ImageGear for C and C++ on Windows v20.0 - Updated
JBIG2
User Guide > File Formats and Compressions > File Formats > File Formats Reference > 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

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:

ImageGear Read Support:

ImageGear Write Support:

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.

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.

 

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