As far as I can tell "colorat" means "colorful" as well as "colored." Like when I come downstairs in my brightly colored, patterned (colorful) PJs, someone usually says "Cat de colorat!" Colorful is a much more commonly used term in English, and I think it should be accepted as a correct answer.
So there are several potential meanings in English (BrE) that might be worth stating (meanings, not translations).
1) The images have been coloured. A line drawing or a black and white image has had colour applied. 2) The images are in colour. So originally film and TV was black and white, then they were improved (TV in my lifetime) and are now in colour. 3) The images are colourful. The use of multiple colours is an important part of the attractiveness of the image.
As ever in DL Romanian course the English appears to have been written by someone who doesn't really understand English like a native speaker.
I don't myself know enough Romanian to know whether this sentence (the Romanian version) would be used there, or which possible meaning would correspond most closely.
GOOGLE TRANSLATE uses "The images are colorful" which is still marked wrong by DL. I have reported and hope this calls attention to the problem.