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.

See the Security Information section below.


Security information

You are strongly encouraged to upgrade to the latest version 0.7.7.

Here is a list security-sensitive issues that affect the previous versions:

  • Joonun Jang reported a buffer overflow vulnerability in the GIF decoder, discovered by a fuzzer developed by the SoftSec group at KAIST. All versions prior to 0.7.7 that support GIF files (i.e. from version 0.5 to version 0.7.6) are affected.

  • Jaeseung Choi reported an integer overflow vulnerability in the TIFF decoder. All versions prior to 0.7.7 that support TIFF files (i.e. from version 0.5.3 to version 0.7.6) are affected.

  • Henri Salo and Hans Jerry Illikainen reported two vulnerabilities in the compressed BMP decoder, discovered by using the American Fuzzy Lop. All versions prior to 0.7.6 that support compressed BMP files (i.e. from version 0.6 to version 0.7.5) are affected.

  • Gynvael Coldwind and Mateusz Jurczyk reported a use-after-free vulnerability in the palette reduction code, affecting the versions 0.7, 0.7.1 and 0.7.2, partially fixed in version 0.7.3, and fully fixed in version 0.7.4.


    OptiPNG is open-source software, released under the zlib license.
    The contributing authors, i.e. the people who contributed source code to OptiPNG.
    The program revision history and the acknowledged contributors.


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Last updated: 2017-Dec-27