Well, the clock has turned and anti-reflective coating is now completely reliable, whether you choose the more expensive Crizal anti reflective coating, or the less expensive anti reflection coatings that are available. Yes, if you leave your anti glare glasses on the dashboard of your car in Florida, the anti-reflective coating could show signs of stress, but this falls in the category of abuse. No-glare coating does cost an additional $20 to $90 depending on the underlying lens, but there are significant benefits to anti-reflective coating. Whether it is right for you - if it is worth the extra cost - is your decision. Your no glare glasses will work fine without anti-reflective coating, but the relaxation to your eyes and improved vision are usually worth it.

This requirement applies to situations in which images of text were intended to be understood as text. Incidental text, such as in photographs that happen to include a street sign, are not included. Nor is text that for some reason is designed to be invisible to all viewers. Stylized text, such as in corporate logos, should be treated in terms of its function on the page, which may or may not warrant including the content in the text alternative. Corporate visual guidelines beyond logo and logotype are not included in the exception.

Text is only purely decorative if the words can be rearranged or substituted without changing their purpose.

Due to anti-aliasing, particularly thin or unusual fonts may be rendered by user agents with a much fainter color than the actual text color defined in the underlying CSS. This can lead to situations where text has a contrast ratio that nominally passes the Success Criterion, but has a much lower contrast in practice. In these cases, best practice would be for authors to choose a font with stronger/thicker lines, or to aim for a foreground/background color combination that exceeds the normative requirements of this Success Criterion.

Refer to related resources for a list of tools that utilize the contrast ratio to analyze the contrast of Web content.

Web browsers, media players, plug-ins, and other programs — including assistive technologies — that help in retrieving, rendering, and interacting with Web content.

A contrast ratio of 3:1 is the minimum level recommended by [[ISO-9241-3]] and [[ANSI-HFES-100-1988]] for standard text and vision. The 4.5:1 ratio is used in this provision to account for the loss in contrast that results from moderately low visual acuity, congenital or acquired color deficiencies, or the loss of contrast sensitivity that typically accompanies aging.

When there is more available light to your eye, you can see better and more clearly. The result is a clearer, sharper vision and reduced eyestrain, which would benefit everyone. However in some situations, the benefits are more noticeable:

Contrast in art

In this provision there is an exception that reads "that are part of a picture that contains significant other visual content,". This exception is intended to separate pictures that have text in them from images of text that are done to replace text in order to get a particular look.

- Without anti-reflective AR coating, reflections on the lenses will prevent people from seeing your eyes. Actors, newscasters, and businessmen prefer AR so that their audience and associates can clearly see their eyes.

The contrast ratio of 4.5:1 was chosen for level AA because it compensated for the loss in contrast sensitivity usually experienced by users with vision loss equivalent to approximately 20/40 vision. (20/40 calculates to approximately 4.5:1.) 20/40 is commonly reported as typical visual acuity of elders at roughly age 80. [[GITTINGS-FOZARD]]

When there is a border around the letter, the border can add contrast and would be used in calculating the contrast between the letter and its background. A narrow border around the letter would be used as the letter. A wide border around the letter that fills in the inner details of the letters acts as a halo and would be considered background.

- Fluorescent lighting, computer screens, cash registers etc. all cause an increase of reflections in the workplace. This increase in reflections causes eye straing, headaches, fatigue and a decrease in work productivity.

Because different image editing applications default to different pixel densities (e.g., 72ppi or 96ppi), specifying point sizes for fonts from within an image editing application can be unreliable when it comes to presenting text at a specific size. When creating images of large-scale text, authors should ensure that the text in the resulting image is roughly equivalent to 1.2 and 1.5 em or to 120% or 150% of the default size for body text. For example, for a 72ppi image, an author would need to use approximately 19pt and 24pt font sizes in order to successfully present images of large-scale text to a user.

Eyeglasses.com offers three basic types of coatings. On our least expensive lenses and within a restricted prescription range, anti-reflective AR coatings are an extra $20. This is possible because the lenses are coated in a mass production of tens of thousands of lenses. On other lenses that are custom made, we offer a $59 anti-reflective AR coating which is an excellent coating. However, it is not quite as good at the premium Crizal AR coatings offered by Essilor.

The 18 and 14 point sizes for roman texts are taken from the minimum size for large print (14pt) and the larger standard font size (18pt). For other fonts such as CJK languages, the "equivalent" sizes would be the minimum large print size used for those languages and the next larger standard large print size.

Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.

Determined from technology-specific data structures in a non-markup language and exposed to assistive technology via an accessibility API that is supported by commonly available assistive technology.

the relative brightness of any point in a colorspace, normalized to 0 for darkest black and 1 for lightest white

Contrast adjective

Because authors do not have control over user settings as to how text is rendered (for example font smoothing or anti-aliasing), the contrast ratio for text can be evaluated with anti-aliasing turned off.

