Convert PNM to SR

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 Sun Raster (SR) file extension, is a raster graphics file format developed by Sun Microsystems for use on their SunOS operating system. This format, which stores black-and-white, grayscale, and color bitmapped data, was widely used in UNIX-based systems and supported by various imaging applications. The Sun Raster format includes a header, an optional color map, and the bitmapped image data. Although it does not support transparency, it remains a simple and widely distributed bitmap format.