ccitt-t4-t6

This crate aims to implement the T.4 and T.6 standard of the ITU’s Telecommunication Standardization Sector (ITU-T). These documents decribe a family of encoding/decoding algorithms for monochrome i.e. black-and-white bitmaps, which have been created for fax machines.

They are also used in the Adobe PDF file format for the encoding of monochrome bitmap images as the /CCITTFaxDecode stream filter.

State of implementation

This crate currently implements an Encoder and a Decoder for the Group 4 2D coding scheme specified in T.6. This is sufficient for creating PDF documents that use CCITTFaxDecode to draw Type3 font glyphs. If you want to support non-negative values of the K decode parameter, i.e. Group 3 encoding, feel free to submit a Pull Request.