Convert J2C to PGM

The J2C file extension stands for JPEG 2000 Code Stream, a format defined in Part 1 of the JPEG 2000 standard. Developed by the Joint Photographic Experts Group (JPEG) from 1997 to 2000, J2C files utilize wavelet-based compression, supporting both lossy and lossless compression. This format is primarily used for high-quality image storage and transmission, offering superior compression efficiency and flexibility compared to the original JPEG standard. J2C files are often embedded within other file formats like JP2 for enhanced metadata support.

The Portable Graymap (PGM) file extension, originating in the late 1980s as part of the Netpbm project, stands for "Portable Gray Map". It serves as a simple, versatile format for grayscale images, enabling easy reading and writing by various programs. Due to its straightforward structure and plain text encoding, it's often used in academic and research settings where ease of parsing and accessibility are crucial. PGM files store grayscale images in a compact, efficient manner, making them an essential tool for image processing tasks.