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Re: Suggested edits for guidelines 1.4 CONTRAST

From: Makoto UEKI - Infoaxia, Inc. - <ueki@infoaxia.co.jp>
Date: Fri, 24 Feb 2006 23:36:22 +0900
To: w3c-wai-gl@w3.org
Message-Id: <20060224232217.2857.UEKI@infoaxia.co.jp>

Hello Gregg,

This is easier to understand and to be tranlated than the old definition.
It was hard for me to understand this definition when I tried to
translate it into Japanese.

<blockquote>
> luminosity contrast ratio 
> {{(L1 + 0.05) / (L2 + 0.05), where L1 is the luminosity of the lighter of
> the text and background colors, and L2 is the luminosity of the darker of
> the text and background colors.
</blockquote>

I think we'd better say:
- lighter of the text "or" background colors
- darker of the text "or" background colors

If we say "and", they look like "both the text and background colors" to
me and it is confusing a bit. In the old definition, it said "the higher
value (of text or background)". I just want to clarify what we mean by
this definition. 


Cheers,
Makoto


On Wed, 22 Feb 2006 01:38:23 -0600
"Gregg Vanderheiden" <gv@trace.wisc.edu> wrote:

> 
> 
> Here are some suggested edits for the WCAG Contrast guideline Definitions  
> 
> They are to clarify some ambiguous parts but do not change the guidelines.
> 
> 
> Gregg
> 
>  -- ------------------------------ 
> Gregg C Vanderheiden Ph.D. 
> Professor - Ind. Engr. & BioMed Engr.
> Director - Trace R & D Center 
> University of Wisconsin-Madison 
> The Player for my DSS sound file is at http://tinyurl.com/dho6b 
> 
> 
> Note:  All modified content segments are enclosed in double braces {{}}
> 
> 
> definition for "luminosity contrast ratio"
> 
> 
> [old definition...]
> 
> luminosity contrast ratio 
> {{(L1+.05) / (L2+.05) where L is luminosity and is defined as .2126*R +
> .7152*G + .0722B using linearized R, G, and B values. Linearized R (for
> example) = (R/FS)^2.2 where FS is full scale value (255 for 8 bit color
> channels). L1 is the higher value (of text or background) and L2 is the
> lower value.}}
> 
> [end of old definition]
> 
> 
> [new definition...]
> 
> luminosity contrast ratio 
> {{(L1 + 0.05) / (L2 + 0.05), where L1 is the luminosity of the lighter of
> the text and background colors, and L2 is the luminosity of the darker of
> the text and background colors.
> 
> The luminosity of a color is defined as 0.2126 * ((R / FS) ^ 2.2) + 0.7152 *
> ((G / FS) ^ 2.2) + 0.0722 * ((B / FS) ^ 2.2). R, G, and B are the red,
> green, and blue RGB values of the color; FS is the maximum possible full
> scale RGB value for R, G, and B (255 for eight bit color channels); and the
> "^" character is the exponentiation operator.
> 
> Note: Luminosity values can range from 0 (black) to 1 (white), and
> luminosity contrast ratios can range from 1 to 21.}}
> 
> [end of new definition]
> 
> 
> 
> 
> 

<以下、署名>
-- 
株式会社インフォアクシア 
植木 真 <ueki@infoaxia.co.jp>

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Received on Friday, 24 February 2006 14:43:08 GMT

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