1 <?php
  2     /**
  3     * @author Tomasz Kapusta
  4     * @copyright 2010
  5     
  6     This file is part of WideImage.
  7         
  8         WideImage is free software; you can redistribute it and/or modify
  9     it under the terms of the GNU Lesser General Public License as published by
 10     the Free Software Foundation; either version 2.1 of the License, or
 11     (at your option) any later version.
 12         
 13     WideImage is distributed in the hope that it will be useful,
 14     but WITHOUT ANY WARRANTY; without even the implied warranty of
 15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16     GNU Lesser General Public License for more details.
 17         
 18     You should have received a copy of the GNU Lesser General Public License
 19     along with WideImage; if not, write to the Free Software
 20     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 21     
 22     * @package Internal/Operations
 23     **/
 24     
 25     /**
 26      * Noise filter
 27      * 
 28      * @package Internal/Operations
 29      */
 30     class WideImage_Operation_AddNoise {
 31         /**
 32          * Returns image with noise added
 33          *
 34          * @param WideImage_Image $image
 35          * @param float $amount
 36          * @param const $type
 37          * @param float $threshold
 38          * @return WideImage_Image
 39          */
 40                  
 41         function execute($image, $amount, $type) {
 42             
 43             switch ($type)
 44             {
 45                 case 'salt&pepper'  :   $fun = 'saltPepperNoise_fun'; 
 46                                         break;
 47                 case 'color'        :   $fun = 'colorNoise_fun';
 48                                         break;  
 49                 default             :   $fun = 'monoNoise_fun';
 50                                         break;          
 51             }
 52             
 53             return self::filter($image->asTrueColor(), $fun, $amount);          
 54         }
 55         
 56         /**
 57          * Returns image with every pixel changed by specififed function
 58          *
 59          * @param WideImage_Image $image
 60          * @param str $function
 61          * @param int $value
 62          * @return WideImage_Image
 63          */
 64         function filter($image, $function, $value)
 65         {
 66             for ($y = 0; $y < $image->getHeight(); $y++)
 67             {
 68                 for ($x = 0; $x< $image->getWidth(); $x++)
 69                 {        
 70                     $rgb = imagecolorat($image->getHandle(), $x, $y);               
 71                     
 72                     $a = ($rgb >> 24) & 0xFF;
 73                     $r = ($rgb >> 16) & 0xFF;
 74                     $g = ($rgb >> 8) & 0xFF;
 75                     $b = $rgb & 0xFF;
 76                     
 77                     
 78                     self::$function($r, $g, $b, $value);
 79                     
 80                     $color = imagecolorallocatealpha($image->getHandle(), $r, $g, $b, $a);              
 81                     imagesetpixel($image->getHandle(), $x, $y, $color); 
 82                 }
 83             }
 84             return $image;
 85         }
 86         /**
 87          * Adds color noise by altering given R,G,B values using specififed amount
 88          *
 89          * @param int $r
 90          * @param int $g
 91          * @param int $b
 92          * @param int $value         
 93          * @return void
 94          */
 95         function colorNoise_fun(&$r, &$g, &$b, $amount)
 96         {               
 97             $r = self::byte($r + mt_rand(0, $amount) - ($amount >> 1) );
 98             $g = self::byte($g + mt_rand(0, $amount) - ($amount >> 1) );
 99             $b = self::byte($b + mt_rand(0, $amount) - ($amount >> 1) );
100         }
101         /**
102          * Adds mono noise by altering given R,G,B values using specififed amount
103          *
104          * @param int $r
105          * @param int $g
106          * @param int $b
107          * @param int $value         
108          * @return void
109          */
110         function monoNoise_fun(&$r, &$g, &$b, $amount)
111         {               
112             $rand = mt_rand(0, $amount) - ($amount >> 1);
113             
114             $r = self::byte($r + $rand);
115             $g = self::byte($g + $rand);
116             $b = self::byte($b + $rand);
117         }
118         /**
119          * Adds salt&pepper noise by altering given R,G,B values using specififed amount
120          *
121          * @param int $r
122          * @param int $g
123          * @param int $b
124          * @param int $value         
125          * @return void
126          */
127         function saltPepperNoise_fun(&$r, &$g, &$b, $amount)
128         {
129             if (mt_rand(0, 255 - $amount) != 0) return;
130             
131             $rand = mt_rand(0, 1);
132             switch ($rand)
133             {
134                 case 0 :    $r = $g = $b = 0;
135                             break; 
136                 case 1 :    $r = $g = $b = 255;
137                             break; 
138             }
139         }
140         /**
141          * Returns value within (0,255)
142          *
143          * @param int $b         
144          * @return int
145          */     
146         function byte($b)
147         {
148             if ($b > 255) return 255;
149             if ($b < 0) return 0;
150             return (int) $b;
151         }
152         
153     }
154