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Useful-scripts/image_compress.sh
2026-03-19 10:46:02 +01:00

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#!/bin/bash
input="$1"
output="$2"
target_size=$3
if [[ -z "$input" || -z "$output" || -z "$target_size" ]]; then
echo "Usage: $0 input output.jpg <target size in bytes>"
exit 1
fi
compress_and_get_size() {
local q=$1
magick "$work" -strip -interlace Plane -quality "$q" "$output"
stat -c%s "$output"
}
work=$(mktemp --suffix=.jpg)
cp "$input" "$work"
magick "$input" \
-auto-orient \
-colorspace sRGB \
-strip \
-background white -alpha remove -alpha off \
"$work"
echo "Trying to fit below $target_size bytes"
while true; do
# Binary search
low=1
high=95
best_q=1
while (( low <= high )); do
mid=$(((low + high) / 2))
size=$(compress_and_get_size "$mid")
echo " Quality $mid -> $size bytes"
best_size=$size
if (( size <= target_size )); then
best_q=$mid
low=$((mid + 1))
else
high=$((mid - 1))
fi
done
echo "Best quality this round: $best_q ($best_size bytes)"
if (( best_size <= target_size )); then
echo "DONE: $output is $best_size bytes"
break
fi
echo " Reducing resolution"
tmp=$(mktemp --suffix=.jpg)
magick "$work" -resize 75% -quality 85 "$tmp"
mv "$tmp" "$work"
done
rm -f "$work"