JPEG techniques improve image compression

Spearheaded by high-technology companies, such as Alcatel, Canon, Ericsson, Kodak, Mitsubishi, and Motorola, the JPEG2000 standard provides a coding system based on the wavelet transform.

Apr 1st, 2002

Spearheaded by high-technology companies, such as Alcatel, Canon, Ericsson, Kodak, Mitsubishi, and Motorola, the JPEG2000 standard provides a coding system based on the wavelet transform.

In 1987, the JPEG compression standard was created to fit an image's data on a floppy disk. Now, demands for capturing, sending, and receiving complex images have pushed the original JPEG specifications beyond their capacity. Spearheaded by high-technology companies, such as Alcatel, Canon, Ericsson, Kodak, Mitsubishi, and Motorola, the JPEG2000 standard provides a coding system based on the wavelet transform. Already, proponents of the standard are describing uses that range from digital cameras to prepress production and medical imaging applications.

Last year, Analog Devices (Norwood, MA) became the first company to offer specific hardware to implement the JPEG2000 standard with the introduction of its DV-JP2000 processor. Capable of compressing five 3-Mpixel images in 1 s, the ADV-JP2000 provides lossless compression of images of up to 10 bits/component and lossy support of up to 14 bits per component. This capability compares favorably with the original JPEG standard, which offered only 8 bits/component and did not support both lossless and lossy compression in a single format.

Companies enter market
Now, other companies are set to enter the JPEG2000 hardware market with hardware, coreware, and DSP-based solutions. These include the JPEG2000 encoder core from inSilicon (San Jose, CA) that supports both lossless and lossy compression applications through the implementation of the reversible 5/3 wavelet transform.

Amphion Semiconductor (San Jose, CA) also has announced the CS6210 core for still image and video-compression systems where frame-based coding is required. Compliant with JPEG2000, this core provides a row-based wavelet transform for the 9/7 irreversible and 5/3 reversible wavelet filter bank. Other as yet unannounced hardware products are also being readied by CAST Inc. (Woodcliff Lake, NJ), which expects to have a complete JPEG2000 core later this year, and WIS Technologies (San Jose, CA), which offers its WIS Impressionist software for JPEG2000.

Currently the dominant compression technique for still images, JPEG is based on discrete cosine transforms, which can cause image degradation. Based on transform coding from the spatial domain to the frequency domain, JPEG2000 also causes noise when images are highly compressed.

To overcome these flaws, Ohmi Laboratories at Tohoku University (Sendai, Japan) and Sharp Corp. (Mahwah, NJ) have jointly developed a vector quantization still-image compression technology that generates no noise using an adaptive-resolution alteration-processing technique. According to Sharp officials, this technique also can limit the generation of the block noise common in vector quantization, which results in a performance difference of 5 to 10 dB in terms of image quality.

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