Portable Network Graphics#Optimizing tools

OptiPNG is a free command line program, the existing PNG files by optimizing the lossless compression reduced without altering the actual image data. It can also check the integrity of PNG files, restore metadata and other raster graphics formats (BMP, GIF, TIFF, PNM ) convert to PNG.

It optimizes the Deflate compression of the IDAT blocks, which contain the actual image data by trying out various pre-filters and parameters of the compression method. It is inspired by pngcrush; other than that it optimizes However, in addition to the Deflate compression before even color model, color palettes and bit depths without the need for additional programs like the prototype as pngrewrite or additional steps would be necessary.

OptiPNG is developed in the C programming language and will be released as free software under the zlib / libpng license.

The first version ( version 0.0) was published on 10 December 2001.

It is used, among others, Google Page Speed ​​, an extension for Mozilla-based web browser for the optimization of website performance.

There is now a modified version called rOptiPng that can deal with the files from multiple directories at once recursively.

The graphical user interface is now available for PNGPress OptiPNG For Macs with OSX 10.6 (Snow Leopard) and Intel processors.

For computers running Windows (98, 2000, XP, Server 2003, Vista, 7) is the graphical user interface OptiPNG UI available that contains the command line program already.

For the freeware image editing software Paint.NET a plugin is available that enables the compressed storage.