The fractal transform is a technique invented by Michael Barnsley et al. to perform lossy image compression.
This first practical fractal compression system for digital images resembles a vector quantization system using the image itself as the codebook.
Then copy blocks from A2 to A1 as directed by the compressed data, multiplying by the respective gains and adding the respective color offsets.
In fact, a slight modification of the decompressor to run at block sizes larger than 4x4 pixels produces a method of stretching images without causing the blockiness or blurriness of traditional linear resampling algorithms.
The basic patents covering Fractal Image Compression, U.S.