Follow-Up Comments on TC4R Symposium Nov. 19, 2012

Dear Shawn and Dave,

As a newcomer to W3C activity, I was very pleased to participate in the 
Monday symposium. Thanks to you for hosting an interesting event, and to 
Wayne for inviting my interest.

Here are a couple of follow-up thoughts for your consideration:

** Ranges of Low Vision

The participants emphasized the diversity of low-vision conditions and 
the importance of flexible customization. At a fairly coarse grain, it 
may be useful thinking about the following vision-based categories of users:
1)  Normal vision – The target audience for most web design.

2) Mild/moderate low vision – People for whom website customization may 
be adequate for good accessibility.

3) Moderate/severe low vision – People for whom added tools may be 
necessary, such as screen-magnification software (ZoomText, Magic, etc).

4) Blind/Severe Low Vision – People for whom all or most of web access 
must be accomplished nonvisually using screen readers, Braille displays, 
etc.

In designing standards, tools or recommendations, we should aim for 
graceful transition between these groups. Since we actually have a 
continuum of vision conditions, some people will need multiple resources 
e.g., customization tools and screen magnification. Or perhaps both 
screen magnification and screen reading capacity. At present, there can 
be conflicts between solutions targeted at the different levels. 
Universal design implies compatibility across solutions.

** Color and Contrast

Most people with low vision will benefit from maximizing luminance 
contrast, and many will also benefit from contrast reversal. As we 
discussed in the symposium, display settings that optimize these 
conditions are sometimes incompatible with web or other screen content. 
In my  own case, I have customized Windows color scheme using bright 
green letters on a black background for text. I use this default in my 
web browsers, and often find websites in which critical elements are 
invisible.

Color per se can be useful as a low-resolution cue in low vision. One 
issue, however, is that lots of people of acquired color defects 
associated with retinal or other forms of low vision. So it’s risky to 
assume that any given person with low vision will benefit from 
information coded by color.

Thanks.

--Gordon

Gordon E. Legge, Ph.D.
Department of Psychology
University of Minnesota

Received on Wednesday, 21 November 2012 13:12:35 UTC