This file format is used as a canvas (background) in a variety of image editing software in order to set the main color of the image. It is used to fill the canvas with one solid color. It belongs to the group of 'pseudo-image' file formats. It can be used for the fill color, which is chosen from the selected area in a particular image.
A bitmap image in the Portable Any Map format that was originally developed for processing and storing several types of monochrome and color images without compression as well as grayscale images. Bitmap graphics data in a PNM file are stored using ASCII or binary structure.