Fix bad image quality in dark images in iMovie I have an iMovie project (stop motion animation). Everything is fine, except for a dark scene. The photos get pixelated and blocked, and really ruined. The original image is very sharp and clear, yet the one in iMovie and the exported video files is ruined. 

The original media is not video. Rather, it is a large set of JPEG images (stop motion animation film). The images are 773 x 515 pixels, and very high quality. If it matters, it's being overlaid with M4A audio.

Other video editors (PiTiVi, Kdenlive) don't ruin it, so it's not a general issue.

Before iMovie:



In the final video:



Any ideas?
You need to set Data Rate in Export with Quicktime to Manual and increase Data Rate value for improving quality. You can also try compression quality after you have set a high data rate.