Chapter 10: Processes of Perception and Analysis

Section 6: Irreversible Data Compression

JPEG compression

In common use since the early 1990s JPEG compression works by first assigning color values to definite bins, then applying a discrete Fourier cosine transform, then applying Huffman encoding to the resulting weights. The "quality" of the image is determined by how many weights are kept; a typical default quality factor, used say by Export in Mathematica, is 75.

From Stephen Wolfram: A New Kind of Science [citation]