Handy Image Utility: PNGOUT

I heard about PNGOUT awhile ago but never really bothered to look into it. Sure, it can compress my PNG's but Fireworks does a decent job of that already. But in the comments of my last post, Which Image Format is Best, somebody again made mention of it.

The original utility is a command line tool but the guy who made it, Ken Silverman, also started up a company to produce a commercial version of it. PNGOUTWin is a Windows application that offers a nice GUI interface along with batch processing capabilities.

This is pretty handy at the end of a project to just drag all the PNGs from a folder into the app, get them shrunk, and then upload to the live server. I tried it quickly on my corporate page and noticed that it managed to compress my files anywhere from 5% to 15%. That's a decent result.

Much of this compression is due to removing internal comments and data that is not necessary, including gamma information. Internet Explorer can have issues with PNGs as background graphics and tends to render them darker than they should be. Removing the gamma data ends up solving this problem.

This inexpensive utility could likely find its way into my regular arsenal of tools.

Published August 31, 2006 · Updated September 14, 2006
Categorized as Design
Short URL: https://snook.ca/s/659

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11 Comments · RSS feed
Richard Herrera said on August 31, 2006

Well I'll ask the ovbious: is there a GUI version for Mac? I'm not at all comfortable with the command line.

Jonathan Snook said on August 31, 2006

Unfortunately, there isn't currently a Mac version available but there is mention that a Mac version is in the works.

Kanashii said on August 31, 2006

There's also the open source utility PNGCrush which can be compiled on any platform.

Lim Chee Aun said on September 01, 2006

Wow, PNGOUT is free but the GUI version is not?

And uh, how do you know removing the gamma data can solve that problem? Maybe I'm a little lost here...

Jonathan Snook said on September 01, 2006

Lim: I think that's a fair tradeoff to have to pay for a GUI version. $20 certainly isn't an unreasonable price to pay for software.

As to the gamma issue, it is known that IE renders PNGs as too dark as background graphics due to gamma. Check out this test page. In IE6/7 you'll notice that a number of images fail because of the gamma correction whereas the PNG with no gamma correction renders correctly. And having tested it on my own site, I can confirm that removing the gamma information from the PNG solved my problem.

Mitchell Lane said on September 01, 2006

PNGGauntlet is also a Windows GUI for PNGOut, and it's completely free. It works pretty well, in my experience.

Mike said on September 03, 2006

For someone who makes image utilities, he sure has a terrible background image on his site.

Kelly Miyashiro said on September 03, 2006

I haven't seen a method to use transparent PNGs for a background in IE and having text selectable above it at the same time. Does such a method exist?

Ali B. Gismok said on September 06, 2006

Kelly, inerhit divs are the key, and usage of IE6 specific CSS (turn background-image: none for IE and let filter do the thing).

Michael Bester said on September 06, 2006

There is PNGCrusher for the Mac which gives rudimentary GUI access to the OptiPNG command line tool. Basically, you just drag PNG files onto the application icon - if it can compress the file any further, it will overwrite the original file with the compressed one.

It works very well in my experience, creating file size savings similar to what Jonathan mentions above.

Dgimis said on November 18, 2008

good guest page.
thank you.

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