Seeking color minimums for low vision users

[zvi]

I converted rb's Easyread style to a layout layer. (You can see it live at http://zvi.dreamwidth.org/?s2id=86436 You can apply it to your own journal via Advanced Customization. The layout layer is #73107. The green theme is #73183.)

I'm trying to figure out what colors to use to make 3-4 high contrast color themes. My specific questions are

Foreground/background : what are the minimum brightness and color difference levels to use for low vision users? I've seen brightness 125, color difference 500. I've also seen (I think in an alternative measurement to color difference) that the contrast ratio should be either 4.5:1 or 7:1.

Adjacent text (i.e. plain text next to links) : what color difference minimum? Is there a brightness minimum? Is there a contrast ratio minimum?

I am planning to check my color contrasts with this Colour Contrast Check tool. If you know of a better one, let me know.

Also, I know there's red/green colorblindness and blue/green colorblindness ... any other color combos to avoid?

Comments

[yvi]

Also, I know there's red/green colorblindness and blue/green colorblindness ... any other color combos to avoid?

Sorry I can't help with the rest, but there's blue-yellow (much less common than red-green, which makes up about 99% of colorblindness but more common than blue-green, as far as I remember).

And maybe this: http://www.etre.com/tools/colourblindsimulator/ can help with that part.

[jeshyr]

I don't know the specific minimums, I suggest you follow whatever W3C suggests on that count.

For reference though:
black on white
white on black
and bright yellow (FFFF00) on black

seem to be the three most common very high contrast schemes used by low vision users. I'd suggest using white for links on the yellow text scheme and yellow for links on the white text scheme and 00f blue on the black text scheme.

Do you want me to come up with other "pretty" colour schemes also? I had planned to, but if you have it covered then I won't worry :)

Cheers
r

[ex_peasant441]

Visicheck mimics various types of colour-blindness.