histogram equalization

<?php
  //*********************************
  // FILENAME     : class.gambar.php
  // PURPOSE      : generate histogram equalization from given image
  // CREATED BY   : Cahya DSN
  // CREATED DATE : 2012/12/06
  // UPDATE DATE  : 2012/12/07
  // DOWNLOAD     : http://adzan.16mb.com/source/histogram.zip
  //*********************************

class gambar{
  private $filename;
  private $img;
  private $reds = array();
  private $blues = array();
  private $greens = array();
  private $values = array();
  private $freqr = array();
  private $freqb = array();
  private $freqg = array();
  private $width,$height,$totalpixels;
  private $fr,$fg,$fb,$fv;

  public function __construct($filename)
  {
    $this->filename=$filename;
    $info = getimagesize($filename);
    $this->width = $info[0];
    $this->height = $info[1];
    $this->totalpixels = $this->width * $this->height;
    $this->img = imagecreatefromjpeg($filename);
    for($i=0;$i<256;$i++){
      $this->reds[$i]=0;
      $this->blues[$i] =0;
      $this->greens[$i]=0;
      $this->values[$i]=0;
      $this->freqr[$i]=0;
      $this->freqb[$i]=0;
      $this->freqg[$i]=0;
    }
  }
  //Build image histogram
  public function build_histogram()
  {
    for ($i = 0; $i < $this->height; $i++) {
      for ($j = 0; $j < $this->width; $j++) {
        $rgb = imagecolorat($this->img, $j, $i);
        $r = ($rgb >> 16) & 0xFF;
        $g = ($rgb >> 8) & 0xFF;
        $b = $rgb & 0xFF;
        $v = round(($r + $g + $b) / 3);
        // Add counts to our histogram arrays for each color.
        $this->reds[$r]++;
        $this->greens[$g]++;
        $this->blues[$b]++;
        $this->values[$v]++;
      }
    }
    // Sort them by keys into order
    ksort($this->reds);
    ksort($this->greens);
    ksort($this->blues);
    ksort($this->values);
  }
  // Build frequency charts for all colors (cummulative distribution function)
  public function build_cdf()
  {
    $this->fr=0;
    $this->fg=0;
    $this->fb=0;
    $this->fv=0;
    // Loop through all values and sum counts from 0 to current column $i
    for ($i = 0; $i <= 255; $i++) {
      $sumR = 0;
      $sumG = 0;
      $sumB = 0;
      $sumV = 0;
      for ($j = 0; $j <= $i; $j++) {
        // Sums for Red, Green, Blue
        $sumR += $this->reds[$j];
        $sumG += $this->greens[$j];
        $sumB += $this->blues[$j];
        $sumV += $this->values[$j];
      }
      // Stash sums into frequency charts for each color
      $this->freqr[$i] = $sumR;
      $this->freqg[$i] = $sumG;
      $this->freqb[$i] = $sumB;
      $this->freqv[$i] = $sumV;
      $this->fr=($this->fr==0 && $this->freqr[$i]!=0)?$this->freqr[$i]:$this->fr;
      $this->fg=($this->fg==0 && $this->freqg[$i]!=0)?$this->freqg[$i]:$this->fg;
      $this->fb=($this->fb==0 && $this->freqb[$i]!=0)?$this->freqb[$i]:$this->fb;
      $this->fv=($this->fv==0 && $this->freqv[$i]!=0)?$this->freqv[$i]:$this->fv;
    }
  }

  public function grayscale()
  {
    $newimg = @imagecreatetruecolor($this->width, $this->height);
    $color = imagecolorallocate($newimg, 255, 255, 255);
    for ($i = 0; $i < $this->height; $i++) {
      for ($j = 0; $j < $this->width; $j++) {
        $rgb = imagecolorat($this->img, $j, $i);
        $r = ($rgb >> 16) & 0xFF;
        $g = ($rgb >> 8) & 0xFF;
        $b = $rgb & 0xFF;
        $v = (int)(($r+$g+$b)/3);
        $color = imagecolorallocate($newimg, $v, $v, $v);
        imagesetpixel($newimg, $j, $i, $color);
      }
    }
    header('Content-Type: image/jpg');
    imagejpeg($newimg, NULL, 100);
    imagedestroy($newimg);
  }

