I'm trying to make a PHP script that increases the blue value of each pixel in an image by 1.
It's important that the script goes pixel by pixel.
For some reason, however, it outputs an image that is one solid color; a brownish red block.
Why isn't this script only slightly increasing the values?? ??? ???
<?php
$img = imagecreatefromgif('logo.gif');
// get height and width
$h=imagesy($img);
$w=imagesx($img);
//display image
echo "<img src='out.gif' />";
//cycle through every pixel and add 1 to the blue value of the pixel's rgb value
$y=1;
while($y < $h) {
$x=1;
while($x < $w) {
$rgb = imagecolorat($img, $x, $y);
$red = ($rgb >> 16) & 0xFF;
$green = ($rgb >> 8) & 0xFF;
$blue = $rgb & 0xFF;
$blue++;
//define the new color and assign it to the pixel
//this is where things go wrong
$color = imagecolorallocate($img, $red, $green, $blue);
imagesetpixel($img, $x, $y, $color);
$x++;
}
$y++;
}
echo imagegif($img, 'out.gif');
?>
I know the problem is in these two lines by the way.
$color = imagecolorallocate($img, $red, $green, $blue);
imagesetpixel($img, $x, $y, $color);
