PHP Snippets
image_inverse
Information
(PHP Version >= 4.0.6)Functions used in this snippet: imagesx, imagesy, imagecreatetruecolor, imagecolorat, imagesetpixel, imagecolorallocate.
Description
int image_inverse( int img )
Makes the image img have all of its colors inversed.
*Note: This is a fairly slow function so it would be best to do it once and save the file for multiple viewings.
Snippet
<?php
function image_inverse($img){
$x = imagesx($img);
$y = imagesy($img);
$dest = imagecreatetruecolor($x, $y);
for($i=0; $i<$x; $i++){
for($j=0; $j<$y; $j++){
$rgb = imagecolorat($img, $i, $j);
$r = ($rgb >> 16) & 0xFF;
$g = ($rgb >> 8) & 0xFF;
$b = $rgb & 0xFF;
imagesetpixel($dest, $i, $j, imagecolorallocate($dest, (255 - $r), (255 - $g), (255 - $b)));
}
}
return $dest;
}
?>
Example
image_inverse Can be used in the following way:
<?php
$img = imagecreatefromjpeg('someimage.jpg'); // create image
$img = image_inverse($img); // inverses image
header('Content-type: image/jpeg'); // send header
imagejpeg($img); // output image to browser
?>
Updated on Aug 3rd at 4 am.
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