Constant quality JPEG2000 rate control for digital cinema

摘要

An uncompressed Digital Cinema Distribution Master (DCDM) image typically has dimensions of up to 4096x2160 (4K) or 2048x1080 (2K) with 12-bit pixel data for each of the X'Y'Z' color planes. At a frame rate of 24 frames per second, this gives uncompressed data rates of 7.6 and 1.9 Gbps for 4K and 2K respectively. Even after compression, average data rates in the hundreds of Mbits/sec. are encountered. Recently, the Society of Motion Picture and Television Engineers' (SMPTE) has chosen JPEG2000 as the standard to be used for digital cinema compression. Thus, methods to appropriately trade off rate and quality for JPEG2000-compressed movies will have high importance in the next several years as systems are designed and deployed. In this paper we describe a new distortion-based framework for rate control that enables a JPEG2000 encoder to achieve a user-specified quality, and therefore makes it possible to produce constant quality from frame-to-frame in an image sequence. The new method makes direct use of the same JPEG2000 coding pass data as the traditional approaches, and thus can easily be adopted at the back end of JPEG2000 encoding engines. We compare the new method with two other common rate control techniques for JPEG2000.