Whenever I export photos I add in a small watermark on the edge of the photo. I usually add in a white watermark which is slightly transparent. However, Some photos are entirely white in that edge, which means the watermark entirely disappears. In these situations, I would want to add in a dark watermark (same transparency level, but different color).
Is there any software that can achieve this automatically without my having to choose this manually? I envision the way it would work is by investigating the pixels underneath where the watermark goes, and then determining whether black or white text would fare better. I tried perusing imagemagick's options, but it seems like there is no such functionality. Lightroom also doesn't have this functionality.
I'd prefer macOS and a utility which is free. However, I'm open to other suggestions — at least I want to know if something like this even exists