OptiPNG: Advanced PNG Optimizer

OptiPNG is a PNG optimizer that recompresses image files to a smaller size, without losing any information. This program also converts external formats (BMP, GIF, PNM and TIFF) to optimized PNG, and performs PNG integrity checks and corrections.
If you wish to learn how PNG optimization works, or to know about other similar tools, see the PNG-Tech article A guide to PNG optimization.
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The new OptiPNG

Redesigned

It started many months ago, with a fork from the old code. Changes have been made not only at the source code level, but also (slightly) in the user interface. The user-visible changes are outlined in the HISTORY document.

Doxygenated

Browse the opnglib API.

Mercurialized

Browse the Mercurial repository of OptiPNG Hg, or fetch it using the following command:
hg clone http://optipng.hg.sourceforge.net/hgweb/optipng/optipng

Okay, I admit, version Hg is not really a version. It's a snapshot of the Mercurial repo, taken at any point in time. It will, hopefully, pass the version 1.0 mark some day, and then it will move forward.

The olde OptiPNG

Stable

The old codebase is maintained by applying bug fixes, libpng and zlib updates (if strictly necessary), and occassionally backporting patches from the development branch. There is no other new development.

Version 0.7.x is the logical continuation of the old 0.6.x line, with minimally-disruptive code changes. There will be no version 0.8. In retrospect, I wonder how did I not get bored of leading-zero version numbers sooner...

Important!

An image-altering regression has been discovered in OptiPNG version 0.7. This affects some palette-encoded grayscale images.

If you use version 0.7, please upgrade to version 0.7.1
(Many thanks to Adam Ciarciński for discovering and fixing this defect.)

Version 0.6.5 and earlier are not affected.

Download

Security information

The earliest OptiPNG version without any known vulnerability is 0.6.3. You may use that version, or a newer one, and you are encouraged to upgrade to the latest stable version 0.7.1.

The CVE-2011-3026 vulnerability, affecting the libpng versions up to 1.4.8/1.5.8, does not affect OptiPNG, because the decompression of deflate-compressed ancillary chunks, done inside libpng, is bypassed in OptiPNG.

Documentation

  • LICENSE
    OptiPNG is open-source software, released under the zlib license.
  • AUTHORS
    The contributing authors, i.e. the people who contributed code to OptiPNG.
  • HISTORY
    The program revision history.
  • THANKS!
    The author is indebted to all the people who helped the OptiPNG development.

Contributing

Related projects

[This section is being transferred to the project's Wiki.]

Roadmap

[This section is being transferred to the project's Wiki.]
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