Batch resising for web
Sun 05 October 2025
Smaller environment (Photo credit: wikipedia)

I recently tried to measure the environmental impact of this website. I used an online tool. The result shows the easiest way to improve my score was to reduce image sizes. This could easily be done with ImageMagick.

I wrote a small bach script to resize my files:

#!/bin/bash

# resize images for web use

target_size=200 # in kb
output_dir="web"
mkdir -p $output_dir

resize_image() {
    echo "image $1..."
    output_file=$output_dir/$1
    cp "$1" "$output_file"
    current_size=$(( $(stat -c%s "$output_file") / 1024 ))
    factor=95
    while (( current_size > target_size ))
    do
        echo "current size: $current_size"
        current_size=$(( $(stat -c%s "$output_file") / 1024 ))
        magick "$1" -resize $factor% "$output_file"
        factor=$(( factor - 5 ))
    done
}

for image in *jpg
do
    resize_image "$image"
done

It tries several resize factor (while loop, factor being redefined line 20) until the output size is lower than a predefined threshold.

Then, I needed to replace path in all my articles.

Category: how to Tagged: bash jpg magick web blog how to

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