Image format
The PPM format
PPM is a bare-bones color image format with no compression. PPM comes from Jef Poskanzer’s Netpbm toolkit (1988), designed so programs could swap images with almost no code.
When to use PPM
Use PPM when code you are writing, or a research tool, wants raw RGB pixels with a tiny header.
It is best for feeding images into scripts, research code and command-line pipelines, and it opens on GIMP, ImageMagick, scientific and command-line tools — not browsers or phones.
How to open it: GIMP, ImageMagick, IrfanView and macOS Preview open PPM files.
| Full name | Portable Pixmap |
|---|---|
| Extensions | .ppm, .pnm |
| MIME type | image/x-portable-pixmap |
| Introduced | 1988 |
| Compression | Uncompressed |
| Transparency | No |
| Animation | No |
| Support | Specialist format |
| Typical size | Width × height × 3 bytes, plus a few bytes of header |
Good at
- So simple a program can write one in a few lines
- No compression to decode
Not so good at
- Huge files
- Almost no everyday software opens it
The common mistake
PPM files come in a text form and a binary form; text PPMs are several times larger again and some tools only read one of the two.
Questions
What is a PPM file?
PPM (Portable Pixmap) is a bare-bones color image format with no compression. PPM comes from Jef Poskanzer’s Netpbm toolkit (1988), designed so programs could swap images with almost no code.
How do I open a PPM file?
GIMP, ImageMagick, IrfanView and macOS Preview open PPM files.
How do I make a PPM file?
Open the Image Converter, drop your file and choose PPM. It converts in your browser, so nothing is uploaded.