Reference

PGM

PGM (Portable Graymap) is the grayscale member of the Netpbm family. It stores an image as gray levels per pixel in a simple, easy-to-parse layout, making it a common intermediate format in image processing.

Files & formatsGeneral

PGM

Also known as: Portable Graymap, .pgm file, Netpbm grayscale

Netpbm grayscale image format
One gray value per pixel, 8- or 16-bit
Common in computer vision and scripting

How PGM works

PGM records a single gray value per pixel, typically 8-bit (0–255) or 16-bit for finer tones. Like its siblings it has a readable ASCII form and a compact binary form.

It sits between PBM (pure black and white) and PPM (full color) in the Netpbm trio, and is widely used in computer vision and scientific imaging.

Using PGM files

PGM is an uncompressed working format, so files can be large. Netpbm tools and most editors open it; convert to PNG for a smaller, shareable grayscale image.

Related terms

Keep reading the reference.

Files & formatsPBMPBM (Portable Bitmap) is the black-and-white member of the Netpbm family. It stores a 1-bit image — each pixel is simply on or off — in a deliberately simple format that is easy for programs to read and write.General Files & formatsPPMPPM (Portable Pixmap) is the full-color member of the Netpbm family. It stores red, green, and blue values per pixel in a simple, uncompressed layout, making it a handy intermediate format in image-processing pipelines.General Files & formatsPNGPNG (.png) is a lossless image format that keeps every pixel exact and supports transparency. That makes it ideal for screenshots, logos, and graphics, but files are much larger than JPEG or WebP — so a folder full of PNG screenshots can quietly fill storage.General