How to optimize image for websites from the command line
Estimated reading time: 2 minutesWhen hosting your website with a lot of images, your users need a lot of bandwidth just to load some images, but most of the time the image doesn’t need to be that big for the user to load. Here is a guide on how to optimize images for these kind of situations, credits to Eric Murphy. I typed the video in text format as it is such a good video that I want to take notes of that.
- Install imagemagick
sudo pacman -S imagemagick
Optimise JPGs
convert image.jpg -resize 400x400 image.min.jpg # resize image as you don't always need that big
convert image.jpg -quality 75 image.min.jpg # reduce quality of image, 75% is a good compromise between file size and quality
convert image.jpg -strip image.min.jpg # remove metadata (eg camera details, location, etc.)
convert image.jpg -sampling-factor 4:2:0 -strip -quality 75 -interlace JPEG -colorspace sRGB -resize 0 converted.jpg # best for web quality wise
You can make it into a shell script
#!/bin/sh
convert $1 -sampling-factor 4:2:0 -strip -quality 75 -interlace JPEG -colorspace sRGB -resize $2 $3
Optimise PNGs
Mostly same as JPGs
Optimise batch of files at a time
mogrify -sampling-factor 4:2:0 -strip -quality 75 -interlace JPEG -colorspace sRGB -resize 400 -path "opt" *.jpg # converting all jpgs and put all converted jpgs into opt folder
Optimise SVGs
First install svgo with npm
npm i -g svgo
Then run
svgo logo.svg -o logo.min.svg
Batch convert SVGs
svgo -f ./assets/svgs -o ./assets/optimiszedsvgs # -f specifiying the directory and -o is the output directory