Automate image size in Preview

The AppleScript dictionary for Preview is just abysmal and won't give you access to the image size panel in the application. It may be more straightforward to use Apple's scriptable image processing system (sips) to achieve this image manipulation goal. In the Terminal:

/usr/bin/sips -s format jpeg -s formatOptions 100 --resampleWidth 2048 -s dpiWidth 72.0 -s dpiHeight 72.0 --out newImg.jpg inImg.jpg

As an example, my portrait inImg.jpg has dimensions 3888 x 5184 and is a 300 DPI image. When I run the preceding sips command line above on it, the output newImg.jpg is 1365 x 2048 and 72 DPI. The sips utility does not work on camera RAW images.

I have a working Shortcuts Quick Action that takes one or more selected non-RAW images in the Finder and outputs the above settings with a filename of originalname_2048_72.ext. The original image is untouched.

I have only tested this Shortcut in macOS Sequoia v15.3.1. When you click that link, Shortcuts will offer to install the Shortcut for you. I have named it: Resample Image to 2048 px. You can edit it by right-clicking on the Shortcut and choosing Edit…

The sips(1) man page can be opened from your browser in a separate Terminal window with:

x-man-page://sips

or from the Terminal with the following command sequence:

mandoc -Tpdf -mdoc $(man -w sips) | open -f -a Preview



You can edit the Shortcut that I provided and omit the --out content. The "${f}" is the given input image.

Sips will just overwrite the input JPG with your preferred changes. Optionally, and for organizational purposes, you might put the original images in a folder named 2048_72, select all of the images in that folder, and run the Shortcut on them en masse.

The assumption is that you are using the Quick Action with existing JPG images that you intend to overwrite with JPG data per the SIPS changes. It will explode if you start with a camera RAW image (e.g. CR3, NEF, ARW, etc), or a non-JPG raster image as SIPS cannot overwrite a non-JPG image with designated JPG content. This would work using the --out syntax as I have successfully used a camera RAW source file and used a --out JPG result file.

Here is the revised Shortcut link that has removed the --out content.

I have some JPG images here where the Shortcut also misbehaves and I have no answer to why that is so.