Imagic Film/Picture
From Just Solve the File Format Problem
An Imagic picture is a raster graphic in a format used by the Atari ST series in conjunction with animation. It can be compressed or not, and low, medium, or high-res. The file extension .ic1 is used for low-res, .ic2 for medium, and .ic3 for high. Compressed image data may also be "delta compressed", where it is stored as a set of differences from a reference image (in a separate file named within the headers of the current one). This is commonly used for animation frames.
Identification
Files start with the ASCII string IMDC
. The following word is 0, 1, or 2 for low, medium, and high-res respectively.