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Overview

This document describes how the IJG code was modified.
Base version of the IJG code is 9c. (Not the latest)

The changes were made from the following three points.

  • Remove unused functions and files.
  • Add extension functions.

Remove unused

Remove unused files

The following files are removed.

  • makefile, config files and project files for another systems
  • files for unused functions
    image reader, image writer, DCT, iDCT, command line interface...

Remove unused functions

Modified jmorecfg.h for removing unused functions.
Some #define are commented out.

Add extension functions

Pixelization (block)

The function makes 8x8 pixelization.
The function is implemented as the do_pixelize() function in transupp.c.
The function is based on do_wipe() function.
do_wipe() clears all DCT coefficient to fill block with gray color.
do_pixelize() clears AC coefficients only, this causes 8x8 pixelization.

Pixelization (MCU)

The function makes pixelization in MCU unit.
The function is implemented as the do_pixelize2() function in transupp.c.
The function is based on do_pixelize(), block pixelization function.
do_pixelize() clears AC coefficients in a block.
In addition to that, do_pixelize2() averages DC coefficient in MCU.