One test file of mine which is a 93kb .png compressed to a maximum of 73kb with pngout and punyPNG it was 62kb….

the overal rundown (in same order as your benchie) was: 24%, 47%, 13%, 36%, 62%, 10%, 66%, 31%, 26%

*as you see, the only big exception is the butterfly image, which for some reason doesn’t get good compression on any of the standard tools [my best guess is that your tool is applying mixed filters whereas other tools apply the same filter over the whole file]

Punypng will have Animated PNG (APNG) support in the near future as well.

Here’s some usefulness of an online image crusher:
1. Most people are in need of a one-stop shop to compress all your images: GIF, PNG, and JPEGs. Currently, there’s no single offline tool that does all three formats which compression comparable to the popular libraries (PNGSquash comes close). I was a big fan of Smush.it until they removed the upload feature in favor of YSlow integration which is why punypng fills in that niche nicely.

2. If you want to get decent file support at the command line, you will need ImageMagick which is a nightmare to install plus you’ll need serious scripting abilities (kinda disqualifies most people I know).

3. Punypng’s API is in the works, and once that’s in place, you should be able to get image compression in any of your CMSes, like WordPress. Joost de Valk from Yoast emailed me this morning to start that discussion.

4. As with any online service, you get quick incremental improvements without having re-install anything on your desktop. I don’t know of any tool out there that supports Dirty Transparency, for example.

In general, you don’t crush *every* image on your site, nor is it worth the time and energy. But if you have sprites and heavy UI elements, it matters, and a free tool like punypng addresses that need perfectly. I was able to cut our UI assets on Ask.com by half using punypng, cutting our initial load times in half. As a top 10 internet destination, that translates into real cost-savings.

Dictionary.com got similar results using punypng. Wikipedia will get punyified assets in a month or so thanks to GreenReaper’s effort. Evite is on it’s way as well.

Right…

What I want is an application that I can run on my servers (windows for development and linux for production) that I can run to resize all of my images, and then for the production servers have cronjobs that take the resized images (PNG, GIF, JPG) and compress them, replacing the original file. Is that so difficult to ask?

Heck, right now I am using PHP’s GD functions to handle the resizing. So just having something that can be run any any server as a cron job for compression would be ideal. With many of these compression scripts they seem to do only png or only jpg, etc… not ideal.

Punypng was not able to compress it any further than I already did.

For the butterfly image, I’d be interested to see how the ImageMagick+OptiPNG combo works on the original image, rather than the post-optimized one … I’d be surprised if OptiPNG can reduce it more. I think much of the savings you were able to get were due to the ImageMagick bit depth reduction rather than the -o7 option, which raises a good point that @masterwujiang suggested regarding quantization. At Ask.com, our sprites have to be lossless since every pixel counts, but I’m definitely thinking about doing some better quantization techniques now!

@mastersuwjiang: totally agree with pngnq.. .it rocks. I’ve been looking into quantization, and it’s probably the next thing that punypng is going to consume to get some more puny love.

@kyriakos: I hear you re: the lack of previews. They’re on their way… many others have asked for them ;)

@ck2 and @StanAngeloff: ImageOptim which I do benchmark here (http://www.gracepointafterfive.com/punypng-benchmarks) does the shotgun approach and uses Optipng, Pngcrush, Pngout, and AdvComp. I think punypng fares well against them, especially on transparent images through the dirty transparency support. I’d be interested to hear what kind of results you get using punypng vs the others.

Ill check out punypng, seems pretty cool and I am usually looking to get every byte out of the band.