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What FREE software (included with Mac OS X, or public domain) would be a good, simple way to take some existing PNG clipart files and do some simple editing?

I really only need to do 3 things:

  1. Rotate the image.
  2. Clip the image.
  3. Set a "transparent" color.

I don't need anything that takes weeks to learn or is super-powerful or super expensive.

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closed as off-topic by Raystafarian, fixer1234, nc4pk, DavidPostill, mdpc Jan 12 at 0:50

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Is there a TRUE Mac OSX version of Gimp??? > Running GIMP on Mac OS X requires Apple's X11 environment. > It is included on the "Optional Installs" package on the OS > X install disk – Margret May 17 '10 at 5:11
Yes, Gimp requires the X11 environment, but Seashore does not. – Mitch Dempsey May 17 '10 at 5:15
We can't possibly install all that on every Mac... just to run Gimp. I'll check-out Seashore instead. (I'm VERY surprised that my simple request is so "nearly impossible" to find. I would think there would be dozens of software packages that could do that.) – Margret May 17 '10 at 19:04
@Julie To be fair, setting a PNG transparency colour is not a standard or simple feature, since unlike GIF images, the PNG format features a full alpha channel to enable many colours to have various levels of transparency. – ghoppe May 17 '10 at 20:39
Gimp no longer requires X11. It is now native. Go get it. – user155494 Aug 30 '12 at 18:35

Have a look at This is a simple little tool.

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I can't find the "transparent" feature. Or does it not have one? – Margret May 17 '10 at 19:03

You could do most of those things with the Preview application on OS X.

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I really need to do THREE things... not "some of them". Does Preview have a hidden "transparency feature" that I can't find? – Margret May 17 '10 at 19:02
Preview supports the "Instant Alpha" feature, which you can get to by holding down the Select drop-down button. I can't say whether that is exactly what you need, though. – ayaz May 18 '10 at 13:09

Not free, but I like Pixelmator a lot; it's a native Mac Photoshop clone, and it's reasonably cheap (about $60; it was on sale for half price at MacUpdate over the weekend, I'm hoping it shows up there again).

On Windows at work I use Paint.NET, but the Mac port of Mono isn't up to running it yet.

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Have you looked at iPhoto? I can't remember if iPhoto does transparency.

But the Gimp is available for mac and easy to install. You can use Mac Ports or download it at the Gimp on Mac.

Gimp requires x11. Which is included with Snow Leopard. It's isn't a big deal to use or install. You do not have to do anything special to use it. Just launch the Gimp and it will launch x11.

If xll isn't on the machine, you can find it on the Snow Leopard install disc.

Let me stress this, you are not gonna find anything else that's open source (free) that does what the Gimp does. Running X11 is a SMALL price to pay to get all that free functionally.

There are several cheap alternatives to Photoshop too. Like Pixelmator. If you want a native mac app.

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I second Pixelmator as a cheap alternative. It isn't free but very cost effective for the features. – Insomnic May 18 '10 at 14:56

pixen looks like it has those features (but - I'm not any kind of a graphic artist!): I see 90-deg (but not arbitrary angle) rotation, transparent color layers, cutting and cropping.

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You could try ImageMagick. It's command-line software rather than an app, and the learning curve is concomitantly steeper. But, since you have such a well-defined set of actions you want to take, learning how to do just those manipulations wouldn't be too hard.

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Preview has a transparency feature

All you have to do is pull up the image in preview, making sure it's in PNG format, then widen the preview window on the bottom right to see other buttons not readily seen in normal frame.

You will see select button, click the pull down menu where you'll see instant alpha. Put the cursor on the area you want to make transparent, hold mouse down on that area and move mouse to fill area while holding mouse. The area will turn a orange color. Then hit delete, while holding mouse or orange will disappear, for areas to tiny or missed just use the rectangular selection and hit delete.

It actually works great I use it all the time.

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For changing all of a specified colour to transparent, pngweasel is excellent. From the developer's page:

pngweasel is a fun little Mac OS X utility we put together to handle a common Web developer's task: converting an image to the PNG image format and making parts of the image's background transparent. It's lightweight, it's free, it's easy to use, and yes, there is a weasel.

Also reviewed at

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