Hues are perceived differently by users with color vision deficiencies (both congenital and acquired) resulting in different colors and relative luminance contrasts than for normally sighted users. Because of this, effective contrast and readability are different for this population. However, color deficiencies are so diverse that prescribing effective general use color pairs (for contrast) based on quantitative data is not feasible. Requiring good luminance contrast accommodates this by requiring contrast that is independent of color perception. Fortunately, most of the luminance contribution is from the mid and long wave receptors which largely overlap in their spectral responses. The result is that effective luminance contrast can generally be computed without regard to specific color deficiency, except for the use of predominantly long wavelength colors against darker colors (generally appearing black) for those who have protanopia. (We provide an advisory technique on avoiding red on black for that reason). For more information see [[ARDITI-KNOBLAUCH-1994]] [[ARDITI-KNOBLAUCH-1996]] [[ARDITI]].

Do you remember back in the 1990's when anti-glare coating regularly flaked, stained, and got psychedelic colors? It was a nightmare for opticians because customers got angry and would blame them for selling an expensive coating that did not perform well.

For the sRGB colorspace, the relative luminance of a color is defined as L = 0.2126 * R + 0.7152 * G + 0.0722 * B where R, G and B are defined as:

Images of text do not scale as well as text because they tend to pixelate. It is also harder to change foreground and background contrast and color combinations for images of text, which is necessary for some users. Therefore, we suggest using text wherever possible, and when not, consider supplying an image of higher resolution.

Before May 2021 the value of 0.04045 in the definition was different (0.03928). It was taken from an older version of the specification and has been updated. It has no practical effect on the calculations in the context of these guidelines.

Background color is the specified color of content over which the text is to be rendered in normal usage. It is a failure if no background color is specified when the text color is specified, because the user's default background color is unknown and cannot be evaluated for sufficient contrast. For the same reason, it is a failure if no text color is specified when a background color is specified.

This Success Criterion and its definitions use the terms "contrast ratio" and "relative luminance" rather than "luminance" to reflect the fact that Web content does not emit light itself. The contrast ratio gives a measure of the relative luminance that would result when displayed. (Because it is a ratio, it is dimensionless.)

Contrast meaning

When using text without specifying the font size, the smallest font size used on major browsers for unspecified text would be a reasonable size to assume for the font. If a level 1 heading is rendered in 14pt bold or higher on major browsers, then it would be reasonable to assume it is large text. Relative scaling can be calculated from the default sizes in a similar fashion.

The minimum contrast Success Criterion (1.4.3) applies to text in the page, including placeholder text and text that is shown when a pointer is hovering over an object or when an object has keyboard focus. If any of these are used in a page, the text needs to provide sufficient contrast.

Almost all systems used today to view Web content assume sRGB encoding. Unless it is known that another color space will be used to process and display the content, authors should evaluate using sRGB colorspace. If using other color spaces, see Understanding Success Criterion 1.4.3.

The contrast requirements for text also apply to images of text (text that has been rendered into pixels and then stored in an image format) - see Success Criterion 1.4.5: Images of Text.

User Interface Components that are not available for user interaction (e.g., a disabled control in HTML) are not required to meet contrast requirements. An inactive user interface component is visible but not currently operable. An example would be a submit button at the bottom of a form that is visible but cannot be activated until all the required fields in the form are completed.

hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents

sequence of characters that can be programmatically determined, where the sequence is expressing something in human language

Text that is decorative and conveys no information is excluded. For example, if random words are used to create a background and the words could be rearranged or substituted without changing meaning, then it would be decorative and would not need to meet this criterion.

The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving Web content from program objects or parsing markup into identifiable bundles.

- External reflections are a major problem when it comes to driving safely at night. The reflections from oncoming headlights, streetlamps, and the road can cause distractions and discomfort to the driver. Internal reflections can cause ghost images and result in a decrease in reaction time.

