PNG Compression

Today I had a set of fairly sizable PNGs to compress, viagra sale and I decided that now would be as good a time as any to benchmark a few of the PNG compression tools available out there.

The files I used were a set of 7 annotated screenshots that were intended to be used on the web… I don’t know the originating program (although I know it was on Mac OS X).

The various compressions used were Pngcrush (a command-line utility), grip OptiPNG (drag-and-drop utility), The GIMP (image editing program), and (oddly enough) Microsoft Paint for Windows Vista. For The Gimp & Paint, compression was achieved by just opening the file and then saving over it (doing a “Save As” in GIMP and just a “Save” in Paint).

Long story short: OptiPNG is the best, but Paint had the exact same compression level. Here’s where it gets weird… to get the same compression out of Paint that OptiPNG achieved, you need to open and save the file 3 times. I do not know why.

[Compression method]: [total size of all seven files after compression]

  • Uncompressed Files: 265k
  • The GIMP: 235k
  • Pngcrush: 230k
  • OptiPNG: 229k
  • Paint (one compression): 254k
  • Paint (two compressions): 233k
  • Paint (three compressions): 229k
  • Paint (four compressions): 229k

MS Paint must have undergone some serious changes to its PNG support for the Vista version. Even though it matches the best compression, I’m still fairly baffled as to why this takes three rounds.

In the end, OptiPNG is the winner in my semi-scientific test. If I had a larger data-set, this would be a little more valid. If people find this useful and are still curious, let me know and I’ll run the same tests on a much larger dataset.

Hope this helps!

2 thoughts on “PNG Compression

  1. Pingback: Image Compression at Wikia

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