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What is this

Jpegtran extension for lossless pixelization. The goal of this repository is providing blur operation without loss.

What is Jpegtran

Jpegtran is a command line program which can exetute the following operations to JPEG image without loss.

  • Crop
  • Rotate (90,180,270 degrees)
  • Flip (horizontal,vertical)
  • To Grayscale

It is a part of the IJG(Independet JPEG Group) code.

File list

  • ChangesIJG.md
    This file describes the changes from the original IJG code.
  • License.md
    License terms for this codes

How to build

Execute makefile. Attached makefile is for cygwin with mingw64. Modify it to your development environment.

Usage

The general options are same as Jpegtran.
The following options is not compiled.

  • -progressive
  • -arithmetic
  • -scan

Pixelization option is exclusive of other transfromation option, crop, rotate, flip....

Extension opition format is below.
-pixelize (width)x(height)+(posx)+(posy)@(blkX)@(blkY)[a]
This option can be specified multiple times, maximum 8. It can be changed by modify line 58 in jpegtran.c.

Example

  • -pixelize 640x480+0+0@4@4
    width : 640
    height : 480
    position : (0,0)
    pixelized block width : (MCU x 4)
    pixelized block height : (MCU x 4)
    Align mode : off
  • -pixelize 320x240+192+256@1@2
    width : 320
    height : 240
    position : (192,256)
    pixelized block width : (MCU x 1)
    pixelized block height : (MCU x 2)
    Align mode : on
  • -pixelize 512x384-64-48@0
    width : 512
    height : 384
    position : (64,48) (from lower right corner)
    pixelized block width : block
    pixelized block height : block
    Align mode : don't care
  • -pixelize 640x480+0+0@4@4 -pixelize 640x480+0+480@8@8
    2 parts for pixelization area are specified.

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Lossless pixelization extension for Jpegtran

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