Your Mac comes with several powerful tools that make resizing and converting images fast and convenient. These include workflow tools like Automator and Shortcuts and the basic Apple Preview image viewer.
Resize manually using the preview
If creating Automator workflows or shortcuts seems too much work and all you want to do is resize a single image, the Apple Preview app included with macOS can do what you’re looking for.
Any image file opened in the preview can be resized using the preview. Unless you’ve changed the default file associations for your Mac, double-clicking the image file should open it in Preview (alternatively, you can right-click and choose Open In > Preview).
Open the file and click Tools > Adjust Size at the top of the screen. You can choose from predefined sizes to fit your image, specify your own dimensions or change the file resolution. You can also click the “lock” icon to scale the vertical and horizontal axes independently, but be aware that this will distort the image.
When you’re done, press Command+S to save the file.
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Resize images to a set size using Automator
Let’s say you run a blog and often convert images to a certain width or height. Every time you want to perform this action, you can open the image editor or save time with Automator and create a quick action that you can access from the right-click menu (two-finger click).
To do this, launch Automator and choose “Quick Action” when prompted.
At the top of the workflow area, change “Workflow accepts current” to “image files” and enter “Finder” as the application. Use the “Image” drop-down list to select the icon you want to assign to the action and adjust the color if desired.
Go to the “Finder” group on the left, then click and drag “Get Specified Finder Items” to the main workflow menu.
Now click on the “Photos” group and add a “Scale Images” action to your workflow. You’ll be asked if you want to add an action that saves a copy of your image before you change it, which you can do if you want. (We decided to skip this in our workflow).
Now enter the desired size in pixels or percentage. If you are selecting pixels, keep in mind that it applies to both axes. For example, if you enter 1200 pixels, a landscape image will be scaled down to 1200 pixels wide, while a portrait image will be scaled down to 1200 pixels tall.
Now press Command+S to save the quick action. The name you choose is the label you’ll see in the Finder, so make sure you’re happy with it.
You can now use your action by right-clicking (or clicking with two fingers) on the image file in the Finder, then selecting “Quick Actions” and following the workflow you just created.
Resize images to your own size with Automator
The beauty of the previous workflow is its one-click access. You can select a bunch of images and resize them to a set size virtually instantly. But it’s also possible to create a simple Automator workflow that prompts you for a custom size, which requires one more step to execute.
First, follow the steps in the previous section to create the same workflow, then return your attention to the “Scale Images” section. Click on “Options” and then make sure that the “Show this action when the workflow starts” box is checked. This tells macOS to ask for your input at this stage of the workflow.
You can also specify a “default” size in the “Image Scale” section, which will be pre-populated when the workflow starts. Now press Command+S and give your workflow a name you’re happy with.
Now select an image (or group of images) in the Finder, right-click, and under “Quick Actions” select the workflow you just created. When you start the workflow, you will be prompted for a size and then the images will be resized.
Resize images using shortcuts
Like Automator, Shortcuts can automate a large number of repetitive actions. Anecdotally, it’s a bit slower than Automator, but it’s a viable option if you don’t understand Automator. You can also download a finished event and make changes to it.
To create an image resizing workflow, open Shortcuts and create a new blank workflow. To the right of the workflow, click the “Shortcut Details” icon (it looks like a set of sliders), then make sure “Use as Quick Action” and “Finder” are checked. If you leave “Services” checked and the action also appears in other apps like Safari.
Now look at the main workflow area. Change “Receive Any” to “Receive Images” so that the shortcut only appears when selecting image files.
Now click the “Action Library” button in the panel to the right of the workflow (looks like a box with stars). Search for “resize” and drag the “Resize Image” action into the workflow window.
You can now choose between a predefined width or height (as specified by you), or you can choose to have the workflow prompt you for custom dimensions each time. If you want to be asked every time, right-click on the width field (it will be 640 by default) and choose Insert Variable > Always Ask. If you want, do the same with the height.
If you go this route it will use “Auto Width” and “Auto Height” where you don’t specify any variable. So if you want to resize the image to 500 pixels tall, you can leave the “Width” prompt blank and simply enter “500” at the height prompt. The shortcut will scale the second axis accordingly.
Finally, search for “save” and drag the “Save File” action into the workflow window. Click the “Options” button to turn off “Ask where to save” if you want to specify a specific location each time (such as the Desktop folder).
Now double-click the “New Shortcut” placeholder at the top of the window and name your workflow. You can also change the associated icon and color if you want.
After selecting the image file, you can now find your workflow in the “Quick Actions” menu after right-clicking. You can click the Share button to copy the link to your workflow and share it with your friends. Click here to download the above workflow.
Create a “Convert to JPEG” or similar quick action
macOS already includes a “Convert Image” quick action that you can enable in System Preferences (System Settings) > Extensions > Finder, which prompts you for the image type and general size when converting an image.
However, if you want a faster way to convert an image to a specific type (such as JPEG), you can create an Automator workflow to do so. This works great for converting HEIC images taken on the iPhone to full size JPEGs with minimal issues.
Open Automator and select Quick Action when prompted. At the top of the workflow, make sure “Image files” and “Finder” are selected in the appropriate dropdown box. You can also customize the icon and color if you want.
In the “Finder” group of the Actions Library, drag “Copy Finder Items” to the main workflow area. You can either specify the location or use the “Show this action when the workflow starts” switch in the “Options” section if you want to be prompted every time.
Go to the “Photos” group in the Actions Library and drag “Change Image Type” to the workflow area. Enter the type of image you want to use, here we use JPEG.
Now press Command+S to save your quick action with a suitable label. You can now find it in the “Quick Actions” menu when you right-click an image file in the Finder. Since we are copying the file, your original image will not be affected.
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Convert PDF to images in one click
If you want to quickly convert all pages in a PDF to images, you can do so using a Quick Action. First, start Automator and make sure that “Workflow receives current” points to “PDF Files” and that “Finder” is selected in the application drop-down list. If you want, give your workflow a suitable icon and color.
In the “PDF” group of the Actions Library, drag “Render PDF Pages as Images” to the main workflow window. Enter the image type, resolution and compression level you want to use.
Go to the “Finder” group in the Actions Library and drag “Move Finder Items” into the workflow window. This will save the resulting images to a location you specify, or you can enable “Show this action when the workflow starts” in the “Options” section to be prompted every time.
Press Command+S to save your workflow, label it “Convert PDF to Images” and it will appear in the “Quick Actions” menu when you right-click (or double-tap) a PDF file in the Finder.
Customize quick actions
You can add and remove quick actions in System Preferences (System Settings) > Extensions > Finder. To remove something you don’t find useful, uncheck it. You can also change the order in which your Quick Actions appear by clicking and dragging them.
The quick actions you have created will be saved in the
~/Library/Services/ folder, accessed by launching the Finder and then clicking Go > Go to Folder at the top of the screen. Double-clicking an action will open it in Automator so you can make changes.
Renaming a quick action in this folder doesn’t always change the label in the Quick Actions menu, so you may need to copy and paste the steps into a new Quick Action and then delete the old one if you want to change its name. .
Get more done with shortcuts
Automator may seem intimidating at first, but it’s a powerful tool worth exploring. Hopefully, the above workflows will help you create your own time-saving automation.
Shortcuts is another app that can help you save time. Check out (and download) some of our favorite macOS shortcut workflows.
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