Batch Resize Pictures in Mac OS X Using Automator
Need to resize a ton of pictures on a Mac? Instead of downloading a third party application or using Preview, you can use Automator to handle the entire operation, even renaming the images to indicate they have been resized to a new resolution.
Automator is included in every Mac OS X installation’s /Applications/ folder and is simple to use, making it an excellent tool for repetitive tasks like this. If you’ve never used Automator before, don’t worry, we will walk through the entire process to get it working, and the result will be a simple app that resizes any images that are dragged and dropped onto it.
How to Resize a Group of Pictures with an Automator App on Mac
This will build a little Mac application that has drag and drop support, the result is that files that are dropped into it will be automatically resized.
- Launch Automator and select to create a new Application
- From the left side Library menu, click on “Files & Folders” then double-click on “Ask for Finder Items”
- Now on the right side set the “Ask for Finder Items” choice to ‘Start at’ the Desktop and then click the checkbox next to “Allow Multiple Selection”
- Next, from the same Files & Folders menu, find and double-click on “Copy Finder Items”
- From the right-side pull-down menu alongside “To” choose “Other” and create a new folder called “Resized”
- Optional: Again from the library, double-click on “Rename Finder Items” to add that action as well
- Optional: From the pull-down menu choose “Add Text” and in the box below add “-resized” to appear after the file name
- Now click on “Photos” from the left side Library menu, then double-click on “Scale Images”, and select the resized pixel width of images
- Run the workflow to test it, otherwise choose “Save” to create an application that allows for drag & drop resizing of groups of images
If you want the resized images to appear in the same location as the origin folder, choose “Variable” and “Path” as the ‘To’ folder in “Copy Finder Items”, if you choose this option you should be sure that you add the Rename action so that you don’t accidentally overwrite any existing files.
Once the Automator workflow has been saved as an application, you can keep the app on your desktop or Dock and then drag and drop pictures onto it to resize automatically.
Optional: Create a Service for Batch Resizing on Mac Instead
Another option is to go the “Services” route instead, which adds the ‘Resize” option to the right-click contextual menus of Mac OS X.
To do that, start from the first step but instead of choosing an “Application” in Automator, choose to create a “Service” instead. Save as usual, then just select multiple files in the file system, right-click the group of images, and you’ll find the new Batch Resize option, which when selected runs through the resizing process automatically.
It’s that easy, so the only decision to make is whether you want it in the alternate-click menu or as a standalone app with drag and drop support.
Not a fan of Automator, or would prefer another option? You can resize groups of images manually in Preview too, though it won’t be quite as automated it still handles batch processing bulk photos just fine. Also, you can tweak and resize images from the command line tool sips, which requires usage of the Terminal and thus may be considered more advanced, but it can be scripted which makes it incredibly useful as well. With so many options included natively in Mac OS X, there is really no reason to download a third party app to perform these tasks on a Mac.