Convert pgm to pnm

What is the difference between .pgm and .pnm?

Description: A PGM file is a grayscale image file saved in the portable gray map (PGM) format and encoded with one or two bytes (8 or 16 bits) per pixel. It contains header information and a grid of numbers that represent different shades of gray from black (0) to white (up to 65,536). PGM files are typically stored in ASCII text format, but also have a binary representation.; The PNM (Portable Any Map Image) file format is a subset of the broader Netpbm format, designed for storing various types of digital images. It acts as an umbrella term for three specific types of grayscale, color, and black-and-white images, represented by PBM (Portable Bitmap), PGM (Portable Graymap), and PPM (Portable Pixmap) formats respectively. PNM files are known for their simplicity and ease of conversion to other image formats.