fstopgm

Convert the specified Usenix FaceSaver file into a PGM image

$ fstopgm [path/to/input.fs] > [path/to/output.pgm]

fstopgm [fstopfile]

fstopgm is a specialized command-line utility from the Netpbm toolkit. Its primary function is to convert image files in the Sun FrameStore (FST) format into the Portable Graymap (PGM) format.

The FST format is a proprietary image format historically associated with Sun Microsystems workstations and their FrameStore image database system. PGM is a simple, common grayscale image format part of the Netpbm family, widely used for basic image manipulation and processing due to its straightforward structure.

This tool is essential for users needing to process or view old Sun FrameStore images using modern image tools or for integration into standard image processing workflows that leverage Netpbm's interoperability. It typically reads the FST image from a specified file or standard input and writes the resulting PGM data to standard output, making it suitable for use in Unix pipelines.

fstopgm is part of the Netpbm package; it must be installed for fstopgm to be available.
The Sun FrameStore (FST) format is relatively obscure today, primarily used on older Sun systems.
Conversion to PGM implies a grayscale output. Any color information present in the original FST file (if the format supports it, though FST is often grayscale) will be lost or converted to intensity values.
Output is written to standard output by default, which can be redirected to a file.

fstopgm follows the Unix convention of reading from standard input if no fstopfile is specified, and writing the resulting PGM image to standard output. This design makes it highly suitable for use in command-line pipelines. For instance, an fstop file can be piped directly into fstopgm, or its output can be piped to another Netpbm utility for further processing.

fstopgm is a component of the Netpbm project, an extensive toolkit for graphic file conversion that originated from Jef Poskanzer's Pbmplus package in the late 1980s and early 1990s.

Netpbm commands, including fstopgm, are designed to adhere to the Unix philosophy of small, specialized tools that do one thing well and can be easily combined using pipes. The utility reflects the historical need to convert between various image formats prevalent in different computing environments, particularly as Sun Microsystems workstations were common during the period of Netpbm's initial development.

pgm(5), fstop(5), pnmtofstop(1), netpbm(1)