My first book (Handbook of Natural Colorants. Bechtold, Thomas, Mussak, Rita) has a little information. (I have to admit to not reading the whole book, not even the blurb - I couldn't find it. I'll have to get used to this new format.) I found one mention of olives, in the Carotenoid Dyes - Production chapter. On page 237, olives are mentioned as being part of this group, along with kale, cabbage, carrots, etc. But then it goes on to say
In fruits where the color at the ripe stage is due to pigments other than carotenoids, e.g. anthocyanins such as yellow cherry, red currant strawberry and olive fruits, the carotenoid content decreases during ripening.So now I am confused; even though they must contain carotenoids, it seems that pigments are what colours olives and, presumably, the fabric. I am not sure what the pigments are or how stable they are.
I will have to keep looking. It is all getting a bit too scientific though.
The photo is not great, it is winter and gets dark before I think to take the pictures, so it is with flash again.