This format is used for storing bitmap images with improved levels of color and brightness performance. It combines exposures to record darker tones in the shadows or detail in the lighter areas of a given photo. HDR is able to combine multiple images with different levels of light distribution. It is used to create rich images.
PPM is a simple format for storing images portable pixmap: color (PPM), grayscale (PGM) and black and white (PBM). These formats can provide an intermediate representation of the data when converting raster image files listed three types between different platforms. PPM format was developed by Jeff Poskanzerom.