The JPEG 2000 still image compression standard - IEEE Signal Processing Magazine

The development of standards (emerging and established) by the International Organization for Standardization (ISO), the International Telecommunications Union (ITU), and the International Electrotechnical Commission (IEC) for audio, image, and video, for both transmission and storage, has led to worldwide activity in developing hardware and software systems and products applicable to a number of diverse disciplines [7], [22], [23], [55], [56], [73]. Although the standards implicitly address the basic encoding operations, there is freedom and flexibility in the actual design and development of devices. This is because only the syntax and semantics of the bit stream for decoding are specified by standards, their main objective being the compatibility and interoperability among the systems (hardware/software) manufactured by different companies. There is, thus, much room for innovation and ingenuity. Since the mid 1980s, members from both the ITU and the ISO have been working together to establish a joint international standard for the compression of grayscale and color still images. This effort has been known as JPEG, the Joint Photographic Experts Group. (The “joint” in JPEG refers to the collaboration between ITU and ISO; see Fig. 1). Officially, JPEG corresponds to the ISO/IEC international standard 10928-1, digital compression and coding of continuous-tone (multilevel) still images or to the ITU-T Recommendation T.81. The text in both these ISO and ITU-T documents is identical. The process was such that, after evaluating a number of coding schemes, the JPEG members selected a discrete cosine transform(DCT)-based method in 1988. From 1988 to 1990, the JPEG group continued its work by simulating, testing and documenting the algorithm. JPEG became Draft International Standard (DIS) in 1991 and International Standard (IS) in 1992 [55], [73]. With the continual expansion of multimedia and Internet applications, the needs and requirements of the technologies used grew and evolved. In March 1997, a new call for contributions was launched for the development of a new standard for the compression of still images, the JPEG 2000 standard [28], [29]. This project, JTC 1.29.14 (ISO/IEC 15444-1 or ITU-T Rec. T.800), was intended to create a new image coding system for different types of still images (bilevel, gray level, color, multicomponent), with different characteristics (natural images, scientific, medical, remote sensing, text, rendered graphics, etc.) allowing different imaging models (client/server, real-time transmission, image library archival, limited buffer and bandwidth resources, etc.) preferably within a unified system. This coding system should provide low bit-rate operation with rate distortion and subjective image quality performance superior to existing standards, without sacrificing performance at other points in the rate-distortion spectrum, and at the same time incorporating many interesting features. One of the aims of the standardization committee has been the development of Part I, which could be used on a royaltyand fee-free basis. This is important for the standard to become widely accepted, in the same manner as the original JPEG with Huffman coding is now. The standardization process, which is coordinated by the JTC1/SC29/WG1 of ISO/IEC (Fig. 1) has already (since December 2000) produced the International Standard (IS) for Part I [41]. In this article the structure of Part I of the JPEG 2000 standard is presented and performance comparisons with established standards are reported. This article is intended to serve as a tutorial for the JPEG 2000 standard. In the next section the main application areas and their requirements are given. The architecture of the standard follows afterwards, with the description of the tiling, multicomponent transformations, wavelet transforms, quantization and entropy coding. Some of the most significant features of the standard are presented next, such as region-of-interest coding, scalability, visual weighting, error resilience and file format aspects. Finally, some com-