How to fix Pictures and Videos problem

I have problem viewing images and videos clearly.

This seems to affect high quality images. They appear as if there is a kind of filter. But on a very low quality image, I can see the image clearly as normal. Videos are not clear also. It appears as if my system fell into water or there is a filter on it.

Now apart from the log on screen (since the background contains a large image), I can work with my system as normal. But when I use it for few hours, and switch between windows, the windows overlaps on the screen. Like the previous window joins with the current window I switched to thereby making it unusable at that point.

I contacted Apple and they did reset my graphic/video setting but that did not help. So they guess it might be a hardware problem.

PS: I’m guessing it fell down, but the guy that was with it before the issue started said it didn’t fall down.

Please, any Idea how I can go about this?