comments on WCAG 2,9 draft

To the working group that authored this draft:

In general, this draft is vastly improved from that of last year.  Nice work!

Issues:

The goal of specifying visual contrast in a way that is measurable in a meaningful way is not achievable without making some assumptions about the display hardware used by the end-user. What MIGHT be possible, is to make some conservative assumptions about the display hardware's capabilities, in terms of maximum luminance, gamma, and color gamut, and then create an algorithm that computes contrast and estimates perceivability (or better, readability) and have minimum values for these. 

I'm still not comfortable with the usage of the word "normative" to mean "required for conformance." It's jargon, and doesn't add value to the document. I had to look it up in the glossary, as I suspect many readers of the WCAG will.  What's wrong with "required"?  Then everything that's not required will be assumed to be informative. Or is it non-normative?  Or are non-normative and informative synonymous? See? I still don't get it!

In the "Who benefits from Guideline 1.4," strike the word "easily" from the sentence about users with low vision. Some readers with low vision don't read anything easily.

Guideline 2.3 about photosensitive epilepsy is greatly improved from last year's draft in that it is more specific.  I would like to see more of the rationale underlying the specific requirements, however, both in luminance, and spatial patterns, or at least some references that support these decisions. I hope there is some research that can be cited to support these specific values....

Thank you for inviting me to comment on this draft.

Aries Arditi, Ph.D.
Senior Fellow in Vision Science
Arlene R. Gordon Research Institute
Lighthouse International
111 East 59th Street
New York, NY 10022

Tel: +1 212 821 9500 (direct)
Fax: +1 212 751 9667
http://www.lighthouse.org/research_staff_arditi.htm

Received on Thursday, 9 September 2004 21:14:58 UTC