In contrast synonym

When evaluating this Success Criterion, the font size in points should be obtained from the user agent or calculated on font metrics in the way that user agents do. Point sizes are based on the CSS pt size as defined in CSS3 Values. The ratio between sizes in points and CSS pixels is 1pt = 1.333px, therefore 14pt and 18pt are equivalent to approximately 18.5px and 24px.

a language using combinations of movements of the hands and arms, facial expressions, or body positions to convey meaning

Anti-reflective coating is also called anti-glare glasses, no-glare coating, and anti-reflective glasses, and it refers to a series of layers that is adhered to the back and front surface of prescription lenses, or just the back of the lens if the lens is polarized. The purpose of anti-glare glasses is to help reduce the amount of reflections on the lens. Consisting of metal oxides, each layer is a thin film that is designed to block a specific wavelength of light. The more layers of film, the more wavelengths that are blocked. AR coating causes the light that reflects from the inner and outer surfaces of each film layer to become equal, thereby canceling each other out.

determined by software from author-supplied data provided in a way that different user agents, including assistive technologies, can extract and present this information to users in different modalities

Contrast in English

Some people with cognitive disabilities require color combinations or hues that have low contrast, and therefore we allow and encourage authors to provide mechanisms to adjust the foreground and background colors of the content. Some of the combinations that could be chosen may have contrast levels that will be lower than those those specified here. This is not a violation of this Success Criterion, provided there is a mechanism that will return to the required values set out here.

Because authors do not have control over user settings for font smoothing/anti-aliasing, when evaluating this Success Criterion, refer to the foreground and background colors obtained from the user agent, or the underlying markup and stylesheets, rather than the text as presented on screen.

WCAG conformance should be evaluated for color pairs specified in the content that an author would expect to appear adjacent in typical presentation. Authors need not consider unusual presentations, such as color changes made by the user agent, except where caused by authors' code.

Although this Success Criterion only applies to text, similar issues occur for content presented in charts, graphs, diagrams, and other non-text-based information, which is covered by Success Criterion 1.4.11 Non-Text Contrast.

Select the situation below that matches your content. Each situation includes techniques or combinations of techniques that are known and documented to be sufficient for that situation.

The following are common mistakes that are considered failures of this Success Criterion by the WCAG Working Group.

- Anti-reflective AR coating on the back side of sunglass lenses eliminate some problems. First is the annoying image of the eye that is reflected in the center of the lens and can be very distracting. Second is the glare hazard that is caused by the mirror effect of a dark lens. With sunglass lenses, light from behind the wearer can be reflected directly into the eye from the back of the lens surface, causing discomfort.

Contrast examples

Crizal is the best known anti-reflective coating on the market, and also the best and the most expensive. Before you choose Crizal, think carefully about whether you even need or want anti-reflective coating on your glasses. Anti-reflective AR coating is chosen by 28.5% of eyewear shoppers in the United States, compared to 50-90% in Europe. There are many reasons that could contribute to this gap, but the primary reason is probably the bad history that anti-reflective AR coating had in its early years. In the 80's and 90's, anti-reflective AR coatings had a single layer which would craze, scratch or smudge easily. Today's AR coatings includes a harder layer of scratch resistant coating, in addition to oleophobic (anti-oil), hydrophobic (anti-liquid), and anti-static layers. These extra layers help to repel the things that lead to smudging and scratching. They also help to make the lenses easier to clean and thereby reduce surface scratches from excessive cleaning.

Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.

The rationale is based on a) adoption of the 3:1 contrast ratio for minimum acceptable contrast for normal observers, in the ANSI standard, and b) the empirical finding that in the population, visual acuity of 20/40 is associated with a contrast sensitivity loss of roughly 1.5 [[ARDITI-FAYE]]. A user with 20/40 would thus require a contrast ratio of 3 * 1.5 = 4.5 to 1. Following analogous empirical findings and the same logic, the user with 20/80 visual acuity would require contrast of about 7:1.

User interface components include form elements and links as well as components generated by scripts.

Contrast meaning in Hindi

Anti-reflective coating allows 8% more light to enter the eye. That 8% of light was bouncing off the outside of the lens, causing other people to see a shiny spot on your glasses and preventing them from seeing your eyes. Also, when a light source is overhead or behind you (as is often the case), light reflects off the inside of your lens and bounces into your eye, increasing eye fatigue.

Fonts with extraordinarily thin strokes or unusual features and characteristics that reduce the familiarity of their letter forms are harder to read, especially at lower contrast levels.

Text that is larger and has wider character strokes is easier to read at lower contrast. The contrast requirement for larger text is therefore lower. This allows authors to use a wider range of color choices for large text, which is helpful for design of pages, particularly titles. 18 point text or 14 point bold text is judged to be large enough to require a lower contrast ratio. (See The American Printing House for the Blind Guidelines for Large Printing and The Library of Congress Guidelines for Large Print under Resources). "18 point" and "bold" can both have different meanings in different fonts but, except for very thin or unusual fonts, they should be sufficient. Since there are so many different fonts, the general measures are used and a note regarding thin or unusual fonts is included in the definition for large-scale text.

Developed by Accessibility Guidelines Working Group (AG WG) Participants (Co-Chairs: Alastair Campbell, Charles Adams, Rachael Bradley Montgomery. W3C Staff Contact: Michael Cooper).

Strategies, standards, and supporting resources to make the Web accessible to people with disabilities.

