Layer masks are used to remove complex and detailed objects from an image, especially if the image is going to be processed again on a later stage. Using this technique, objects, products, backgrounds and other elements (eg shadows/reflections) can be positioned on different levels. So, different levels may contain various features. For example, the processed product may be on one level, the background on another level, and the path, shading or retouching on another level, etc. Very often layer masks replace the eraser tool to correct or remove objects. Layers can only be used in conjunction with a PSD or Tiff file. When using masks during the editing process, there are multiple tools accessible to make the masking result perfect.