As we all know, I am a big fan of well done ornamentation coloration. Something with a sail with no color to it tends to make me a little sad. Evolution and the artist both have a huge canvas in a good sized ornament on a dinosaur's body whether it's a neck frill, a Stegosaur plate, or a sail like the one Ouranosaurus bears. Of course, the artistic representation of a body ornament with no camouflage is perfectly feasible, a solid color, I mean. Though I find animals that have giant appendages that are a simple solid color less fascinating than those with camouflage and eye spots and the like. However, in images like this one those solid colors can also be camouflage on their own or, perhaps, sometimes the dinosaur was just too big to require camouflage. The predators in Africa at the time of the roaming about of Ouranosaurus were big enough to take this animal down however, so I do not believe that is the case here. Though Csotonyi's Ouranosaurus certainly has the ability to blend in with the drab surroundings it has with its simple single color hide.
Craig Brown's Ouranosaurus has gone with the just as popular tiger stripe camouflage. Also, with the background showing in his illustration, this color scheme would be acceptable camouflage. Though, of course, a little green wouldn't hurt in this exact setting, the assumption I make here is that the stripes are more well adapted to life between the oases. Desert camouflage is not, after all, very showy and assuming that this dinosaur lived mostly in a desert environment while trekking back and forth between the oases of the desert means that the camouflage that would have adapted would make much more sense if it had a very desert theme to it overall as it does here. Additionally, Brown's illustration of the animals looks a little more reptile in the face than some other illustrations of hadrosaurs that I have seen. That is not in any way a negative thing, but it is interesting to note.
I saved Walter Meyers' Ouranosaurus for last for a very good reason. First of all, Meyers' Ouranosaurs have some interesting marking going on. One, possibly marked as a male by more traits which I will get to in a second, has ruddy orange brown striping on a green body background. The other two animals have darker gray striping on their background body color of green. Additionally, the male has a large grouping of osteoderms or perhaps large skin protrusions along the upper ridge of his nasal and and orbital bones on his skull. This and the fact that he is clearly a slightly larger built animal lead me to assume he is being portrayed as male. Female reptiles, and some believe dinosaurs as well, are typically larger than the males, so why assume that the largest is male and not female? The reason is that typically a pack or herd oriented under a male animal with females around the central "bull" is common but herd mentality under matriarchal leadership is typically devoid of males who are included in the group only during mating season once past the age of maturity, in all the examples I can come up with at any rate. Please share if you can think of examples that disprove this!