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The formulas for computation of contrast are not influenced by non-normal eyesight considerations, it's only the acceptance thresholds that are affected. The c
by mark-r 7y ago
The formulas for computation of contrast are not influenced by non-normal eyesight considerations, it's only the acceptance thresholds that are affected. The computation of lightness in particular is based on weighting for average sensitivity to RGB. I've been dissatisfied with their formula for a long time, even though I have normal vision myself.
- zokier 7y agoThe comment from Andrew Somers[1] there is well worth a read. The salient quote here is > The method used for the WCAG 2.x contrast is, as I’ve discussed elsewhere, inconsistent with human perception models [1] https://uxmovement.com/buttons/the-myths-of-color-contrast-accessibility/#comment-92567 https://uxmovement.com/buttons/the-myths-of-color-contrast-a...
- mark-r 7y agoThanks for pointing that out, I missed it. It's refreshing to hear from someone who seems to know what they're talking about; I've looked at the WCAG document itself and haven't found a lot of justification for their recommendations.
- jacobolus 7y agoYou should think of it as a weak heuristic pointing in vaguely the right direction, rather than a careful scientifically validated metric. Similar in its technical sloppiness the “color rendering index” advertised on light bulbs.