Summary of JPEG Baseline
The baseline system provides efficient lossy image compression. It supports four color components simultaneously, with a maximum number of eight input bits for each color pixel component.

The basic data entity is a block of 8 x 8 pixels. However, this block can represent a large subsampled image area (for example, subsampled by decimated chrominance signals). The blocks of the different color components are sent interleaved, thereby allowing the decoder to create the decompressed image and translate back to the original color space on-the-fly.