_image_imagemagick_convert is stripping '#' off of color codes, causing them to fail.

I've been trying to figure out why my calls to image_rotate() have been failing with the following message:

ImageMagick reported an error: convert: unrecognized color `000000' @ warning/color.c/GetColorCompliance/948. .

I started inserting drupal_set_messages() here and there to test things out and I eventually found that _image_imagemagick_convert() is stripping the hash off the color codes:

function _image_imagemagick_convert($source, $dest, $args) {
  $command = implode(' ', array(
    preg_replace("/[^A-Za-z0-9\!\.\-\+\_\/\040]/", '', implode(' ', $args)),
    escapeshellarg($source),
    escapeshellarg($dest),
  ));

  drupal_set_message("MHEINZ: " . print_r($command,1));
  if (0 != _image_imagemagick_convert_exec($command, $output, $errors)) {
    return FALSE;
  }
  return file_exists($dest);
}

Generates

MHEINZ: -rotate 270 -background 000000 -quality 75 -density 72 -units PixelsPerInch 'sites/mwheinz.no-ip.info/files/images/DreamNeedles.JPG' '/private/tmp/acidfreeqP3ngB.jpg'

This problem only affects rotate because it appears to be the only function that passes a color to ImageMagick.

Unfortunately, simply adding '#' to the preg_replace() also causes problems - because it gets interpreted as the beginning of a comment when the command is executed, so the complete patch has to be slightly more complex. The final patch looks like this:

--- image.imagemagick.orig      2011-02-23 12:27:06.000000000 -0500
+++ image.imagemagick.inc       2011-02-23 12:30:37.000000000 -0500
@@ -105,7 +105,7 @@
 function image_imagemagick_rotate($source, $dest, $degrees, $bg_color = 0x000000) {
   $args = array(
     'rotate' => '-rotate ' . (float) $degrees,
-    'background' => '-background #' . str_pad(dechex($bg_color), 6, 0),
+    'background' => '-background "#' . str_pad(dechex($bg_color), 6, 0) . '"',
   );
   $args = _image_imagemagick_alter_invoke('rotate', $source, $args);
   return _image_imagemagick_convert($source, $dest, $args);
@@ -125,7 +125,7 @@
  */
 function _image_imagemagick_convert($source, $dest, $args) {
   $command = implode(' ', array(
-    preg_replace("/[^A-Za-z0-9\!\.\-\+\_\/\040]/", '', implode(' ', $args)),
+    preg_replace('/[^#"A-Za-z0-9\!\.\-\+\_\/\040]/', '', implode(' ', $args)),
     escapeshellarg($source),
     escapeshellarg($dest),
   ));