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I am trying to figure out how to do batch processing with ImageAlpha. I really like this program but I cannot figure out how to do this. Just to be clear I am trying to convert several images from PNG24 to PNG8.

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This doesn't seem to be a programming question, and is therefore off-topic. You might want to try Super User, but you will have to add a lot more detail than "cannot figure out how to do this" before reposting. – Josh Caswell Sep 14 '12 at 17:35

migrated from stackoverflow.com Sep 15 '12 at 0:13

1 Answer

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According to the ImageAlpha site:

Batch processing
ImageAlpha is mostly based on pngquant. You'll find compiled pngquant executable in ImageAlpha.app/Contents/Resources directory.

e.g.

ImageAlpha.app/Contents/Resources/pngquant -ext 8bit.png yourInputImage.png

For more options run:

ImageAlpha.app/Contents/Resources/pngquant -h

Goodluck

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Thank you for the help but my problem is that I don't know how to run the executable. I can get as far as opening the executable but then where to go from there I have no idea. When I open the pngquant executable it says "process completed logout" and I can't type anything more in that window. – Stephen Sep 14 '12 at 21:06
You execute the application from Terminal. Run Terminal.app (from Applications/Utilities) and use the commands above. Note that you must either cd to the directory that contains ImageAlpha.app first or prepend the path...for example, if ImageAlpha.app is in /Applications, try this in Terminal: /Applications/ImageAlpha.app/Contents/Resources/pngquant -h – George Profenza Sep 14 '12 at 21:20
It looks like you've never used the commandline before on osx. There are plenty of tutorials out there. The above will become trivial once you've understood the basics (navigating to a directory, running an application, using flags) – George Profenza Sep 14 '12 at 21:24
I tried doing all of the things that have been recommended and after I run the the executable I followed this tuturial <ethangardner.com/articles/…; and it keeps saying pngquant: command not found? – Stephen Sep 14 '12 at 21:37
either it's a typo: should be pngquant, not ngquant, either you're trying to run the command from a path different from where pngquant lives. Note that the tutorial you've picked is for Windows and CommandPrompt uses different commands from Terminal (although a few are similar). Maybe it's easier to add pngquant to the system path so you can call the application from anywhere on the system. Try this in Terminal: sudo pico ~/.bash_profile - this should open a text editor. Add/Append this to the file export PATH=/Applications/ImageAlpha.app/Contents/Resources/:$PATH then exit (Ctrl+X) & save – George Profenza Sep 14 '12 at 21:42
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