Re: A color tutorial from Tom Jewett

Hi Dick

Here is some information that might be helpful. 

This topic seems to come up again every few years.  

Before diving into it again — it might be helpful to know all the work and research that went into developing the measure in the first place.  It takes into account much more than most measures of contrast do - - including both low vision and the different types of color blindness. 

The current contrast measure was developed based on both international standards and research on low-vision and color blindness - and was done in collaboration with research scientist at the Lighthouse for the blind.  Over a year was spent on researching and developing it.   It was based on international standards and then adjusted to control for legibility and contrast when the different types of color blindness and low vision were applied.     We did this work because we were unable to find any other researchers who had done any work to account for these when coming up with their contrast measures. 

The current measure takes into account the following things  
Reseach on standard contrasts levels
Research quantifying the need for increased contrast with reduced visual acuity 
The quantification of the differences in contrast perceived with different color combinations for people with different types of color vision differences (including Protan, Deutan, Tritan, and Mono or Achro (no color) vision differences.
The range of contrast that would allow three items to maintain color contrast with each other.  (That is -   A contrasts sufficiently with B which contrasts sufficiently with C  without A and C having to be pure black and white. 
And the full range of colors that would be possible and still meet any color contrast requirements.   (In WCAG’s case   4.5:1 and 7:1) 

Any new efforts to revisit should be at least as thorough and take all of these into account quantitatively.   
By the way —If anyone is aware of such - please do let me know so I can capture that other information on the DeveloperSpace <http://ds.gpii.net/>  - a  central reference being developed to support developers, policy etc.    
(the MasterList <https://ds.gpii.net/learn/accessibility-masterlist> may also be of interest — with a full page devoted to applications, tools and research for each of the 80+ access strategies identified  - with a $50 reward for any strategy not listed or covered by a listed strategy ) 


As to the age of the tool — we are using tools that are hundreds of years old in science all the time. 
 The age is not really relevant. 

Is there something else that makes you think the old tool is no longer valid?

If so — that is where we should start.  With what the perceived problem is with the old tool. 
What has changed that made it no longer work? 

All the best. 

Gregg



> On May 23, 2019, at 2:53 PM, Wayne Dick <wayneedick@gmail.com> wrote:
> 
> I think it is time to look at contrast and color.
> Our formula may be the one, but it may not. This would really be a research effort. 
> As mentioned before, we can calibrate any new test on the same scale we use now so that the user interface of tests won't need to change much. 
> What we need muster is our talent in the mathematics, physics, electrical engineering, vision science, photography and art. 
> 
> There has been enough concern expressed about the current formula that it seems reasonable to review our research and improve it if needed. 
> 
> Maybe we need a different formula. Maybe we need to do more with accessibility testing to ensure standardized evaluation. I just don't know, but I am concerned with the distrust of our numbers. 
> 
> I could use some suggestions about how to proceed organizationally. This is not controversial. We are using a 10 year old tool in rapidly evolving technology. A calm scientific review is in order. Tom Jewett and I are happy to contribute.
> 
> Best to All, Wayne
> 
> Best, Wayne
> 
>