Convert JBIG to PGM

The JBIG (Joint Bi-level Image Group) file extension, standardized as ISO/IEC 11544 and ITU-T T.82 in 1993, is a lossless image compression format primarily used for binary images, such as those in fax transmissions. Developed by the Joint Bi-level Image Experts Group, JBIG offers significant compression efficiency over previous standards, achieving up to 50% better compression than Fax Group 4. Its history dates back to 1988 when ISO and CCITT collaborated to create a unified standard for bi-level image coding.

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.