  public function red()
  {
    $newimg = @imagecreatetruecolor($this->width, $this->height);
    $color = imagecolorallocate($newimg, 255, 255, 255);
    for ($i = 0; $i < $this->height; $i++) {
      for ($j = 0; $j < $this->width; $j++) {
        $rgb = imagecolorat($this->img, $j, $i);
        $r = ($rgb >> 16) & 0xFF;
        $color = imagecolorallocate($newimg, $r, 0, 0);
        imagesetpixel($newimg, $j, $i, $color);
      }
    }
    header('Content-Type: image/jpg');
    imagejpeg($newimg, NULL, 100);
    imagedestroy($newimg);
  }

  public function green()
  {
    $newimg = @imagecreatetruecolor($this->width, $this->height);
    $color = imagecolorallocate($newimg, 255, 255, 255);
    for ($i = 0; $i < $this->height; $i++) {
      for ($j = 0; $j < $this->width; $j++) {
        $rgb = imagecolorat($this->img, $j, $i);
        $g = ($rgb >> 8) & 0xFF;
        $color = imagecolorallocate($newimg, 0,$g, 0);
        imagesetpixel($newimg, $j, $i, $color);
      }
    }
    header('Content-Type: image/jpg');
    imagejpeg($newimg, NULL, 100);
    imagedestroy($newimg);
  }

  public function blue()
  {
    $newimg = @imagecreatetruecolor($this->width, $this->height);
    $color = imagecolorallocate($newimg, 255, 255, 255);
    for ($i = 0; $i < $this->height; $i++) {
      for ($j = 0; $j < $this->width; $j++) {
        $rgb = imagecolorat($this->img, $j, $i);
        $b = $rgb & 0xFF;
        $color = imagecolorallocate($newimg, 0, 0, $b);
        imagesetpixel($newimg, $j, $i, $color);
      }
    }
    header('Content-Type: image/jpg');
    imagejpeg($newimg, NULL, 100);
    imagedestroy($newimg);
  }

  public function output()
  {
    $newimg = @imagecreatetruecolor($this->width, $this->height);
    $color = imagecolorallocate($newimg, 255, 255, 255);
    for ($i = 0; $i < $this->height; $i++) {
      for ($j = 0; $j < $this->width; $j++) {
        $rgb = imagecolorat($this->img, $j, $i);
        $r = ($rgb >> 16) & 0xFF;
        $g = ($rgb >> 8) & 0xFF;
        $b = $rgb & 0xFF;
        $v = (int)(($r+$g+$b)/3);
        $adjR = (int)((float)abs($this->freqr[$r]-$this->fr) * (float)(255.0 / (float)($this->totalpixels-$this->fr)));
        $adjG = (int)((float)abs($this->freqg[$g]-$this->fg) * (float)(255.0 / (float)($this->totalpixels-$this->fg)));
        $adjB = (int)((float)abs($this->freqb[$b]-$this->fb) * (float)(255.0 / (float)($this->totalpixels-$this->fb)));
        $color = imagecolorallocate($newimg, $adjR, $adjG, $adjB);
        imagesetpixel($newimg, $j, $i, $color);
      }
    }
    header('Content-Type: image/jpg');
    imagejpeg($newimg, NULL, 100);
    imagedestroy($newimg);
  }

}
/*********** example *************
$histo=new gambar("contoh.jpg");
$histo->build_histogram();
$histo->build_cdf();
$histo->output();
*******************************/
//all used files and examples can be download @ http://adzan.16mb.com/source/histogram.zip
?>