Should use ImageReceiver inside to get image and than do some modifications (like apply Mask for Category). Has higher priority than ImageReceiver. If it is present we should use this func. If object's image doesn't have additional modifications that should be done above original skin image - use ImageReceiver.
Gets or sets a unique tag that represents this image. The tag should be somewhat human readable as this is the value that will often be store in grid cells for this image.
