The Digital Agency for International Development

8 bit alpha png optimisation with pngquant

By Jay Alvarez on 28 June 2011

It looks like we may have found an alternative to great png optimisation at last, pngquant.  We really struggled with this issue on the Reaction Scorecards website as the homepage had some graphics with fine lines and alpha transparency which were proving difficult to optimise.

In the past I have used Adobe fireworks which seemed unrivalled in the open source world but pngquant is just great.

The command line tool allows you to squish the 32bit png files output from Inkscape into 8 bit files with any number of colours from 2 to 255. To make the test I used an 11.9 kB inkscape file which when processed using pngquant and 24 colours was perfectly acceptable and now had only a 3.1 kB file size. Yippee!!. I'm a happy bunny

happy transparent 8bit bunny

(MyPaint bunny 39 kB -> Gimp bunny 53 kB -> happy pngquant bunny 13 kB)