Hardware JPEG
Chips that did baseline JPEG in hardware were reasonably popular during the early 90's. I did several designs back then based on the C-Cubed CL550, the Zoran 36020/40, and the LS647xx series from LSI. The advantage of using dedicated hardware was speed, they were at least an order of magnitude faster than DSP-based solutions at the time. I doubt that any of these chips are still available or supported, but here's a link to a few more dedicated JPEG chips (DCT processors & back end encoders) if you want to try tracking them down:
http://www.faqs.org/faqs/compression-faq/part3/
Very few of these were all in one JPEG chips (CL550 and ZR36040 being the exceptions). Most came as chipsets, with a DCT codec and a separate back end for zig-zag/quantization & huffman coding. Most chipsets also had an optional front end chip for doing color space conversions.
If you have a second or more for processing, consider using a DSP-based solution, it's much more flexible and can be updated easily :wink:. Well, easier (ex; going from DCT to wavelet compression). Highly optimized baseline JPEG code exists for a number of DSPs, especially those from TI.