Thank you, guys. Here's something I found out: most of the time I create a non-compressed .mov out of the image sequence, which is quite large. I then create a H264 movie out of that with the Adobe media encoder to make the file smaller. Nevertheless the movie looks washed out. The contrast is low, no matter what I try. Even with other QT-codecs I get the same results. this seems to be very common on windows machines as I read in several forums.
But I found out that when you play the movie with another player like the classic media player it looks as good as the source movie. So it seems to be a QT-player issue. I uploaded the
H264.movie to vimeo and the contrast was OK (the quality on vimeo is terrible, but that's something else...)