I've contributed some changes and new covers for a profile (the Sorcerer's Apprentice (EAN #8717418289836))

The changes are accepted, but the covers are declined. There was only one vote. This was a yes vote from the user who has contributed the existing covers. So I assume he also thinks the new covers are better because the contribution was supported by the the user who contributed the existing covers.

I've noticed the changes in the contribution notes. I've added better cropped covers which were a bit wider than the existing covers. In my opinion the quality was also a bit better. The colors were more natural and the covers were a little bit sharper. The covers were taken from the original cover from a DVD with the correct EAN and the DVD was bought on the day the DVD was released.

Normally I can accept a declined contribution when there's a legit reason for it. IMHO there's no legit reason to decline them, so I was wondering if it's possible to get or ask for some more info when a contribution was declined. At the moment it is completely unclear why the images are rejected and I would still like to know what I've done wrong.

I don't know if the screeners reacts in this kind of discussions, but if not, I was wondering if somebody knows how to contact to discuss what was wrong.

You can also resubmit the scans and let the screeners know that you believe they made a mistake in declining the profile. Let the voters and screeners know why, which you have detailed in this post, and it wouldn't surprise me to see it be accepted this time.

Quoting Gamemaster:

Quote:
I've added better cropped covers which were a bit wider than the existing covers. In my opinion the quality was also a bit better. The colors were more natural and the covers were a little bit sharper.

Quoting the contribution rules:

Quote:
Before submitting new scans of cover art, make sure your new covers are of significantly higher quality than the existing online images...

I have not seen your contribution, but I do often see image contributions that are only marginally better. Could that have been a factor?

The OP stated that his scans were "a bit better".  A bit better is  not the same as signifantly higher in quality.  It is a known fact that the screeners compare the images and, if they don't see a significant improvement, will decline the new ones.

I am not saying that is what happened in this case, but it is possible.