Text has to be readable to be successful. You can achieve it by selecting a proper contrast, typography, text size etc. 

Check this image:

1984.design

Texts on images are easy to read. They do not blend with the images

One of the best techniques to have in your toolkit is designing with type on and around images. But it can also be one of the toughest concepts to pull off successfully. You have to have the right photo, a good eye for typography and know what you want to accomplish to make the most of adding type to an image.

17 Tips for Designing with Type on a Photo - Designmodo