Ok, I think a clean and rebuild of the whole project did the trick. I always forget when I don't use it for sometimes. When something is doing weird with Qt you have to clean, qmake or rebuild to get everything in order. I will tag this issue as solved !

@raven-worx thank you for your reply ^^ helped me a lot :)

@Donn There's no way to loselessly convert 16 bit integers into 8 bit integers, so you can't use QImage to display your image without dropping some of the information. I advise to follow @SGaist's advice and research what OpenGL provides and if that will suit your needs. PS. Please don't post multiple times the same question! I see tree distinct instances of you asking the same thing over and over again in a few hours period. http://forum.qt.io/topic/64650/display-2d-array-of-type-uint16-as-grayscale-image http://forum.qt.io/topic/64657/display-uint16-image