Convert CALS to PPM

The CALS (Continuous Acquisition and Life-cycle Support) Type 1 Image file format, developed by the United States Department of Defense in the mid-1980s, is a standard for storing raster (bit-mapped) image data, typically black-and-white. It ensures efficient data interchange and retention of orientation metadata. The format supports both uncompressed and compressed (using CCITT Group 4 compression) images. This standard was part of the broader CALS initiative aimed at improving electronic publishing and data management within the federal government.

The Portable Pixmap (PPM) file extension, an image format within the Netpbm family, stores simple, uncompressed images. Introduced in the late 1980s, PPM supports RGB color and grayscale images, making it suitable for basic image processing and conversion tasks. Its plain text encoding simplifies debugging and data manipulation, although its lack of compression results in larger file sizes compared to modern formats. As such, PPM finds limited use in contemporary applications, mainly in educational and experimental settings where ease of implementation and readability are prioritized.