spriter('*.png', 'hires.png', 0);

< ?php
		function spriter($dir = '*.png', $dest = 'sprite.png', $spacing = 0) {

			// define icons sizes
			$icon_width = 32;
			$icon_height = 32;

			// start height of my sprite canvas
			$height = 0;

			// select all the icons and read theri height to build our canvas size.
			foreach (glob($dir) as $file) {
				list($w, $h) = getimagesize($file);
				// make sure out icon is a 32px sq icon
				if ($h == $icon_height)
					$height += ($h + $spacing);
			}

			// double our canvas height to allow for a gray-scale versions.
			$height = ($height * 2);

			// create our canvas
			$img = imagecreatetruecolor($icon_width, $height);
			$background = imagecolorallocatealpha($img, 255, 255, 255, 127);
			imagefill($img, 0, 0, $background);
			imagealphablending($img, false);
			imagesavealpha($img, true);

			// start placing our icons from the top down.
			$pos = 0;
			foreach (glob($dir) as $file) {
				$tmp = imagecreatefrompng($file);
				if (imagesy($tmp) == $icon_height) {
					imagecopy($img, $tmp, 0, $pos, 0, 0, $icon_width, $icon_height);
					$pos += ($icon_height + $spacing);
				}
				imagedestroy($tmp);
			}

			// place all of our icons on again, but this time convert them to gray-scale
			foreach (glob($dir) as $file) {
				$tmp = imagecreatefrompng($file);
				if (imagesy($tmp) == $icon_height) {
					imagefilter($tmp, IMG_FILTER_GRAYSCALE);
					imagecopy($img, $tmp, 0, $pos, 0, 0, $icon_width, $icon_height);
					$pos +=  ($icon_height + $spacing);
				}
				imagedestroy($tmp);
			}

			// create our final output image.
			imagepng($img, $dest);
		}