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Optimize PNG and JPEG images locally using pngquant and mozjpeg/jpegtran — TinyPNG-level compression without API keys.
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| name | image-optimize |
| description | Optimize PNG and JPEG images locally using pngquant and mozjpeg/jpegtran — TinyPNG-level compression without API keys. |
| version | 1.0.0 |
Compress PNG and JPEG images locally. Achieves 60–80% size reduction with no visible quality loss.
brew install pngquant mozjpeg
Verify:
pngquant --version # 3.0.3+
/opt/homebrew/opt/mozjpeg/bin/jpegtran -version
# Single file, overwrite in place
pngquant --quality=75-90 --speed=1 --force --output image.png image.png
# All PNGs in a directory
for f in /path/to/dir/*.png; do
before=$(stat -f%z "$f")
pngquant --quality=75-90 --speed=1 --force --output "$f" "$f"
after=$(stat -f%z "$f")
pct=$(( (before - after) * 100 / before ))
echo "$f: $(( before/1024 ))KB → $(( after/1024 ))KB (-${pct}%)"
done
| Use case | --quality |
|---|---|
| Blog covers, hero images | 75-90 |
| Product/portfolio (high quality) | 85-95 |
| Thumbnails, icons | 65-80 |
JPEGTRAN=/opt/homebrew/opt/mozjpeg/bin/jpegtran
# Single file
$JPEGTRAN -copy none -optimize -progressive -outfile output.jpg input.jpg
# All JPEGs in a directory, overwrite in place
for f in /path/to/dir/*.jpg /path/to/dir/*.jpeg; do
[ -f "$f" ] || continue
before=$(stat -f%z "$f")
$JPEGTRAN -copy none -optimize -progressive -outfile "$f.tmp" "$f" && mv "$f.tmp" "$f"
after=$(stat -f%z "$f")
pct=$(( (before - after) * 100 / before ))
echo "$f: $(( before/1024 ))KB → $(( after/1024 ))KB (-${pct}%)"
done
#!/bin/bash
# Usage: optimize-images.sh /path/to/dir
DIR="${1:-.}"
JPEGTRAN=/opt/homebrew/opt/mozjpeg/bin/jpegtran
total_before=0; total_after=0
for f in "$DIR"/*.png "$DIR"/*.PNG; do
[ -f "$f" ] || continue
before=$(stat -f%z "$f")
pngquant --quality=75-90 --speed=1 --force --output "$f" "$f"
after=$(stat -f%z "$f")
total_before=$((total_before + before))
total_after=$((total_after + after))
echo "PNG $f: $(( before/1024 ))KB → $(( after/1024 ))KB (-$(( (before-after)*100/before ))%)"
done
for f in "$DIR"/*.jpg "$DIR"/*.jpeg "$DIR"/*.JPG "$DIR"/*.JPEG; do
[ -f "$f" ] || continue
before=$(stat -f%z "$f")
$JPEGTRAN -copy none -optimize -progressive -outfile "$f.tmp" "$f" && mv "$f.tmp" "$f"
after=$(stat -f%z "$f")
total_before=$((total_before + before))
total_after=$((total_after + after))
echo "JPEG $f: $(( before/1024 ))KB → $(( after/1024 ))KB (-$(( (before-after)*100/before ))%)"
done
if [ $total_before -gt 0 ]; then
echo ""
echo "Total: $(( total_before/1024 ))KB → $(( total_after/1024 ))KB (-$(( (total_before-total_after)*100/total_before ))%)"
fi
| Format | Average reduction |
|---|---|
| PNG (pngquant lossy) | 60–75% |
| JPEG (jpegtran lossless) | 5–20% |
| JPEG (cjpeg lossy) | 30–60% |
--output equals input — use --force flag.stat -f%z gives file size in bytes (Linux uses stat -c%s).