Index: core/units/helpers/image_helper.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/units/helpers/image_helper.php	(revision 15698)
+++ core/units/helpers/image_helper.php	(revision )
@@ -64,7 +64,12 @@
 				} elseif (preg_match('/default:(.*)/', $format_part, $regs)) {
 					$res['default'] = FULL_PATH.THEMES_PATH.'/'.$regs[1];
 				}
+				elseif ( preg_match('/^filter:(.*)$/', $format_part, $regs) ) {
+					$format_part_params = explode('|', $regs[1]);
+					$res['filter_type'] = array_shift($format_part_params);
+					$res['filter_params'] = $format_part_params;
-			}
+				}
+			}
 
 			return $res;
 		}
@@ -111,7 +116,7 @@
 				}
 
 				$src_path = dirname($src_image);
-				$transform_keys = Array ('crop_x', 'crop_y', 'fill', 'wm_filename');
+				$transform_keys = Array ('crop_x', 'crop_y', 'fill', 'wm_filename', 'filter_type');
 
 				if ($needs_resize || array_intersect(array_keys($params), $transform_keys)) {
 					// resize required OR watermarking required -> change resulting image name !
@@ -218,6 +223,9 @@
 						return @$write_function($dst_image_rs, $params['dst_image']);
 					}
 
+					// 4. apply filter
+					$this->applyFilter($dst_image_rs, $params);
+
 					return @$write_function($dst_image_rs, $params['dst_image'], $write_function == 'imagepng' ? 0 : 100);
 				}
 			}
@@ -408,6 +416,36 @@
 			imagecopy($src_image_rs, $watermark_img_rs, $x_position, $y_position, 0, 0, $watermark_width, $watermark_height);
 
 			return $src_image_rs;
+		}
+
+		/**
+		 * Applies filter to an image.
+		 *
+		 * @param resource $src_image_rs Source image.
+		 * @param array $params Parameters.
+		 *
+		 * @return boolean
+		 * @access protected
+		 * @throws InvalidArgumentException When unknown filter type given.
+		 * @link   http://php.net/manual/en/function.imagefilter.php
+		 */
+		protected function applyFilter(&$src_image_rs, array $params)
+		{
+			if ( !array_key_exists('filter_type', $params) ) {
+				return true;
+			}
+
+			$filter_type = strtoupper($params['filter_type']);
+			$filter_params = (array)$params['filter_params'];
+
+			if ( !defined('IMG_FILTER_' . $filter_type) ) {
+				throw new InvalidArgumentException(sprintf('Unknown filter type "%s"', $filter_type));
+			}
+
+			array_unshift($filter_params, constant('IMG_FILTER_' . $filter_type));
+			array_unshift($filter_params, $src_image_rs);
+
+			return call_user_func_array('imagefilter', $filter_params);
 		}
 
 		/**
\ No newline at end of file