A lot has been written about how to write meaningful alt attribute description for image elements, for those who use screen readers or with a slow connection where images that won't load. There are ground rules for when to use add a description to an alt attribute versus an empty alt text attribute. What I haven't been able to find anywhere is if it is useful to include colors in an alt attribute description. Even the W3 developer guidelines and WebAIM don't mention color in alt attribute descriptions at all. I've been looking at many websites' image alt text, from bloggers to corporations, and Twitter users who take advantage of their relatively new alt text feature. Many times I have seen an image described as something like "Person in a red shirt reading a blue book." or "A huge green field under a bright blue sky."
If anyone has any insight, I would love to learn more to write the best alt attribute descriptions.