Desaturate not working in image styles I have an image style which has Desaturate and Scale &amp; Crop turned on.

I call it using this:

&lt;a href="&lt;?php print image_style_url('gallery_full', $image['uri']); ?&gt;"&gt;&lt;img src="&lt;?php print image_style_url('gallery_thumb_grey', $image['uri']); ?&gt;" /&gt;&lt;/a&gt;


It outputs the image resized but doesn't desaturate it. There are no errors.

Any ideas?
This is kind of a crappy answer, but the fix was to switch to using ImageMagick. I still don't know what was wrong with GD.