libppm - portable pixmap manipulation library.

1. About
2. Examples
3. Download
4. Changelog
5. Contact

PNM (portable anymap) is a set of simple file formats designed to represent raster images. PNM files come in three flavors:

• PBM (portable bitmap) - represents black-and-white images
• PGM (portable graymap) - represents grayscale images
• PPM (portable pixmap) - represents color images

All these files can have two formats - plain (ASCII) and raw (binary):

• P1 - plain PBM
• P2 - piain PGM
• P3 - plain PPM
• P4 - raw PBM
• P5 - raw PGM
• P6 - raw PPM

PNM images can be manipulated using netpbm package.

libppm is a lightweight, P6-type image manipulation C library than can handle both 24-bit (standard) and 48-bit (extended) RGB images. It provides basic operations on pixmaps:

• creating with given size and depth
• loading from file or stdio stream
• saving to file or stdio stream
• reading and changing subpixel values

It's advantages include:

• is designed with simplicity in mind
• is extremely lightweight
• is portable (should run on any POSIX-complaint system)
• runs on big-endian and little-endian machines
• handles both 24-bit and 48-bit pixmaps
• handles comments within pixmaps

However, it lacks:

• handling plain PPM images (as this format is very rarely used)
• handling more than one image in a PPM file

If you need these features, consider using more advanced libnetpbm.

Attached are three example programs that show how to use this library:

• normalize - normalize image (transform it to span full range of colors)
  • reads image
  • performs calculations on it's pixmap data using two different access methods
  • writes image
• heart - draw different hearts
  • creates ppm image
  • draws it
  • writes image
• histogram - generate RGB histogram
  • reads image
  • analyzes pixmap
  • creates second image
  • draws it
  • saves it

normalize code can be tested on those 24- and 48-bit files:

It should produce 24- and 48-bit ppm files equal to those:

heart can be used to generate different looking hearts. Examples:

histogram analyzes input image and draws it's RGB histogram. Example:

Download snapshot: libppm-20090622.tar.gz (md5)
Snapshots are generated daily at 07:00 CET. They require C compiler (possibly gcc), binutils, make, libtool and libc. heart requires libm.

Subversion access: http://svn.chmurka.net/libppm/trunk/libppm/
SVN version in addition to snapshot requirements requires autoconf and automake.

Changelog: changelog.php (rss)

Contact: gophi (at) chmurka.net