ART

• Extension: art
• Company: AOL
• Samples: http://samples.mplayerhq.hu/image-samples/ART/
• Wikipedia page: http://en.wikipedia.org/wiki/ART_image_file_format (has some interesting links)

ART is an image format used on the America OnLine (AOL) service. The file format originated with a company named Johnson-Grace and was later acquired by AOL. Allegedly, the format is able to employ a number of different compression techniques depending on the characteristics of the image data.

File Format

Integers seem to be in little-endian format.

0x00     (  +2) ASCII characters "JG", likely for Johnson-Grace
...
0x0D     (  +2) width
0x0F     (  +2) height

Format description

Patent 5,682,152 Data compression using adaptive bit allocation and hybrid lossless entropy coding

Patent 5,822,456 Optimal spline interpolation for image compression

Patent 5,892,847 Method and apparatus for compressing images