by up to 1.5%, depending on its chemical environment. ... Heavier atoms are even less subject to these minute changes, so the dates of rocks made by electron-capture decays would only be off by at most a few hundredths of a percent."
 * 2) "... Another case is material inside of stars, which is in a plasma state where electrons are not bound to atoms. In the extremely hot stellar environment, a completely different kind of decay can occur. 'Bound-state beta decay' occurs when the nucleus emits an electron into a bound electronic state close to the nucleus. ... All normal matter, such as everything on Earth, the Moon, meteorites, etc. has electrons in normal positions, so these instances never apply to rocks, or anything colder than several hundred thousand degrees."
 * 3) "The last case also involves very fast-moving matter. It has been demonstrated by atomic clocks in very fast spacecraft. These atomic clocks slow down very slightly (only a second or so per year) as predicted by Einstein's theory of relativity. No rocks in our solar system are going fast enough to make a noticeable change in their dates."

Radiohaloes
In the 1970s, young Earth creationist Robert V. Gentry proposed that radiohaloes in certain granites represented evidence for the Earth being created instantaneously rather than gradually. This idea has been criticized by physicists and geologists on many grounds including that the rocks Gentry studied were not primordial and that the radionuclides in question need not have been in the rocks initially.

Thomas A. Baillieul, a geologist and retired senior environmental scientist with the United States Department of Energy, disputed Gentry's claims in an article entitled, "'Polonium Haloes' Refuted: A Review of 'Radioactive Halos in a Radio-Chronological and Cosmological Perspective' by Robert V. Gentry." Baillieul noted that Gentry was a physicist with no background in geology and given the absence of this background, Gentry had misrepresented the geological context from which the specimens were collected. Additionally, he noted that Gentry relied on research from the beginning of the 20th century, long before radioisotopes were thoroughly understood; that his assumption that a polonium isotope caused the rings was speculative; and that Gentry falsely argued that the half-life of radioactive elements varies with time. Gentry claimed that Baillieul could not publish his criticisms in a reputable scientific journal, although some of Baillieul's criticisms rested on work previously published in reputable scientific journals.

Creationist cosmologies
Several attempts have been made by creationists to construct a cosmology consistent with a young Universe rather than the standard cosmological age of the universe, based on the belief that Genesis describes the creation of the Universe as well as the Earth. The primary challenge for young-universe cosmologies is that the accepted distances in the Universe require millions or billions of years for light to travel to Earth (the "starlight problem"). An older creationist idea, proposed by creationist astronomer Barry Setterfield, is that the speed of light has decayed in the history of the Universe. More recently, creationist physicist Russell Humphreys has proposed a hypothesis called "white hole cosmology", asserting that the Universe expanded out of a white hole less than 10,000 years ago; claiming that the age of the universe is illusory and results from relativistic effects. Humphreys' cosmology is advocated by creationist organisations such as Answers in Genesis; however because its predictions conflict with current observations, it is not accepted by the scientific community.

Planetology
Various claims are made by creationists concerning alleged evidence that the age of the Solar System is of the order of thousands of years, in contrast to the scientifically accepted age of 4.6 billion years. It is commonly argued that the number of comets in the Solar System is much higher than would be expected given its supposed age. Young Earth Creationists reject the existence of the Kuiper belt and Oort cloud. They also argue that the recession of the Moon from the Earth is incompatible with either the Moon or the Earth being billions of years old. These claims have been refuted by planetologists.

In response to increasing evidence suggesting that Mars once possessed a wetter climate, some creationists have proposed that the global flood affected not only the Earth but also Mars and other planets. People who support this claim include creationist astronomer Wayne Spencer and Russell Humphreys.

An ongoing problem for creationists is the presence of impact craters on nearly all Solar System objects, which is consistent with scientific explanations of solar system origins but creates insuperable problems for young Earth claims. Creationists Harold Slusher and Richard Mandock, along with Glenn Morton (who later repudiated this claim ) asserted that impact craters on the Moon are subject to rock flow, and so cannot be more than a few thousand years old. While some creationist astronomers assert that different phases of meteoritic bombardment of the Solar System occurred during "creation week" and during the subsequent Great Flood, others regard this as unsupported by the evidence and call for further research.

Proponents

 * Answers in Genesis
 * Creation Ministries International
 * Creation Research Society
 * Geoscience Research Institute
 * Institute for Creation Research

Critics

 * American Museum of Natural History
 * National Science Teachers Association
 * National Center for Science Education
 * No Answers in Genesis
 * National Academy of Sciences
 * Scientific American
 * The BioLogos Foundation
 * The Skeptic's Dictionary
 * Talk.reason
 * TalkOrigins Archive

Critics

 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.
 * Statement adopted on April 24, 1982.

title: Creation science