Compression of earth science data with JPEG2000

With the increased use of remote sensing, the need for efficient transmission of such data has gathered greater importance in recent times. Remote sensing images are typically large and are often multispectral or hyperspectral in nature. Hyperspectral imaging sensors generate data at hundreds of wavelengths simultaneously, resulting in very large data sets. Transmission of such earth science data over bandwidth-limited channels requires the employment of compression technology. JPEG2000 is the latest international standard for image compression [1,2]. It offers many advantages over earlier image compression standards. Perhaps the most important advantage offered by JPEG2000 is that it is designed to act as an image processing system rather than as just an inputoutput image compression filter. That is, unlike earlier image compression standards, decisions regarding image quality, compression ratio and image resolution need not be made at compression time. With JPEG2000, such decisions can be made after compression. This provides tremendous flexibility and facilitates the adaptation of the standard to specific imaging applications. The JPEG2000 standard is published in several parts. Part I describes the minimal compliant decoder and the codestream syntax. Part II consists of "value-added" technologies that improve the performance for some applications. Other parts of the standard define extensions such as those defined in Part III (referred to as Motion JPEG2000) for enabling the use of the standard with video sequences and the JPEG2000 Interactive Protocol (JPIP) defined in Part IX. Our goal here is to provide a brief overview of the standard and its capabilities as it relates to compression of earth science data. Thus, we will only discuss the relevant sections of the standard. For a comprehensive discussion of the standard, the interested reader is referred to [2,3]. The rest of this chapter is organized as follows: Section 2 provides an overview of the JPEG2000 standard. Although the standard specifies only the decoder and codestream syntax, this section focuses on the description of a representative encoder, since this makes the description more comprehensible. In Section 2, we discuss both Part I and Part II of the standard as they relate to encoding of earth science data. Part II of the standard specifies additional functionalities that are particularly important for compression of earth science data. In Section 3, we present methods that enable scan-based processing of JPEG2000. Since remote sensing data are often captured incrementally by sensors in a push-broom fashion, scan-based processing enables efficient implementation of the standard.