Thread Subject: Re: Revised 2.1.A
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From: Gregg Vanderheiden
Date: Fri, Oct 19 2007 12:20 AM
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I think we need to define 'contrast ratio' here so it doesn't inherit
the definition from software content since this is real luminance. Do we
want to use the same formulae we have been talking about for labels?
(e.g. use "luminance contrast" and use (L1-L2)/L2 with minimum
Or do you want to use the contrast ratio (L1 + 0.05) / (L2 + 0.05)
Gregg C Vanderheiden Ph.D.
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Subject: [teitac-hardware] Revised 2.1.A
Revised proposed language for Luminance Contrast Ratio for Display.
Discussion indicated some confusion with this requirement which involves
direct light measurement and the Contrast Ratio used in SW/Web that is a
calculation based on RGB values.
Discussion or comments?
2.1-A - Luminance Contrast Ratio for Display
For displays on products, at least one mode must exist where the contrast
ratio between the luminance at light state compared to luminance at dark
state shall be at least 5:1.
Note: Light (or high) state typically refers to the lighter condition for
the display. For example, white content/background on an LCD. Dark (or low)
state typically refers to the darker condition for the display.
For example, black content/background on an LCD.
Rob Nerhood | Experience Design Group | Ergonomics Engineer
Dell, Inc. | One Dell Way | Round Rock, Texas 78682 - 7000
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