What I've done has been to pull the images into a photo editor and play with color and contrast and posterizing until things become clearer. It's allowed me to read at least one age-at-death from a Findagrave image, which gave me a birthdate I don't have from anywhere else. (I use Gimp, but it's not the easiest to learn. However, it's opensource, so free.)
For military graves like these, though, I'd look for a plot map and index and records for the graveyard. Who administers it? Who mows it? Is there an office you could just walk into? Or records for this graveyard that you could access online?