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FEATURE

JPEG2000 Image Compression

A Real-Time Processing Challenge

by Jill Hunter and Moira Wylie

April 2003

The rising standard for image compression, JPEG2000 not only offfers better image quality in smaller file sizes but also some new features for digital imaging...

Building on the momentum of the established JPEG standard-the principal technology for photographic images on the Web-the acceptance of JPEG2000 in the digital imaging marketplace is rapidly gathering pace. We once again examine this new standard, first covered in detail in AI's May 2001 issue, as well as describe a hardware accelerator architecture that meets the real-time image processing demands of a multiplicity of embedded JPEG2000 applications.

The phenomenal expansion of digital imaging applications has created the need for a modern, standardized and flexible file format for the storage and transmission of digital images. The JPEG2000 standard has emerged in response to this requirement and is the current state of the art for compression performance in still images. The standard is wavelet-based and supports much higher compression ratios than its predecessor, JPEG, which was released in 1989. It also supports much greater bitstream flexibility for progressive access of images in many networked and point-to-point communications systems.

The JPEG2000 algorithm is rather more complex than JPEG and requires a high performance implementation to support real-time imaging systems for both the consumer and industrial markets. Despite the implementation challenges, JPEG2000 is one of the new multimedia standards driving the future growth of the digital multimedia industry.

WHY MOVE TO JPEG2000?
The original JPEG image coding standard has been a great success, with the JPEG format used widely for Internet, digital photography and multimedia desktop publishing. However, following the completion of the DCT-based standard, many advances have been made in image coding such as wavelet and subband-based technologies. Many limitations have also been identified in the JPEG standard. It is now recognized that such shortcomings include severe blocking effects at low bit rates and high compression ratios, insufficient support for scalability (both in terms of image size and image quality), the absence of accurate rate control and a lack of support for error resilience.