Software-Based JPEG Compression Using SH RISC Microcomputers

Hiroshi Takeyama, Semiconductor & Integrated Circuits Division, Hitachi, Ltd.
Koichi Tamura, Hitachi Yonezawa Electronics Co., Ltd.
Takashi Shudo, Hitachi Microcomputer System, Ltd.


Image compression technology is a key element for meeting the increasing demands on multimedia applications and equipment. Current image processing systems use several compression technologies, including Moving Picture Experts Group (MPEG), H.261, and Joint Photographic Experts Group (JPEG). Of these, JPEG, which is used for still-picture processing, became an international standard in 1993.

With the major part of image processing consisting of operations on vectored values, there is an inherent need for high-speed computation. Up until now only a combination of dedicated LSIs and a signal processor was able to handle such processing requirements.

Recently, however, improved CPU performance has made it possible to perform in software the kind of processing (of images, speech, communications, etc.) that could previously be handled only by dedicated LSIs and signal processors.

With the development of a new series of microcomputers (SH series), which employ a reduced instruction set computer (RISC) CPU, it is now possible to perform JPEG processing in software. Using this approach, both JPEG processing and system control can be handled by an SH microcomputer, making it possible to construct a highly flexible system at low cost.

Active development of such software (middleware) for SH series microcomputers is expected to be carried out in the future.

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