Local Color Correction


% Local Color Correction


* Author    : Juan Gabriel Gomila Salas <joan-by@hotmail.com>
* Copyright : (C) 2011 IPOL Image Processing On Line http://www.ipol.im/
* Licence

- 'localcolorcorrection.c' may be linked to the US Patent 6,822,762,
(November 23, 2004), Local Color Correction, by N. Moroney, R.G. Beausoleil 
and I. Sobel. 
It is provided for scientific and education only.

- All the other files are distributed under the terms of the
  GPLv3 license.

- Read/write operations (png format) make use of io_png.c and io_png.h, 
by Nicolas Limare <nicolas.limare@cmla.ens-cachan.fr>
- Conversion operations between color spaces, make use colorspace library, 
by Pascal Getreuer <getreuer@gmail.com>

This source code provides the implementation of the "local color
correction" algorithm as described in IPOL

This program reads and writes PNG images, but can be easily
adapted to any other file format.

Only 8bit RGB PNG images are handled. 


The code is written in ANSI C, and should compile on any system with
an ANSI C compiler.

The libpng and header and the libpng and zlib libraries are required
on the system for compilation and execution. See


Simply use the provided makefile, with the command `make`.


'localcolorcorrection' takes 2 mandatory parameters and 2 optional parameters: 

localcolorcorrection input.png output.png [radius=40] [option=1]

* 'input'      : input image
* 'output'     : output image
* 'radius'     : radius of the gaussian kernel used to blur the input image
* 'option'     : color management option
                 1, independent processing of RGB channels
                 2, (use HSI color space) processing of intensity channel (I=(R+G+B)/3), 
                    preserving chroma (H, S) values 
                    (equivalent to preserving original R/G/B ratios)
                 3, (use YPbPr color space) processing of luma channel, preserving
                    original chroma (Pb, Pr) values
                 4, (use HSL color space) processing of lightness channel, preserving
                    original chroma (H, S) values


Copyright 2011 IPOL Image Processing On Line http://www.ipol.im/
Author: Juan Gabriel Gomila Salas (joan-by@hotmail.com)

Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.  This file is offered as-is,
without any warranty.

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