Convert PNM to G4

The PNM (Portable Anymap) file extension, developed by Jef Poskanzer in the 1980s, stands for Portable Any Map. It is an uncompressed raster graphics format designed for portable image storage and exchange, encompassing three sub-formats: PBM (Portable Bitmap), PGM (Portable Graymap), and PPM (Portable Pixmap). PNM files store image data in plain text or binary format, ensuring easy usage across different platforms and applications. This format is widely supported by various image editing software and is valued for its simplicity and lossless compression.

The G4 file extension, standing for CCITT Group 4 Fax Image, is a specialized format used primarily for storing black-and-white facsimile (fax) images. Its origins trace back to the Consultative Committee for International Telegraphy and Telephony (CCITT), now known as the ITU-T, which developed the Group 4 standard in the 1980s to improve fax transmission efficiency over digital networks. This format employs a high compression ratio to reduce file size while maintaining image quality, making it ideal for archiving documents and transmitting faxes in professional and business environments.