The standardization of color photographic image data compression

Abstract

Members of the International. Standards Organization ISO/IEC JTC1/SC2 Working Group 8 (Coded Representation of Picture and Audio Information) and the Consultative Committee of the International Telegraph and Telephone (CCITT) Study Group VIII Special Rapporteur Group on New Forms of Image Communication have been working together during 1987 and 1988 in a Joint Photographic Experts Group (JPEG) for the purpose of developing an international standard for the compression and decompression of natural color images. The technique selected is required to allow for both progressive and sequential image buildup during decompression. Decompression is to be feasible in real time in the ISDN environment (64 Kbits compressed data per second). The final standard is expected to produce a recognizable image at under 0.25 bits/pixel, an excellent image around 0.75 bits/pixel, and an image visually indistinguishable from the original around 3 bits/pixel for original images of 16 bits/pixel. Exact (lossless) coding is also required. An adaptive discrete cosine transform (DCT) technique was selected in January 1988 for further refinement and enhancement. The definition of the inverse DCT, how to improve the low-bit-rate image quality, the choice of entropy coding technique, and the method of achieving graceful progression are being studied as part of the refinement and enhancement process before final selection. A draft standard is expected to be available during 1989. The status of the refinement process will be reviewed. © 1989 SPIE.