PCX is standard presentation graphics developed by ZSoft Korporation. Used graphics program ZSoft PC Paintbrush for MS-DOS, word processing and desktop publishing applications, such as Microsoft Word and Ventura Publisher. Not as popular analog BMP, although supported by specific graphics editors such as Adobe Photoshop, Corel Draw, GIMP and others.
PBM is a Portable image in black and white. Can be opened with programs: Adobe Photoshop CS, ACD Systems Canvas 15, ACD Systems ACDSee 17, Newera Graphics Converter Pro, Corel PaintShop Pro X6. File contains 1 bit per pixel. PBM is a kind of file format PPM. And can be readable or binary.