Convert PNM to CAL

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 CAL file extension, known as CALS (Continuous Acquisition and Life-cycle Support) Type 1 Image, is a 1-bit black-and-white raster image format developed by the U.S. Department of Defense in the mid-1980s to standardize graphics data interchange for military documentation. It is primarily used for storing and sharing monochrome images while retaining orientation metadata. The format supports both uncompressed and compressed (using CCITT Group 4 compression) images.