Transformation tools change the position or geometry of an image or part of an image. These tools do not alter the colors or the transparency of pixels, although, in some cases, regions of the image are left vacant and new pixel values must be determined. For example, if a section of an image is rotated, empty areas are created, which are automatically filled with the current background color. Also, when pixels are rearranged, they are usually not in exactly the same relative positions, so some pixels are lost and others must be computed.