This format is used by Olympus cameras to create RAW images. These files record data from the camera matrix that are used to generate the image. It contains raw data about contrast, saturation, color temperature, as well as metadata. The exposure and white balance can be changed in an ORF image while maintaining the level of detail and quality of the photo.
PGM is a storage format for grayscale images. Files in this format can be opened using software: ACDSee Photo Manager 14, ACD Systems Canvas 15, Corel PaintShop Pro X4. This type of file can be edited with a text editor. PGM files can be in two versions: P2 / P5. P2 are readable, P5 - to binary formats.