I'm looking for a tool that can help reshape images to specific dimensions, but I'm not sure if there's a term easy to search for tools that support that.

Preview can resize images to specific dimensions, but at the cost of losing dimension ratio. However you can create a square here in preview to specify how to crop, then to zoom in our out of image to get the crop you want, however you cannot specify that crop dimensions, only the image dimensions.

Is there a software or a key term for feature that can help you specify crop dimension? (not image dimension)

Example: Here I have to carefully drag the border to make it a square, but is there a way to create a crop area with predefined dimensions?]

enter image description here

  • Also - dozens of related questions with answers on the side bar here to the right: apple.stackexchange.com/questions/11238/…
    – bmike
    Nov 18, 2017 at 16:13
  • @bmike I'm not asking about automation. I'm asking about the ability to specify crop dimension
    – Iancovici
    Nov 18, 2017 at 17:04
  • Yes, you program the dimensions into the tool so you don’t need to use a mouse or do you not know how to crop in photos app or acorn or Pixelmator and just need an app suggestion?
    – bmike
    Nov 18, 2017 at 18:14
  • I was wondering about existing application, if I resort to programming scripts for automation, I can just resort to openCV
    – Iancovici
    Nov 19, 2017 at 12:52

1 Answer 1


Depending on your needs you might resize all images first, then specify the crop and potentially resize again after if needed. It's really up to your workflow which operation needs to happen in which order.

enter image description here

Photos manually (which also has a very nice square crop tool and can export and re-sample the image if needed). The next step would be to have automator or AppleScript control Photos (or your editor of choice) to make entering specific dimensions easier. If you don't mind shell scripting, the tool I've used to script this for many images is https://www.imagemagick.org/

You can get it with https://brew.sh and install quite easily. You should spend 10 minutes installing brew and the command line tools (free) from Apple and skip installing Xcode unless you feel you want the whole developer toolset. That might take 30 minutes or more to install.

There are dozens of tutorials on how to do this - here are three:

  • Does it let you choose what part you want to keep in the cropped area?
    – Iancovici
    Nov 18, 2017 at 16:22
  • @Iancovici - Like Blade Runner where you speak and ask to enhance on the fly, no. Like if you know the coordinates or can do math to specify what you want to keep, yes.
    – bmike
    Nov 18, 2017 at 16:52

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