JBIG2

Full Name	JBIG2 (bilevel image compression)
Format ID	IG_FORMAT_JB2 = 62
File Extension(s)	*.jb2
Data Type	Raster Image
Data Encoding	Binary
Color Profile Support	No
Multi-Page Support	Yes
Alpha Channel Support	No
ImageGear Platforms Support	WIN32

To support the JBIG 2 format, attach the ImageGear JBIG2 Component to Core ImageGear. See Attaching Components.

ImageGear Supported Versions:

N/A

ImageGear Supported Features:

IG_FLTR_DETECTSUPPORT - autodetection
IG_FLTR_PAGEREADSUPPORT - single page file reading
IG_FLTR_PAGEINSERTSUPPORT - single-page file writing
IG_FLTR_MPAGEREADPSUPPORT - multi-page file reading

ImageGear Read Support:

IG_COMPRESSION_JBIG2 - Indexed RGB: 1 bpp

ImageGear Write Support:

IG_COMPRESSION_JBIG2 - Indexed RGB: 1 bpp

ImageGear Filter Control Parameters:

Filter Control Parameter	Type	Default Value	Available Values	Description
JBIG2_FILE_ORG	INT	IG_JB2_FILEORGDISTRIBUTED = 0	G_JB2_FILEORG_SEQUENTIAL = 0 IG_JB2_FILEORG_RANDOMACCESS = 1	This function specifies the file format generated by the encoder. IG_JB2_FILEORGDISTRIBUTED creates a sequential document suitable for transmission. IG_JB2_FILEORGCENTRAL creates a document that allows random access to the pages in the document. JBIG2 files may be organized in two ways; by sequential access or by random access. In sequential organization (IG_JB2_FILEORGDISTRIBUTED), each page's header immediately precedes the page’s data. In random access organization (IG_JB2_FILEORGCENTRAL), all page headers are collected together at the beginning of the file, followed by the data for all of the segments in the same order. The second organization permits a decoder to determine all the segment dependencies without reading the entire file. Sequential organization is suitable for transmitting images through a network - page by page. Random access organization is used for quick access to each page in an image.

Filter Control Parameter

Type

Default Value

Available Values

Description

JBIG2_FILE_ORG

INT

IG_JB2_FILEORGDISTRIBUTED = 0

G_JB2_FILEORG_SEQUENTIAL = 0
IG_JB2_FILEORG_RANDOMACCESS = 1

This function specifies the file format generated by the encoder.

IG_JB2_FILEORGDISTRIBUTED creates a sequential document suitable for transmission.
IG_JB2_FILEORGCENTRAL creates a document that allows random access to the pages in the document.

JBIG2 files may be organized in two ways; by sequential access or by random access.

In sequential organization (IG_JB2_FILEORGDISTRIBUTED), each page's header immediately precedes the page’s data.
In random access organization (IG_JB2_FILEORGCENTRAL), all page headers are collected together at the beginning of the file, followed by the data for all of the segments in the same order.

The second organization permits a decoder to determine all the segment dependencies without reading the entire file. Sequential organization is suitable for transmitting images through a network - page by page. Random access organization is used for quick access to each page in an image.

Comments:

The JBIG2 format supports multi-page images and is the most effective compression method for bitonal (B\W) images. JBIG2 Format Filter supports some features of bitonal file processing. These features are determined by IG_FLTR_ flags. This Format Filter also allows you to save JBIG2 images with different compressions depending of image bit depth.

JBIG2 is a highly-compressed black and white image format that uses symbol recognition and substitution for very good compression results. Any black and white image can be compressed using JBIG2 including images stored as Group 4, Group 3, MO:DCA, TIFF, PDF and others.

The JBIG2 compression algorithm searches for groups of pixels arranged in similar shapes and use them to define a symbol. Rather than retaining information on the placement of each pixel, a table is created for common symbols. This allows users to see incredible reductions in file sizes. Compression rate matches 100:1 compared to uncompressed black and white TIFFs.