JBIG

(Document/Medical only) JBIG is an acronym for 'Joint Bi-level Image experts Group'. This was a group of experts nominated by national standards bodies and major companies to work to produce standards for bi-level image coding.

The JBIG group has developed IS 11544 (ITU-T T.82) standard for the lossless compression of a bi-level image. It can also be used for coding grayscale and color images with limited numbers of bits per pixel. It can be though to be similar to Group 3 or Group 4 fax, offering between 20% and 80% improvement in compression over these methods. JBIG compression averages about a 20:1 over the original uncompressed image.

LEADTOOLS completely supports all three types of images (bitonal, grayscale and color), giving you the ability to make full use of this powerful compression technology. LEADTOOLS also supports the progressive capability of JBIG, allowing you to store and send multiple representations of images at different resolutions without any extra storage overhead.

To achieve the highest compression ratios available in the JBIG format, LEADTOOLS takes full advantage of all the functional blocks of this robust standard:

image\sqrblit.jpg The Adaptive Arithmetic Encoder, which presents the heart of this format, has the ability to predict and hence encode future data symbols based on the data which is being currently encoded.

image\sqrblit.jpg The Adaptive Template Block provides real coding gain for images rendered by grayscale with halftoning. This gain ratio approaches 80% in some situations.

image\sqrblit.jpg The Typical Prediction Block speeds implementations and provides some coding gain.

image\sqrblit.jpg The Resolution Reduction Block is used to get a lower resolution version of an image so that no loss of data is encountered. This is mainly important for bi-level images, to avoid any deletion of thin lines.

image\sqrblit.jpg The Deterministic Prediction Block provides good coding gain when saving more than one resolution layer in the same file.

The LEADTOOLS JBIG features are available in the following products:

LEADTOOLS Document Imaging

LEADTOOLS Document Imaging Suite

LEADTOOLS Medical Imaging Suite

Support for the JBIG features is provided for the following programming interfaces:

ActiveX

API

Class Library

COM

.NET

VCL