Hello, all. I'm going to be blunt: a lot of folks aren't writing their image descriptions very efficiently. I hesitate to say they're written wrongly, but they aren't written as well as they could be.
That's alright, of course. Not everyone knows everything; in fact, I only know the things I do because I've had people tell me them over the years.
So, here are some notes about writing image descriptions...
If a flag has many stripes which are all shades of the same color, and they gradient, do not describe each stripe. From what I've been told, it can make the image in one's head muddle together. Instead, try describing a flag as forming a gradient from X to Y, or from X to Y and back to X, etcetera. This doesn't apply to flags with smaller amounts of stripes as far as I'm aware.
Do not use the term "offwhite" on its own. According to an anonymous asker years ago, there are many shades of offwhite, and just saying offwhite isn't very descriptive. Offwhite does not just refer to a yellowish white—it refers to anything that's close to white but not exact. So, specify the color further with terms such as "bluish offwhite," "near-white blue," or "bluish white."
Similarly, do not use terms such as "offblack." Specify the color further with terms such as "bluish black" or "near-black blue."
When describing symbols (mainly obscure ones), don't just say "an X symbol." For example, most people know what an infinity symbol is, but not many people will know what the mars symbol is. Just calling it "the mars symbol" isn't going to give an adequate picture.
Do not use hyperspecific colors. This is because not everyone will know what that color looks like. Terms such as "eggshell white," "plum," "amaranth," "royal blue," "chartreuse," and similarly hyperspecific names are too obscure. Use terms such as "pastel," "light," "dark," "desaturated," "blue-green," "bluish purple," and others instead.
There are also some things you should leave out. For example, most screenreaders will specify whether something is an image, so you needn't say something is an image. Otherwise, a screenreader might say "an image of an image of..." Likewise, most flags are rectangular, so you do not need to specify the shape unless it is something other than rectangular.
Keep your typing quirk out of flags if it involves anything that could possibly break screenreaders. This is likely well-known, but I will mention it anyway.