Ticket #2805: 2805.diff

wp-admin/includes/image.php

@@ -66 +66 @@
                         }
 
                         $thumbnail = imagecreatetruecolor( $image_new_width, $image_new_height);
+
+                        // preserve PNG transparency
+                        if( $type[2] == 3 &&
+                                function_exists( 'imagealphablending' ) &&
+                                function_exists( 'imagesavealpha' )) {
+                                imagealphablending($thumbnail, false);
+                                imagesavealpha($thumbnail,true);
+                        }
+
                         @ imagecopyresampled( $thumbnail, $image, 0, 0, 0, 0, $image_new_width, $image_new_height, $image_attr[0], $image_attr[1] );
 
                         // If no filters change the filename, we'll do a default transformation.