Update Image Colors?

[Perad]

Hi,

 

I wrote the function below. It switches out one color for another. The pictures going in are css sprites with various colors and a white background.

 

So.. sprite 1 might by blue and sprite 2 might be green.

 

The function would be run twice to replace the blue + green with whatever colors were required.

 

/**
 * Changes the color of a graphic.
 * $settings = array (
 *  'icon'
 *  'new_icon'
 *  'old_color' = array
 *  'new_color' = array
 * );
*/
function updateIconColor($settings=array()) {
	// Create Image
	$image = imagecreatefrompng($settings['icon']);

	// Convert True color image to a palatte
	imagetruecolortopalette($image, false, 255);

	// Restore Alpha
	$white = imagecolorclosest($image, 255, 255, 255);
	imagecolortransparent($image, $white);

	// Find + Set color
	$index = imagecolorclosest($image, $settings['old_color'][0],$settings['old_color'][1],$settings['old_color'][2]);
	imagecolorset($image, $index, $settings['new_color'][0], $settings['new_color'][1], $settings['new_color'][2]);

	// Restore Alpha
	imageAlphaBlending($image, true);
	imageSaveAlpha($image, true);

	// Save
	imagepng($image, $settings['new_icon']); // save image as gif
	imagedestroy($image);
}

 

How could this be updated to allow some dithering (is that what it is called?) - the thing that smooths out an image to avoid pixelation around the edges?

 

Minor question.

1) Is there any reason why imagecolorexact doesn't work in this function. When I use imagecolorexact nothing happens and the picture remains the same.

[Perad]

Alternatively, tell me how to update an images color which already has this dithering on it.

[Perad]

Does anyone know an answer to this?