This is a fast and easy way to scale the size of an image (or a bunch of images) using OS X’s built in utility Automator.  It is very simple (also crude), but it works and the results are pretty decent.

(You can scroll down to the end of the post if you just want the Automator applications and don’t care how I got there.)

First set up the job in Automator by opening the application in /Applications:

Automator Location

Next, choose workflow from the opening screen and select choose (or just hit enter if they’re already highlighted):

Automator Template Chooser

The next screen has built in functions to select by category.  In the first column, select “Files & Folders“.  Column 2’s selections are based upon what you select in column 1.  Now the next additions to your workflow will depend upon your desired task.  If you’d like to convert a single image, or if you plan on converting a bunch of images in a folder.

First we’ll cover how to make a simple workflow that you can use to select one image, start the workflow, and exit Automator.

With “Files & Folders“ selected in the first column, drag “Get Selected Finder Items“, followed by “Copy Finder Items” into the right hand area.

Next, in the first column, select Photos.  Find “Scale Images” and drag that to the right hand actions area, so it is at the bottom.  Your workflow should look like this:

Workflow to Scale a Selected Image

Next, we want to adjust an options on  ”Copy Finder Items” and “Scale Images”  to force the workflow to ask for a values, rather than having to manually open Automator, change them, and click “Run”.  That Would be tedious, and we are looking for simple.  So, click the options button in the “Copy Finder Items” and ”Scale Images” portions of your workflow, and click the check box “Show This Action When Workflow Runs” in both of them:

Setting Automator To Ask For Values

With that done, just use the “Save As” in the file menu (⇧⌘S) and save the file as an application:

Save Automator Workflow As Application

That’s it, really.  You can now drag an image file onto the new application, it will ask you where to save the resized image, as well as ask you for the type of scale.  You can set by percentage, or by pixels, and set the value based upon how you chose to scale it.  Scaling by pixels appears to be based upon the width, and then uses the same scale factor to the height automatically.

Now, you can adjust this application to do a whole batch of files inside a folder, if you’d like.  First, open Automator, click “Open Existing Workflow”, and choose your new application created above.  Drag “Get Folder Contents” and place it under “Get Selected Finder Items” in the workflow.  Your new workflow should look like this:

Workflow To Scale A Folder Of Images

Again, click “Save As” in the file menu, and select a new name for this application.  You can now drag a folder of images and drop it on the application to resize a batch of images.

There are other options in the Photos section of the Library of actions (the left hand column) such as changing the file type as well, for instance if you have a bunch of jpg’s and want to make them png’s for the web.

I hope this gets you interested in Automator–a totally useful and underrated tool–and happy image scaling!

Download the Single File Application or the Folder of Images Application here if you’d like. You can update and change them by opening them with Automator.