.PBM File Extension

Portable Bitmap Image

Developer Jef Poskanzer
3.8  |  14 Votes
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What is a PBM file?

A PBM file is a black-and-white image saved in the Portable Bitmap format. It consists of a plain text header and a grid of 0s and 1s that specify the color of each of the image's pixels. 0s represent white pixels; 1s represent black pixels.

More Information

Screenshot of a .pbm file in File Viewer Plus 4
PBM file open in File Viewer Plus 4

Jef Poskanzer developed the PBM format as part of his Netpbm project. PBM is an intermediate format, used primarily when converting images from one format to another. In the middle of a conversion, Netpbm may save an image as a PBM file. It then uses the PBM file to create the converted image. (Netpbm uses the .PGM and .PPM formats in similar fashion.)

Two variants of the PBM format exist. Files saved in the original PBM format, identified by the magic number P1 in their header, always contain only one image. Files saved in the more recent version of the PBM format, identified by the magic number P4 in their header, can contain more than one image. Also, P1 PBM files can contain whitespace in their raster grid; P4 files cannot.

NOTE: Each PBM image's width and height is specified in its header. For example, an image that is 50 pixels wide by 65 pixels tall will include the numbers 50 65 in its header.

How to open a PBM file

PBM file open in Microsoft Notepad
PBM file open in Microsoft Notepad

You can open a PBM file with many image viewers and editors, including XnViewMP (multiplatform), Inkscape (multiplatform), Apple Preview (Mac), or Adobe Photoshop (Windows, Mac).

You can also open a PBM file with Microsoft Notepad (Windows), Apple TextEdit (Mac), or any other text editor, to view the plain text data it contains. This can be useful if, for example, you want to make sure your PBM file is formatted correctly before you attempt to open it in an image editor.

How to convert a PBM file

You can use GIMP, Inkscape, or XnViewMP to convert PBM images to other formats. For example, XnViewMP can convert PBM files to the following formats (and many others):

  • .JPG - JPEG Image
  • .GIF - Graphical Interchange Format
  • .PNG - Portable Network Graphic
  • .TIFF - Tagged Image File Format
  • .BMP - Bitmap Image
  • .PCX - Paintbrush Bitmap Image
  • .TGA - Targa Graphic
  • .JP2 - JPEG 2000 Core Image
  • .JXR - JPEG XR Image
  • .WEBP - WebP Image

Programs that open PBM files

Included with OS

Verified by FileInfo.com

The FileInfo.com team has independently researched the Portable Bitmap Image file format and Mac, Windows, Linux, and Android apps listed on this page. Our goal is 100% accuracy and we only publish information about file types that we have verified.

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