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. JBIG and JBIG2
JBIG and JBIG2 compression is included in LEADTOOLS Document, Vector, and Medical Imaging toolkits.
JBIG
JBIG defines a method for lossless compression encoding of a bi-level image (two color image). This method can also be used for coding grayscale and color images. LEADTOOLS now completely supports all three types of images, 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, LEAD now takes full advantage of all the functional blocks of this robust standard:
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.
The Adaptive Template Block provides real coding gain
for images rendered by grayscale with halftoning. This gain ratio approaches
80% in some situations.
The Typical Prediction Block speeds implementations
and provides some coding gain.
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.
The Deterministic Prediction Block provides good coding
gain when saving more than one resolution layer in the same file.
All the free parameters specified by the JBIG standard are applied in LEAD to achieve maximal compression and the highest speed for any saving or loading operation.
Support for the JBIG features is provided for the following programming interfaces:
JBIG2
The JBIG2 file format is a raster file format created by ISO/IEC 14492. This format is supported by Image Power. This format is an industry standard lossless, lossy and lossy to lossless compressed file format for bi-tonal (black and white) images. LEAD’s JBIG2 support handles the various flavor of generic region encoding/decoding procedure based on sequential coding of the image pixels using arithmetic coding (lossless). The generic region encoding/decoding procedure encodes/decodes a bitmap, treating it simply as an array of binary pixels. In order to achieve highest compression ratios available by the generic region encoding procedure of JBIG2 format, LEAD also takes full advantage of all the functional blocks of this robust standard including the Adaptive Arithmetic Encoder, the Adaptive Template Pixels, and the Typical Prediction Block. Saving images in a JBIG2 format results in smaller image files sizes when compared to other industry standard compressed formats such as JBIG, CCITT G3 or G4. JBIG2 can compress bi-tonal images 2 - 5 times more than the same image compressed with the CCITT G4 compression.
Support for the JBIG2 features is provided for the following programming interfaces: