Included in LEADTOOLS Document Imaging V15 LEADTOOLS JBIG Module
JBIG defines a method for lossless compression encoding of a bi-level image (that is, an image that, like a black-and-white image, has only two colors). This method can also be used for coding grayscale and color images.
"PROGRESSIVE " capability :
When decoding a progressively coded image, a low-resolution version of the original image is made available first with subsequent doublings (twice the width and height) of resolution as more data is decoded. Note that resolution reduction is performed from the higher to lower resolution layers, while decoding is performed from the lower to higher resolution layers.Progressive encoding has two distinct benefits:
I- One is that with them it is possible to design an application with one common database that can efficiently serve output devices with widely different resolution capabilities. Only that portion of the compressed image file required for reconstruction to the resolution capability of the particular output device has to be sent and decoded. Also, if additional resolution enhancement is desired, for example, a paper copy of an image already on a CRT screen, only the needed resolution-enhancing information has to be sent.
II-The other benefit of progressive encodings is that they can provide subjectively superior image browsing (on a CRT) for an application using low-rate and medium-rate communication links. A low-resolution rendition is transmitted and displayed rapidly, and then followed by as much resolution enhancement as desired. Each stage of resolution enhancement builds on the image already available. Progressive encoding can make it easier for a user to quickly recognize the image as it is being built up, which in turn allows the user to interrupt the transmission of the image (Internet applications).
JBIG, Power of Compression:
- The main purpose behind JBIG is to replace the less efficient compression algorithms used by CCITT Group3 & Group4.
- For scanned images of printed text or line art the compression ratio of JBIG is (10 –50) % greater than that of Group4.
- 500% greater than Group4 for computer generated images of printed text.
- 2 to 30 times better for images with grayscale rendered by half-toning or dithering.
- JBIG is sensitive to noise, the compression ratio decreases when the amount of noise in your image increases.
- JBIG can be used as an alternative to lossless JPEG. JBIG produces better results than lossless JPEG on images with two to five bits per pixel and produce identical results on image with data six to eight pixels.
- Cost Savings from 20-60% Smaller Files : Cost savings come from several areas. JBIG's smaller files lead to fewer optical disks for storage, less network bandwidth, and faster transfer of files.
Where can JBIG be used?
- Document imaging: electronic scanning, storage, and management of paper-based documents.
- Banking applications.
- Internet applications or even any network related applications.
- Storing A0 sized engineering documents. Multiple resolution layers can be stored so that the user can browse through using a low resolution preview and then display the image at the desired resolution.
SAMPLE JBIG COMPRESSION RATIOS
NOTE :" Compression Ratio " field which appears in the table is evaluated as follows :
Compression Ratio = (1- ( (JBIG Compressed Size) /( Size In Memory) ) ) *100
Where a 100% compression ratio means that the compressed size of the image is zero
CCITT Image
Image Dimensions
Size In Memory (Bytes)
JBIG Compressed Size(Bytes)
Compression Ratio
IMAGE 1 1728X2376
513216
14857
97.1 %
IMAGE 2 1728X2376
513216
8679
98.3 %
IMAGE 3 1728X2376
513216
22163
95.7 %
IMAGE 4 1728X2376
513216
54523
89.4 %
IMAGE 5 1728X2376
513216
26012
95.0 %
IMAGE 6 1728X2376
513216
14422
97.2 %
