Lenpeg

LenPEG is an image compression algorithm presented as a satirical take on the pursuit of ever-higher compression ratios within the image processing community. Rather than being a programming language, LenPEG is described as an algorithm focused on achieving maximal, lossless compression for test images, particularly the standard Lenna image widely used for benchmarking. The tool's design principles include maintaining backward and forward compatibility with other, so-called inferior image compression algorithms.

The core concept of LenPEG is that if the input image is the canonical Lenna, the algorithm compresses it to a single bit, achieving an extremely high lossless compression ratio. For any other image, LenPEG prompts the user to select another compression algorithm such as GIF, JPEG, or PNG, then prepends a marker bit to the output, indicating the use of that algorithm. Decompression follows a similar logic: if the file's magic number is zero, Lenna is displayed; otherwise, the initial bit is dropped, and the chosen compression algorithm is used to restore the image.

Several iterations of LenPEG are described, each humorously claiming even greater efficiency. LenPEG 2, credited to Tuomas Heino, further compresses the Lenna image to an empty file, theoretically achieving an infinite compression ratio, while handling other images similarly to the original version but with one bit less overhead. LenPEG 3 takes the satire further by deleting all non-essential data from the computer when compressing the Lenna image, thereby freeing storage space and rendering the compression ratio dependent on the hardware's total capacity. Each version is described with tongue-in-cheek analysis of its superiority over previous approaches.

LenPEG is aimed at an audience familiar with image compression standards and the conventions of algorithm benchmarking, particularly those aware of the Lenna image's role in the field. The algorithm is described in detail on its web page, but no information is provided regarding implementation, software delivery, pricing, or licensing. Its primary purpose is to parody and critique the relentless quest for marginal gains in compression algorithms.