Dictionary Image Format

What is the Dictionary Image Format (DIF)?

The Dictionary Image Format is a plaintext image format that can be compressed using gzip that can store bitmap images. It is not dissimilar from the XPixMap format.

Why and When Should I Use the DIF Format?

Why?

The DIF Format is a good image format for programmers, because it isn't too hard to implement. Compressed DIF Images also serve the same purposes as GIF, except that there is no 256 color limitation.

When?

Uncompressed, raw DIF files can be quite large, in the megabytes. Because of this reason, it is not reccomended to store photographic images in the DIF format. The DIF file format also does not support transparency.

If possible, it is reccomended to store images with high resolutions as compressed DIFs. In some cases, the space savings by using compression can be huge. Take this image as an example. In raw DIF format, it is 6.86 MB. Compressed, it is only 52.6 KB (the size of the PNG file is 43.5 KB). DIF uses lossless compression.

It is also very important to know that the current DIF specification does not support transparency. It also does not define how images with transparent regions should be converted to DIF.