Edit comment LC-1285 for Accessibility Guidelines Working Group

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Comment LC-1285: Comment Shortname:; Commenter: Andrew Arch <andrew.arch@visionaustralia.org> on behalf of Vision Australia; Message-id:; Section of the document concerned:

or; Refinement of the section concerned:; Status:
assigned to; Type:; Resolution status:
Response drafted Resolution implemented Reply sent to commenter; Response status:
No response from Commenter yet Commenter approved disposition Commenter objected to disposition
Commenter's response (URI):; Comment:
Comment: After playing with the luminosity algorithm for some time now, selected colour combinations are still almost unreadable - eg the algorithm allows blue-on-blue and orange-on-red, both combinations are very difficult to read by anyone. For an example see http://www.recsport.sa.gov.au/. IMHO, the colour-difference aspect of the old draft colour contrast algorithm needs to be reintroduced. For colours schemes that pass luminosity, but fail colour difference, see some of the combinations on http://juicystudio.com/services/coloursaferatio.php?background=003 and related pages.

Proposed Change:

add a colour difference aspect into the colour contrast SC; Related issues: (space separated ids); WG Notes: [TEAMA] Discussed in the 15 March 2007 telecon: resolution: accept as amended http://www.w3.org/WAI/GL/2007/03/15-wai-wcag-minutes.html @@ Ben to update contrast examples on trace site to id pages that include color deficiency examples @@ Michael to add resources on colour blindness to HOw to Meet doc; Resolution: While the contrast ratios used in the new algorithm do not include the calculations for color difference from the AERT algorithm, it requires a higher contrast ratio than would generally be required to address the needs of users with limited color perception. We have revised the contrast ratio somewhat to account for the conversion from nonlinear to linear RGB values and have provided examples of how various color combinations would be perceived with various color vision deficiencies in the Understanding documents.; (Please make sure the resolution is adapted for public consumption)