BITWISE PHP GRADIENTS

These pages use a bitwise operator to produce gradients. It comes from C language, based on binary numbers, and works only in true color images (png or jpeg). For more information on bitwise operators and php see the manual at PHP.net.
The above gradients were created with the following PHP script. The script comes from Rasmus Lerdorf, the creator of PHP, and can be seen on his site. PDF file
<?
$im = ImageCreateTrueColor(256,120);
for($x=0; $x<256; $x++) {
Imageline($im, $x, 0, $x, 40, $x*1);
Imageline($im, 255-$x, 40, 256-$x, 80, $x<<8);
Imageline($im, $x, 80, $x, 120, $x<<16);
}
Header('Content-Type: image/png');
ImagePNG($im);
?>
The gradients can be mirrored for a round gradient effect.
The Code for the above gradients is as follows.
<?
$im = ImageCreateTrueColor(256,120);
for($x=0; $x<256; $x++) {
ImageLine($im, $x/2, 0, $x/2, 40, $x*1);
ImageLine($im, 255-$x/2, 0, 255-$x/2, 40, $x*1);
ImageLine($im, $x/2, 40, $x/2, 80, $x<<8);
ImageLine($im, 255-$x/2, 40, 255-$x/2, 80, $x<<8);
ImageLine($im, $x/2, 80, $x/2, 120, $x<<16);
ImageLine($im, 255-$x/2, 80, 255-$x/2, 120, $x<<16);
}
Header('Content-Type: image/png');
ImagePNG($im);
?>
By changing the last number in the bitwise operator $x<<1, etc you will get a different line image. These can be seen with the bitwise number on this page.
You can also get some interesting effects by using ellipses and arcs. You can create backgrounds for your art work. You can also create masks.