How To Easily Change The File Type Of A Folder Full Of Images [OS X Tips]

Batch Processing Pixelmator

One of the things we get a lot here at Cult of Mac, especially in our coverage of games, is folders full of promotional images. Now, for a variety of reasons, we often need to change the type of those images from, say, PNG to JPG files.

You can use Preview, of course, opening them all at once, and then selecting them all, then exporting them all to a new folder with a new image type. It’s workable, but it’s tedious.

Using Pixelmator, an affordable image editing program for the Mac, Automator (no relation), a scripting app bundled in Mac OS X, and Alfred, a pretty slick app launching application, you can make these changes much faster.

Here’s how.

First up, be sure to grab a copy of Pixelmator from the Mac App Store. At $15, it’s a powerful Photoshop-style image editor that works incredibly well.

While you’re there, grab a copy of the excellent app launcher, Alfred. I honestly can’t say enough about how great it is.

Then, locate Automator on your Mac. On mine, it’s in the Applications folder. Double click to launch Automator and you’ll see an option to choose what kind of project you want to create. Click on Application, and then the Choose button.

In the far left column, you’ll see the Files and Folders category. Click that, and then find the Get Selected Finder Items in the column just to the right. Drag that over into the editing window on the right.

Next, click on the Library category in the far left column, and type the text string “change” into the search box above the columns. You’ll see an option with the Pixelmator icon on it called Change Type of Images. Drag that to the editing window to the right, as well.

This step is totally up to you.

This step is totally up to you.

You’ll get a little dialog box that asks if you want to add a step to copy the Files and save them. I chose not to add that step; you can choose on your own.

Change the file type to whatever you want in the pop up menu in this final step. You’ll have the choice of Pixelmator, Photoshop, JPEG, PNG, or TIFF image formats.

Now, you should now have an application that will take the Finder items you select and change their type to your preferred format. Save the Automator file somewhere on your Mac, making sure it’s saved as an Application. Give it a name you’ll remember, like “Batch Images Convert.” Quit Automator.

Now, open a folder full of images in the Finder. Select them all, and then hit your Alfred activation keyboard shortcut (I use Control-Space). Type in the name of your recently saved Automator app, and when you see it in the main Alfred window, hit Enter on your keyboard. Alfred will launch your Automator application, which will then change all your selected files to your preferred image type, and you’ll be all done.

From now on, then, all you need to do is this final step. Select your images, launch Batch Images Convert with Alfred, and you’re done. Hoorah!

Grab Alfred for free and Pixelmator for $15 in the Mac App Store.

About the author

Rob LeFebvreAnchorage, Alaska-based freelance writer and editor Rob LeFebvre has contributed to various tech, gaming and iOS sites, including 148Apps, Creative Screenwriting, Shelf-Awareness, VentureBeat, and Paste Magazine. Feel free to find Rob on Twitter @roblef, and send him a cookie once in a while; he'll really appreciate it.

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