background preloader

Visual impairment

Facebook Twitter

09. Type and colour. AUTHOR’S NOTE – You’re reading the HTML version of a chapter from the book Building Accessible Websites (ISBN 0-7357-1150-X).

09. Type and colour

Copyright © Joe Clark, 2002 (about the author). All rights reserved. ¶ Back to Contents Reading is the primary activity of the Web. For people with impaired vision who do not use screen readers, colour choices and, to a far lesser extent, type size become the accessibility issues. The big surprise is how little work you must do to provide for big type on your Websites (in fact, no work at all for the group that truly is visually-impaired). About Vischeck. What is it?

About Vischeck

Vischeck is a way of showing you what things look like to someone who is color blind. You can try Vischeck online- either run Vischeck on your own image files or run Vischeck on a web page. You can also download programs to let you run it on your own computer. Accessibility Color Wheel.

Check My Colours - Analyse the color contrast of your web pages. Color Contrast Comparison, by Joseph C Dolson. Color Oracle. Colour Contrast Visualiser. This tool allows you to visualise good colour combinations on a Photoshop style colour picker.

Colour Contrast Visualiser

It's primary use is finding acceptable colours from an existing inaccessible combination - while maintaining the aesthetic appeal of the original. Introduction While designing for the web, I use the WAT-C Contrast Analyser tool to ensure my text and background colours are readable to a wide range of people and devices. Occasionally I happen across a combination that to me appears to have sufficient contrast but is failed by the tool, to arrive at a good contrast that is passed, I have to adjust one or both of the colours and recheck until they pass. This is a tedious and time consuming task, and allot of skill is required to arrive at a combination that maintains the aesthetic of the original - the Colour Contrast Visualiser allows you to visualise the acceptable contrast ranges over a palette, so you can pick accessible colours with accuracy and confidence.

Development Information Download. Common Types and Characteristics of Visual Impairments. Common Eye Conditions Amblyopia: Amblyopia is also known as lazy eye.

Common Types and Characteristics of Visual Impairments

Children with a lazy eye may or may not be perceptible. Sometimes a lazy eye visibly turns in or out, but sometimes there is no outward sign. Amblyopia causes the eye to have reduced acuity due to the poor positioning of the eye and weak muscles. Color Theory for the Color-Blind. The web professional's online magazine of choice.

Color Theory for the Color-Blind

In: Articles By Mario Parisé Published on August 1, 2005 Being color-blind can be a real obstacle for anyone involved in design. For Web designers, this does not need to be true. You may think a subheader isn’t that important, but since most people scan Web pages, an inappropriately colored subheader means I won’t be able to read your carefully colored content. By understanding the science and logic behind color theory, I—and other color-blind designers—can intellectually know why colors go well together or don’t. For Internet Users with Visual Impairments. The internet enables users to access material and information on virtually any subject form anywhere there is an internet connection.

For Internet Users with Visual Impairments

For many users the internet offers a visual interface that can be used to find their way through the world wide web, but for those with visual impairments the visual cues do not server them as they do for seeing users. Consideration to those with visual impairments is imperative as the number of individuals with visual impairments increases. A visual impairment does not have to stand in the way of someone excelling in the Internet world or at web design schools. Content & Structure vs. Format & Images The main reason for a web page is information, or content; the first versiones of the internet could only be viewed in teletype mode. Information for designers to accommodate the visually impaired. How to Design Web Accessible Pages for the ColorBlind. International - Effective Color Contrast.

Home > Accessibility > Accessible Design > Accessible Print Design > Effective Color Contrast Designing for People with Partial Sight and Color Deficiencies by Aries Arditi, PhD This page contains three basic guidelines for making effective color choices that work for nearly everyone.

International - Effective Color Contrast

Following the guidelines are explanations of the three perceptual attributes of color -- hue, lightness and saturation -- as they are used by vision scientists. How does impaired vision affect color perception? Partial sight, aging and congenital color deficits all produce changes in perception that reduce the visual effectiveness of certain color combinations. 1. Dont assume that the lightness you perceive will be the same as the lightness perceived by people with color deficits. 2. For most people with partial sight and/or congenital color deficiencies, the lightness values of colors in the bottom half of the hue circle tend to be reduced. 3. Luminosity Colour Contrast Ratio Analyser. Colour Contrast The old Accessibility Evaluation and Repair Tools (AERT) suggested algorithm for determining colour contrast now directs here.

Luminosity Colour Contrast Ratio Analyser

The AERT algorithm was never a recommendation, and WCAG 2.0's luminosity contrast algorithm is recommended instead. Success Criterion 1.4.3 of WCAG 2.0 requires the visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following: Correction accessible - Red-Green Color Vision Impairment. An article I was reading in this week’s Economist magazine reminded me of Color Oracle, the software Bernhard Jenny (Swiss Institute of Cartography, ETH Zurich) developed to silence my continual prodding after listening to Cynthia Brewer talk about color blindness (color vision impairment) at a NACIS conference in 2000 (?!).

Red-Green Color Vision Impairment

It struck me there should be a tool that actually allowed the designer to see what their design looked like to someone with this impairment and not just try to make something work using limited “blessed” color combinations. An earlier effort produced Sim Daltonism, a Mac only tool that does a similar job as Color Oracle. Color Oracle takes the guesswork out of designing for color blindness by showing you in real time what people with common color vision impairments will see. Color Oracle applies a full screen color filter to art you are designing – independently of the software that you are using. Yes, if you try hard you can still figure it out. Sim Daltonism. Donate Download Sim Daltonism 1.1.2 → Mac App Store / Free Released on October 18, 2013.

Sim Daltonism

Note: Also available as a direct download (1.6 Mb) Description. Tools - Luminosity Contrast Ratio Analyser 1.1 - WAT-C [Web Accessibility Tools Consortium] This software has been superceded. Visually Impaired Users - How To Help Them - Accessible Web Design. Introduction A fairly large percent of Internet surfers are visually impaired. Whether members of this group are blind, colour blind or do not have the vision they once had, it's important their needs are recognised. The point of this article is to bring awareness to web designers about the importance of making web sites accessible, aiding visually impaired users and the HTML guidelines to creating a universal design solution.

Visually impaired users represent a large part of the Internet community who use online services such as online shopping, or online banking. Web applications and web sites should take into account visually impaired users as well as those with 20/20 vision. Identifying the audience - Issues to address. What is CVI? Why your child/students may have impaired vision: Ocular disorders: pathology of the eye(s) Neurological visual disorders: disturbed or reduced vision due to various brain abnormalities. The two types of visual disorders (ocular & neurological) can coexist.