This will create folders big, full, medium and small and adds images of size 1620px, 1920px, 1024px and 450px width in them. $ cd some-image-folder $ create_image_sizes Removing whitespace is as easy as mogrify -trim *. Yet when working with GUI editor, it is very easy to save the image with extra unnoticed whitespace. Such images are harder to position and make responsive. When coding, image with whitespace is hardly ever useful. convert source.jpg -shave 10x10 output.jpg #shave 10px from sides Trimming whitespace ![]() ![]() If you just need to strip some border from the image, it is more useful to use -shave. The +0+0 means y=0, x=0 so that we will get a closest tile from the center (actual center of the image). That’s where - gravity comes into play: convert source.jpg -crop 100x100+0+0 -gravity center output.jpg This can be useful, but in real world scenario, what you often need is just one image cropped from the center. If the source image is 1000x1000, it will not output one image, but ten of them. convert source.jpg -crop 100x100 output.jpg Default usage may not be totally intuitive though. Cropping with the help of gravityĬrop with mogrify and convert is very similar to resize. It’s main advantage is that it is installed on MacOS by default. Sips also can do also rotates and flips but generally it is less flexible than ImageMagick. sips -resampleWidth 1024 *.jpg sips -resampleHeight 768 *.jpg sips -z 768 1024 *.jpg # -z takes height as a first argument Same as mogrify, it replaces images in place. It can take values in several formats: mogrify -resize 50% *.jpg # resize to 50% mogrify -resize 1024x768 *.jpg # resize, keep original aspect ratio mogrify -r 1024x768! *.jpg # resize, enforce exact dimensions mogrify -r 1024 # resize to width of 1024 mogrify -r x768 *.jpg # resize to height of 1024 convert source.jpg -r 1024x768 output.jpgĪn alternative solution for resizing can be the sips command which is only available on MacOS. Mogrify equivalent for that would be: mogrify -format jpg *.png Resizing and aspect ratioįor a lot of people, resizing is by far the most common image transformation.īoth convert and mogrify have the -resize (-r) argument available. This will convert the image from PNG to JPG. With convert you can specify a single source and output filename. This will, for example, resize all images in current folder to 256 * 256. Therefore it is good habit to backup those images beforehand. Mogrify generally takes the same arguments as convert, but allows you to process multiple images and replace them in place. ImageMagick provides you with two powerful commands: convert and mogrify. That can easily be done with Brew: brew update & brew install imagemagick ![]() Sometimes it also needs to be installed on MacOS. You most likely already have it installed, but on some Linux distributions you might need to install it yourself: sudo apt-get install imagemagick ![]() The library that enables the image processing is mostly ImageMagick. (That generally means you need a MacOS, Linux or Ubuntu on Windows). These are of course for BASH, not Windows CLI. There are a couple command line commands that can help you do most of the basic operations. Chances are, that if you can explain the task in a few words, it is also simple to do in the command line. And doing changes to multiple images at once is problematic. But still the simple process of opening the image and saving it is something that just takes too much time. Maybe with some practice you learn some key combos to do things faster. Obviously you have to spend some time clicking around. One solution is to start an image GUI editor of choice, change the image and save it. Sometimes it’s PNG while it should have been JPG, sometimes the image has unnecessary whitespace or it has a wrong color. At first it was really enjoyable but soon a first problem has arisen: exported images do not often come in the right form. Save time by transforming images in the command lineĪfter a few months of mostly programming I took a step back this month to do regular HTML/CSS coding.
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