#TITLE

Implementation of Image Denoising based on Backward Stochastic
Differential Equations


#VERSION

2.0 


#AUTHOR

Dariusz Borkowski <[email protected]>


#CONTENTS

./BSDE.cpp - This program reads PNG images, runs BSDE
	 method and writes PNG images. Only 8bit (grayscale
	 and RGB) PNG images are handled. 

./libdenoising.cpp, ./libdenoising.h - Implementation of BSDE
	method: Algorithm 1, Algorithm 2, Algorithm 3.
	This source code provides an implementation of the BSDE
	denoising algorithm.

./lib.cpp, ./lib.h - Implementation of classes dbImageRGB
	and dbImage representing RGB and greyscale images and
	operations on them.

./io_png.c, ./io_png.h - PNG read/write interface by Nicolas
	Limare <[email protected]>.

./lena.png, ./dice.png, ./traffic.png, ./computer.png,
	./book.png, book10.png - Test PNG images.



The code is written in C/C++ and should compile on any system
with an g++ compiler.

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

The implementation uses OPENMP which not supported by old
versions of g++. 


Ubuntu 22.04 LTS installation:

sudo apt-get install make
sudo apt-get install g++
sudo apt-get install libpng-dev


# COMPILATION INSTRUCTIONS

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


# USAGE

usage: ./BSDE original.png sigma noisy.png denoised.png add_noise c 

BSDE takes 6 parameter: 
* original.png 		: initial noise free image (PNG image)
* sigma     		: the noise standard deviation
				(non negative real number)
* noisy.png  		: noisy image used by the denoising
				algorithm (PNG image)
* denoised.png	 	: denoised image (PNG image)
* add_noise     	: the add noise option (integer number
				from the set {0,1}) 
* c			: the enhancing parameter c (non-negative
				real number from the range [0, 1])


# EXAMPLES OF USE

Use the provided makefile, with the command `make tests`

Example 1.
We add noise with a standard deviation sigma=20 to lena.png original
image and reconstruct it without the enhancing effect c=0.0. We save
the noisy and reconstructed image as in.png and out.png, respectively.
The program displays the PSNR value of the original and reconstructed
image.

./BSDE lena.png 20 in.png out.png 1 0.0


Example 2.
We reconstruct lena.png noisy image with a sigma=10 and the enhancing
effect c=0.4. We save the noisy and reconstructed image as in.png and
out.png, respectively. In this case, we omit the display of the PSNR
value.

./BSDE lena.png 10 in.png out.png 0 0.4


# COPYRIGHT AND LICENSE INFORMATION

Copyright (c) 2023 Dariusz Borkowski

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
License for more details.
 
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.