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Posted by comp.lang.php on 04/14/07 17:20
[php]
/**
* Class for grayscaling image
*
* @author Phil Powell
* @version 1.2.1
* @package IMAGE_CATALOG::IMAGE
*/
class ImageGrayscaleGenerator extends ImageResizeComponents {
/
*----------------------------------------------------------------------------------------------------------------------------------------------------------
This class exists due to the rather poor performance of the
imagecopymergegray() command
Borrowing code snippet from http://us3.php.net/manual/en/function.imagecopymergegray.php
first line comment
Will perform actual grayscaling of image one pixel at a time.
-----------------------------------------------------------------------------------------------------------------------------------------------------------
*/
// REMEMBER TO USE REFERENCE POINTER ONTO $image OBJECT TO ENSURE
"static" CHANGE TO OBJECT AND NOT TO INSTANCE
/**
* Constructor. Set all properties dynamically
*
* @access public
* @param resource $image (reference)
* @param resource $newImage (reference)
* @param int $image_width
* @param int $image_height
*/
function ImageGrayscaleGenerator(&$image, &$newImage, $image_width,
$image_height) { // CONSTRUCTOR
global $section;
foreach (array($section, 'newImage', "${section}_width", "$
{section}_height") as $val) $this->$val =& ${$val};
}
/**
* Make the image grayscale
*
* @access protected
*/
function makeGray() { // VOID METHOD
global $section;
for ($i = 0; $i <= 255; $i++) $colorNDX[$i] =
@imagecolorallocate($this->newImage, $i, $i, $i);
if (is_array($colorNDX) && @sizeof($colorNDX) > 0) {
for ($y = 0; $y < $this->{$section . '_height'}; $y++) {
for ($x = 0; $x < $this->{$section . '_width'}; $x++) {
$ndx = @imagecolorat($this->image, $x, $y);
$ndxColorArray = @imagecolorsforindex($this->image, $ndx);
$avg = floor(($ndxColorArray['red'] + $ndxColorArray['green'] +
$ndxColorArray['blue']) / 3);
@imagesetpixel($this->newImage, $x, $y, $colorNDX[$avg]);
}
}
}
}
}
if ($this->isSuccessful && $image && $willGrayscale) { // GRAYSCALE
IMAGE
$igg =& new ImageGrayscaleGenerator($image, $newImage,
$image_width, $image_height);
$igg->makeGray();
$igg = null;
}
[/php]
Whenever I run this class to grayscale an image, I wind up with the
resulting image being horribly mangled to the point of its original
format completely irreparable, furthermore, I wind up with an Apache
segfault and having to reboot the server to correct the problem.
Um, why?
Phil
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