How to Convert a PPM File. A PPM file extension indicates that the file is a Portable Pixmap image file. The PPM file is a type of bitmap file format. However, the PPM file type is an uncompressed ...

This is not a valid bitmap file, or its format is not currently supported. However, the same files can be opened using apps like GIMP, Photoshop, Paint 3D, IrfanView, Paint.net, etc.