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Contrast and grayscale

From: Jean-Marie D'Amour <jmdamour@videotron.ca>
Date: Tue, 18 Jun 2002 09:00:16 -0400
Message-Id: <>
To: w3c-wai-eo@w3.org


I have tested our recommandation about evaluating contrasts with grayscale 
in the context of a trainig.

I'm not satisfied about this because this kink of evaluation is very 

The checkpoint itself is rather subjective.

2.2 Ensure that foreground and background color combinations provide 
sufficient contrast when viewed by someone having color deficits or when 
viewed on a black and white screen.

What is a sufficient contrast? Advices differs and the grayscale test add 
nothing to this discussion. A relatively poor contrast that someone judged 
sufficient in full colours is also judged sufficient in grayscale.

A-Prompt has a dialog to objectively evaluate colour contrast, but this 
dialog appears only if the basic colours of the page (in the body element) 
are judged insufficient. Also, A-Prompt have choose to accept just clearly 
strong contrasts that limits a lot the range of possible colours.

I don't know how A-Prompt calculate colour contrast and I feel tha this 
evaluation is a little too severe.

Doe's someone know another objective test for colour contrast that can 
replace our subjective test with grayscale?



Jean-Marie D'Amour M.Éd.
CAMO pour personnes handicapées
Received on Tuesday, 18 June 2002 09:00:20 UTC

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