It wasn't a question of color quality, it was really a mechanical problem : pressing anywhere on the back panel would cause the colors to look as if the image had been "posterized" in photoshop.
This is the original image:
I looked for similar issues on the internet but found only one person who had this problem and he opted to sell the camera instead of repairing it, so I had to find my solution...
Not wanting (daring) to open up the camera myself, I filled out a service form on Canon's website and was (almost) ready to send the camera for repairs, except they indicated it would take about 20 days once they received the camera. (oh, and it would cost almost 300$)
No way I can wait a month without my camera !
So I found this post about how to disassemble the 5D and decided to give it a shot myself.
Funny thing : I found a loose screw laying around inside the body of the 5D... And I don't mean "loose" as in "not tight". I mean "loose" as in "free-as-a-bird" ! Luckily I also found where it belonged! (In the lower right corner of the next picture. In fact, all the screws holding that PCB on the right of the camera, were loose and begging to fall off!
After a lot of fidgeting, I identified one of these flat cables as the culprit for the LCD problems. There was no apparent damage to the cable but it stopped working well when it was compressed too much at its bending point. My solution was to add an officially-not-canon-replacement-part : a small piece of rolled up masking tape!! I used it to prevent a sharp bend at the point where the cable normally folds.
I'm very happy that my "fix" works well. It took a little under 3 hours (research included) and saved me 300$ !
Here are two other pics of the camera :
(oh ... And I did manage to put it back together ! No Problem !)
