Technology Info See the JPEG entry at Wikipadia Standards home pages: • JPEG • JPEG-LS • JPEG 2000 Observations from JPEG 2000 engineer Michael Gormish CAST/Avnet DesignCon 03 paper: A New Reference Design Development Environment for JPEG 2000 (Download Presentation) News Releases 06/10/02 CAST JPEG 2000 Encoder Core Provides Fast, Flexible Image Compression 02/04/04 CAST Introduces Flexible Family of JPEG IP Cores 01/31/05 CAST Introduces the First Lossless JPEG (LJPEG) IP Cores 06/13/05 Creo Uses CAST IP Cores in Advanced Leaf Aptus Digital Camera Backs Customer Applications Creo (now Kodak) uses this core for fast, full-fidelity photo capture in their high-end Leaf® Aptus digital camera backs for professional photographers

Image Compression Standards and Cores

Image compression is a complex application. CAST and our development partner Alma Technologies have invested heavily over the past several years to build expertise and develop a broad line of reusable image compression products. We believe we now offer the most complete, easiest to use, and highest quality JPEG-related IP cores.

This page intrduces those cores, with links to their individual datasheet pages. It discusses factors in choosing the best core for your application, and leads to galleries illustrating differences among the image compression standards. It also includes lins to further resources for learning about the field.

CAST Image Compression Cores Family

Our family of JPEG image compression IP cores includes:

• JPEG — baseline ISO/IEC 10918-1 JPEG standard
  Lossy compression standard with good quality, allows trading off file size and image quality
  • JPEG-E Baseline JPEG Encoder Core
  • JPEG-D Baseline JPEG Decoder Core
  • JPEG-C Baseline JPEG Codec Core
• Lossless JPEG (LJPEG) — lossless encoding mode (SOF3) of the ISO/IEC 10918-1 standard
  Lossless compression for somewhat smaller files with original image quality
  • LJPEG-E Lossless JPEG Encoder Core
  • LJPEG-D Lossless JPEG Decoder Core
• JPEG-LS — ISO/IEC 14495-1 JPEG standard
  Fast lossless compression for somewhat smaller files with original image quality
  • JPEGLS-E JPEG-LS Encoder Core
• JPEG 2000 — implements the computationally intensive part of the ISO/IEC 15444-1 standard
  Lossless and lossy compression for high image quality and small file versatility in a single core
  • JPEG2K_E JPEG 2000 Encoder Core
  • JPEG2K_D JPEG 2000 Decoder Core

Choosing Among Image Compression Cores

JPEG

JPEG is the oldest and most prevalent form of still image compression, proposed as a standard in 1992. It has found a second life due to the Internet and digital cameras showing up in everything from home security to cell phones.

JPEG is a "lossy" type compression. meaning that image details are thrown away to acheive a file size suitable for the application at hand. While every attempt is made to disguise the loss by throwing away frequencies to which the human eye is not sensitive, there is a noticeable degradation in quality as compression ratios become larger. At low compression ratios, the quality of a JPEG image can be more than acceptable, bordering on the quality offered by lossless techniques.

Compare, for example, these images produced by our JPEG Encoder core. The 20:1 compression ratios yields a very good looking image and a significantly smaller file. The 75:1 compression yields a very small file. Its output image doesn't look that great, but may be of sufficient quality for applications with very low bandwidth requiring small file sizes.

Being a "tried and true" technology the emphasis of our core is on small size, high throughput and, especially, ease of integration and use. No external processing is required by our core to handle even the most demanding applications. A bit rate control mechanism is also available JPEG can handle almost any size and type of image with the only restriction being that it can only process a sample size of 8 bits. Therefore, certain types of images cannot be processed and a different kind of compression technique is needed.

LJPEG

LJPEG was proposed in late 1993 as a part of the original JPEG standard. It recognizes that a "lossless" form of compression is required for some applications.

Here "lossless" doesn't mean just "very good quality." Instead, true lossless means that one can decompress an encoded image such that a bit-for-bit replica of the original image is produced. The LJPEG cores we offer follow this standard and allow encoding and decoding of images with pixel depths up to 16 bits in a true lossless format.

These cores perform lossless compression and decompression in the smallest possible hardware footprint, and with maximum processing throughput. An example application for this technology would be a professional digital camera where on-board image storage requires compressed images as well as quick retrieval of said images for local review.

JPEG-LS

JPEG-LS is a newer (1999) form of pure lossless compression that uses more modern algorithms than LJPEG to achieve the same goal.

The benefit here is that the compression achieved is slightly greater and the throughput better at the price of a slight increase in core size. Like the LJPEG it can handle up to 16 bit pixel depths.

JPEG 2000

JPEG2000 is the newest technology in still image compression. It has the advantage of being capable of doing both lossless and lossy compression using new algorithms to achieve higher image quality than JPEG when doing lossy compression and roughly the same amount of lossless compression as the JPEG-LS. It handles 16 bit pixel depths. It incorporates a very sophisticated rate control mechanism that is far superior to that of the original JPEG. It is the ultimate in still image technology. The price for this level of sophistication is in the size of the core with a slight throughput penalty, but for many newer applications the improvements are well worth it. A good example of such an application is satellite imagery where image types vary and bandwidth control is a must.

They say a picture is worth a thousand words so follow this link to a gallery of images that shows exactly what we are talking about..