Convert j2c to pgm

What is the difference between .j2c and .pgm?

Description: The JPEG 2000 Code Stream (j2c) file format is a type of image file format that is part of the JPEG 2000 family of image standards. This format is specifically designed for encoding images in a highly efficient manner, allowing for both lossless (exact reproduction) and lossy (approximate) compression. The j2c format focuses on the core coding stream of JPEG 2000 images, representing the encoded image data without additional metadata or structure.; 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.