J is for JPEG: Windows bitmap to JPEG baseline compression

JPEG baseline is one of the world's most used compression algorithms. This is because it is fast, offers good compression with little noticeable image degradation and allows the user to specify the level of image quality. The algorithm uses a number compression techniques such as difference, run-length and Huffman coding. It also does a number of image manipulation functions such as colour space conversion and changing from the spatial to the frequency domain. This paper explains the algorithm in detail as well as giving code for a J implementation. The implementation given compresses 24-bit Windows bitmap images. Also provided is a brief explanation and code implementation of JFIF (JPEG File Interchange Format). The result is an implementation that runs in a similar time as implementations in compiler based languages.