Macos – Resize images via drag and drop on OSX with good quality

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I want to be able to drag and drop images on an application(icon) which preferably doesn't run. This application has to resize the images to 600x450px and drop them somewhere.

I already created an Automator action which does exactly that but the quality is less then stellar compared to having it resized via the Preview-function or Photoshop. Below you can find an example pictures resized in Automator and Photoshop.

While there are Photoshop Automator Actions they aren't compatible with Photoshop CS6 yet.

So for now I'm looking for something else which does the job with good quality and compression.

Automator resized picture
Automator resized picture

Photoshop resized picture
Photoshop resized picture

Best Answer

You could also use ImageMagick in an Automator application:

/usr/local/bin/mogrify -filter Lanczos2 -resize 500x -format jpg -quality 96 -path ~/Desktop/ "$@"

The default filter for downscaling images is Triangle, which often makes images look too blurry without additional sharpening in my opinion. Triangle is similar to the resizing methods used by Automator and sips. I usually use Lanczos2 (2-lobe Lanczos), which makes images less sharp than Lanczos (Lanczos3 or 3-lobe Lanczos). Lanczos2 is almost identical to Catrom, and it is also similar to the bicubic option in Photoshop.

You can add sharpening with something like -sharpen 0x0.4+0.8. 0 sets an automatic radius for the convolution kernel, 0.4 is the radius, and 0.8 is the amount.

You can compare the different filters with a command like this:

for f in Bartlett Blackman Bohman Box Catrom Gaussian Hanning Hermite Lagrange Lanczos Lanczos2 Mitchell Parzen Point Robidoux Sinc Spline Triangle Welsh; do convert -filter $f -resize 50% input.png $f.png; done

I uploaded a comparison of different resizing options at


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