Why won't my PNM file display in the browser?

No browser supports it — browsers render PNG, JPEG, GIF, WebP, AVIF, SVG and BMP, and nothing else. The file downloads instead and needs an image editor.

What's the difference between PBM, PGM, PPM and PNM?

PBM is bilevel black and white, PGM is greyscale, PPM is full colour. PNM is the umbrella name covering all three.

Should I convert PNM to PNG?

For anything anyone needs to look at, yes — PNG is lossless, displays in every browser, and is almost always smaller. Keep the original only if a specific tool requires it.

Host a PNM file and share it as a link

Put a Netpbm image online at its own address — the deliberately simple formats used in image processing pipelines.

You can host:

Drop your PNM file here

Any other file works too — up to 25.0 MB, or 100.0 MB for a whole site

Free to use. Your PNM file is live at your-name.99helpers.site in about ten seconds.

What is a .pnm file?

The Netpbm family — PBM for black and white, PGM for greyscale, PPM for colour, and PNM covering all three — stores images in the simplest possible way: a short text header followed by raw pixel values. They exist to be trivially easy to read and write, which is why image processing research and Unix pipelines use them.

What people use PNM files for

Intermediate files in image processing pipelines
Computer vision and academic research
Test images with a known, simple structure
Output from scientific instruments

What opens a PNM file

GIMP, ImageMagick and Netpbm tools
Every image processing library
Any text editor, for the ASCII variants
No browser displays PNM

How to host a PNM file

1
Drop your PNM file in
Drag it onto the box at the top of this page, or click to choose it. Files up to 25 MB are supported, and nothing is uploaded until you publish.
2
Pick an address
Type a name and we'll tell you straight away whether it's free. That becomes the link: test-image.99helpers.site
3
Publish and share
Create a free account — that step exists so the file is yours to update, replace or delete — and the link is live within seconds.

The same three steps work for any file — see how file hosting works on 99helpers.com.

What happens when someone opens the link

The file downloads. Browsers don't support Netpbm formats, though the ASCII variants are readable in a text editor.

Why host a PNM file instead of emailing it?

Research and pipeline intermediates get passed between collaborators, and these files are simple enough that hosting one is a reasonable way to share a test case.

Worth knowing before you publish

Uncompressed, so files are large relative to what they contain — convert to PNG for sharing.
The ASCII variants are literally readable as text, which is occasionally useful for debugging.
ImageMagick converts the whole family in one command.

PNM hosting questions

Why won't my PNM file display in the browser?: No browser supports it — browsers render PNG, JPEG, GIF, WebP, AVIF, SVG and BMP, and nothing else. The file downloads instead and needs an image editor.
What's the difference between PBM, PGM, PPM and PNM?: PBM is bilevel black and white, PGM is greyscale, PPM is full colour. PNM is the umbrella name covering all three.
Should I convert PNM to PNG?: For anything anyone needs to look at, yes — PNG is lossless, displays in every browser, and is almost always smaller. Keep the original only if a specific tool requires it.

Put your PNM file online now

It takes about ten seconds, and you only make an account once the file is ready to go live.

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Hosting guides for related formats

Host a PNG image Host a BMP image Host a TIFF image Host a Portable Float Map (PFM)Host an OpenEXR image Host an AAI Dune image

PNM is one of over 211 formats you can host — see free file hosting for any file type for the full list, or read the hosting guides for other file types.