/home/edulekha/studygroup.edulekha.com/ow_libraries/wideimage/Operation/AddNoise.php
<?php
/**
* @author Tomasz Kapusta
* @copyright 2010
This file is part of WideImage.
WideImage is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
WideImage 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with WideImage; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
* @package Internal/Operations
**/
/**
* Noise filter
*
* @package Internal/Operations
*/
class WideImage_Operation_AddNoise {
/**
* Returns image with noise added
*
* @param WideImage_Image $image
* @param float $amount
* @param const $type
* @param float $threshold
* @return WideImage_Image
*/
function execute($image, $amount, $type) {
switch ($type)
{
case 'salt&pepper' : $fun = 'saltPepperNoise_fun';
break;
case 'color' : $fun = 'colorNoise_fun';
break;
default : $fun = 'monoNoise_fun';
break;
}
return self::filter($image->asTrueColor(), $fun, $amount);
}
/**
* Returns image with every pixel changed by specififed function
*
* @param WideImage_Image $image
* @param str $function
* @param int $value
* @return WideImage_Image
*/
function filter($image, $function, $value)
{
for ($y = 0; $y < $image->getHeight(); $y++)
{
for ($x = 0; $x< $image->getWidth(); $x++)
{
$rgb = imagecolorat($image->getHandle(), $x, $y);
$a = ($rgb >> 24) & 0xFF;
$r = ($rgb >> 16) & 0xFF;
$g = ($rgb >> 8) & 0xFF;
$b = $rgb & 0xFF;
self::$function($r, $g, $b, $value);
$color = imagecolorallocatealpha($image->getHandle(), $r, $g, $b, $a);
imagesetpixel($image->getHandle(), $x, $y, $color);
}
}
return $image;
}
/**
* Adds color noise by altering given R,G,B values using specififed amount
*
* @param int $r
* @param int $g
* @param int $b
* @param int $value
* @return void
*/
function colorNoise_fun(&$r, &$g, &$b, $amount)
{
$r = self::byte($r + mt_rand(0, $amount) - ($amount >> 1) );
$g = self::byte($g + mt_rand(0, $amount) - ($amount >> 1) );
$b = self::byte($b + mt_rand(0, $amount) - ($amount >> 1) );
}
/**
* Adds mono noise by altering given R,G,B values using specififed amount
*
* @param int $r
* @param int $g
* @param int $b
* @param int $value
* @return void
*/
function monoNoise_fun(&$r, &$g, &$b, $amount)
{
$rand = mt_rand(0, $amount) - ($amount >> 1);
$r = self::byte($r + $rand);
$g = self::byte($g + $rand);
$b = self::byte($b + $rand);
}
/**
* Adds salt&pepper noise by altering given R,G,B values using specififed amount
*
* @param int $r
* @param int $g
* @param int $b
* @param int $value
* @return void
*/
function saltPepperNoise_fun(&$r, &$g, &$b, $amount)
{
if (mt_rand(0, 255 - $amount) != 0) return;
$rand = mt_rand(0, 1);
switch ($rand)
{
case 0 : $r = $g = $b = 0;
break;
case 1 : $r = $g = $b = 255;
break;
}
}
/**
* Returns value within (0,255)
*
* @param int $b
* @return int
*/
function byte($b)
{
if ($b > 255) return 255;
if ($b < 0) return 0;
return (int) $b;
}
}