Determined in a markup language from elements and attributes that are accessed directly by commonly available assistive technology.

The 3:1 and 4.5:1 contrast ratios referenced in this Success Criterion are intended to be treated as threshold values. When comparing the computed contrast ratio to the Success Criterion ratio, the computed values should not be rounded (e.g., 4.499:1 would not meet the 4.5:1 threshold).

with at least 18 point or 14 point bold or font size that would yield equivalent size for Chinese, Japanese and Korean (CJK) fonts

An applet has a "control" that can be used to move through content by line or page or random access. Since each of these would need to have a name and be settable independently, they would each be a "user interface component."

language that is spoken, written or signed (through visual or tactile means) to communicate with humans

text that has been rendered in a non-text form (e.g., an image) in order to achieve a particular visual effect

The contrast ratio of 7:1 was chosen for level AAA because it compensated for the loss in contrast sensitivity usually experienced by users with vision loss equivalent to approximately 20/80 vision. People with more than this degree of vision loss usually use assistive technologies to access their content (and the assistive technologies usually have contrast enhancing, as well as magnification capability built into them). The 7:1 level therefore generally provides compensation for the loss in contrast sensitivity experienced by users with low vision who do not use assistive technology and provides contrast enhancement for color deficiency as well.

The intent of this Success Criterion is to provide enough contrast between text and its background so that it can be read by people with moderately low vision (who do not use contrast-enhancing assistive technology). For people without color deficiencies, hue and saturation have minimal or no effect on legibility as assessed by reading performance (Knoblauch et al., 1991). Color deficiencies can affect luminance contrast somewhat. Therefore, in the recommendation, the contrast is calculated in such a way that color is not a key factor so that people who have a color vision deficit will also have adequate contrast between the text and the background.

Assistive technologies that are important in the context of this document include the following:

The ANSI/HFS 100-1988 standard calls for the contribution from ambient light to be included in the calculation of L1 and L2. The .05 value used is based on Typical Viewing Flare from [[IEC-4WD]].

Contrast meaning example

Author of this article:  Mark Agnew CEO of Eyeglasses.com, which he founded in 1999.  For over twenty years, he has educated consumers, improved their vision choices, and reduced costs in eyewear.  Mark authored The Eyeglasses Buying Guide, the most comprehensive and best-selling glasses buying guide in the world. Bio     LinkedIn     Blog     Facebook

Please share your ideas, suggestions, or comments via e-mail to the publicly-archived list group-ag-chairs@w3.org or via GitHub

functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).

Anti-reflective AR coatings always work better when they are made by the same maker as the lens itself. For example, Zeiss anti-reflective coating works best on Zeiss lenses, Pentax anti-reflective coating works best on Pentax lenses, and Crizal no glare coatings work best on Essilor and Varilux lenses. The reason for this is that the manufacturers each have their own formula for the underlying lens. That formula bonds best to an anti-reflective AR coating that is of the same chemical family. Premium anti-reflective coatings are actually bonded to the lens surface, becoming one with the lens.

For the purpose of Success Criteria 1.4.3 and 1.4.6, contrast is measured with respect to the specified background over which the text is rendered in normal usage. If no background color is specified, then white is assumed.

Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.

Tools are available that automatically do the calculations when testing contrast and flash.

The actual size of the character that a user sees is dependent both on the author-defined size and the user's display or user agent settings. For many mainstream body text fonts, 14 and 18 point is roughly equivalent to 1.2 and 1.5 em or to 120% or 150% of the default size for body text (assuming that the body font is 100%), but authors would need to check this for the particular fonts in use. When fonts are defined in relative units, the actual point size is calculated by the user agent for display. The point size should be obtained from the user agent, or calculated based on font metrics as the user agent does, when evaluating this success criterion. Users who have low vision would be responsible for choosing appropriate settings.

Calculations in [[ISO-9241-3]] and [[ANSI-HFES-100-1988]] are for body text. A relaxed contrast ratio is provided for text that is much larger.

If dithering occurs after delivery, then the source color value is used. For colors that are dithered at the source, the average values of the colors that are dithered should be used (average R, average G, and average B).

Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.

The content was developed as part of the WAI-Core projects funded by U.S. Federal funds. The user interface was designed by the Education and Outreach Working Group (EOWG) with contributions from Shadi Abou-Zahra, Steve Lee, and Shawn Lawton Henry as part of the WAI-Guide project, co-funded by the European Commission.

Font size is the size when the content is delivered. It does not include resizing that may be done by a user.

Multiple user interface components may be implemented as a single programmatic element. "Components" here is not tied to programming techniques, but rather to what the user perceives as separate controls.

What is meant by "component" or "user interface component" here is also sometimes called "user interface element".