The JPEG spec is a bit on the verbose side, and most of it can be skimmed easily; for example, one of the sentences near the beginning is "An encoder is an embodiment of an encoding process." There's also specifications of lossless modes and arithmetic compression, which you probably don't care about for a first exercise; the "baseline DCT" is the only variant that really matters. The spec is nearly 200 pages, but the diagrams and flowcharts take up a significant amount of that space.
Interestingly enough, the JPEG2000 spec is at first glance not that much longer, but it is far more terse, so the size of the spec is only a rough estimate of the complexity and work it'd take to implement.
Interestingly enough, the JPEG2000 spec is at first glance not that much longer, but it is far more terse, so the size of the spec is only a rough estimate of the complexity and work it'd take to implement.