Convert a true color image to a palette image in PHP

<?php//from  w ww . ja v  a  2s  .  co m
// Create a new true color image
$im = imagecreatetruecolor(100, 100);

// Convert to palette-based with no dithering and 255 colors
imagetruecolortopalette($im, false, 255);

// Save the image
imagepng($im, './test.png');
imagedestroy($im);
?>