Working with the MRC Bitmap

LEADTOOLS offers the LEAD Mixed Raster Content object to handle mixed raster content files. This object enhances LEADTOOLS input/output functionality by adding support for color documents containing mixed image and text components. The Mixed Raster Content (MRC) format was developed by the International Telecommunications Union as part of ITU-T Recommendation T.44, and is defined in the proposed standard, RFC-2301, File Format for Internet Fax. The MRC model divides a page into strips and up to three layers: consisting of Mask, Foreground and Background layers. Each layer can be coded and compressed independently. Subsequently, these layers can be uncompressed and combined to restore the original image.

LEADTOOLS also provides support for PDF compression with MRC segmentation. This compression is used to break down a page or an image into smaller segments, saving each segment using compression appropriate for that segment. Thus, one page of a PDF file may have an image JPEG compressed, some text JBIG2 compressed, and another area CCITT compressed. This whole process works to provide a PDF file with better compression and better quality than just a standard Raster PDF file.

The LEADTOOLS implementation of the MRC model involves dividing an object into segments. A segment is a rectangular area on the bitmap that can be classified as text, grayscale, or picture, depending on the number of colors used in its area.

LEADTOOLS offers two methods for saving files: the Save method and the SaveT44 method. With these methods it is possible to save an MRC bitmap in any of the following modes:

MRC: This mode uses the Standard T44 file format. The default extension is *.MRC. Please note that multi-page files using this format can be loaded, but only one page can be saved. Use the SaveT44 method to save a file in this format.

LEAD MRC: This mode uses the LEAD proprietary T44 file format. The default extension is *.MRC. Please note that this is a single page file format. Use the Save method to save a file in this format.

TIF-MRC: This mode uses the Tagged Image Format and the Standard T44 format as a subtype. The default extension is *.TIF. Multi-page files using this format can be loaded and can also be saved. Use the SaveT44 method to save a file in this format.

TIF-LEAD-MRC: This mode uses the Tagged Image Format and the LEAD proprietary T44 format as a subtype. The default extension is *.TIF. Multi-page files using this format can be loaded and can also be saved. Use the Save method to save a file in this format.

The Standard T44 format file uses two different segment types: 1-bit Text and picture. The 1-bit text segments can be compressed using Fax G3 1D, Fax G3 2D, Fax G4 or JBIG compression and picture segments can be compressed using JPEG compression. Some of these compression schemes use a quality factor that allows the amount of compression to be controlled.

The LEAD proprietary MRC format uses the following segment types: 1-bit text, 2-bit text, 2-bit picture grayscale, 8-bit grayscale, and picture. The 1-bit text segments can be compressed using Fax G3 1D, Fax G3 2D, Fax G4 or JBIG compression. The 2 bit grayscale segments can be compressed using JBIG compression. The 8-bit grayscale segments can be compressed using JPEG, LEAD CMP or LEAD CMW compression, and pictures can be compressed using JPEG, LEAD CMP or LEAD CMW compression. Some of these compression schemes use a quality factor that allows the amount of compression to be controlled.

For more information refer to:

Loading Capabilities

Saving Capabilities

General Segmentation

Auto-Segmentation

Manual Segmentation

Auxiliary Elements