Ah, you're right. The photograph should be colorblind friendly, but you need to know that the graffiti is there and take the picture in the first of course. I might try consulting people with colorblindness a bit more for future projects.
I did take the photo but glossed over it really fast. By that point I was pretty confident that the photos were all self-contained challenges for cash, but I was wrong. I can't read graffiti IRL either so I assumed it was just random squiggles.
