Let’s say you’re writing a series of Blender tutorials and you’re using PrintScreen to grab screen shots. Unfortunately, this gives you a Pictures directory filled with massive images not optimized for uploading to, and displaying on, a web page. The last thing you want to do is resize them manually. You’re in luck! With the ImageMagick
-resize option, you can quickly and easily batch scale those images to a manageable size.
Place all the images you want to scale in a directory and navigate to that location via command line. Then enter:
mogrify -resize 960x528 *.png
This command resizes all of the .png files in your directory to a size of 960 pixels by 528 pixels. Perhaps the height isn’t as important as the width. You can simply enter:
mogrify -resize 960 *.png
This will scale all of your images to a width of 960 pixels, the height will be scaled accordingly, preserving the aspect ratio. Perhaps you have a height and width you are aiming for, but want to preserve the aspect ratio. You can enter:
mogrify -resize 960x528! *.png
When and where possible this will scale your images to 960 by 528 pixels, but will preserve the aspect ratio of those images that won’t scale to these dimensions exactly.