Use of a Local Color Map is optional. It is defined here for future use. If the “M” bit of byte 10 of the Image Descriptor is set to “1”, then a color map is placed after the Image Descriptor. It applies only to the following image. At the end of the image, the color map will revert to that defined after the Screen Descriptor. Note that the “pixel” field of byte 10 of the Image Descriptor is used only if a Local Color Map is indicated. This defines the parameters not only for the image pixel size, but determines the number of color map entries that follow. The bits-per-pixel value will also revert to the value specified in the Screen Descriptor when processing of the following image is complete.