- From: Christophe Strobbe (on behalf of BenToWeb) <christophe.strobbe@esat.kuleuven.be>
- Date: Fri, 01 Feb 2008 21:09:22 +0100
- To: public-comments-wcag20@w3.org
Hi, Success criterion 1.4.3 relies on an algorithm for relative luminance [1] that is different from the algorithm in the draft for “Techniques For Accessibility Evaluation And Repair Tools” [2]. Research in BenToWeb investigated four different formulas for calculating colour contrast: * WAI Accessibility Evaluation and Repair Tools (Ridpath and Chisholm, 2000), brightness equations (“AERT/B”), * WAI Accessibility Evaluation and Repair Tools (Ridpath and Chisholm, 2000), colour contrast equations (“AERT/CC”), * W. S. Thune (2003) [3] has provided a series of equations, known as the Catman equations, using linear, quadratic and cubic functions (Catman1, Catman2, Catman3), * WCAG 2.0 – Working Draft 17 May 2007: contrast ratio definition (WCAG2). AERT/B turned out to be closer to real user experience (based on user testing) than the other algorithms. User testing led to the recommendation of a brightness difference of at least 66.8. [1] http://www.w3.org/TR/WCAG20/#contrast-ratiodef [2] http://www.w3.org/TR/AERT#color-contrast [3] http://www.iastate.edu/~class.12003.engl.313/cps/contrast.html Best regards, Christophe Strobbe -- Christophe Strobbe K.U.Leuven - Dept. of Electrical Engineering - SCD Research Group on Document Architectures Kasteelpark Arenberg 10 bus 2442 B-3001 Leuven-Heverlee BELGIUM tel: +32 16 32 85 51 http://www.docarch.be/ Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
Received on Friday, 1 February 2008 20:15:15 UTC