1. Go to the target folder
cd /path/to/your/images
Example:
cd ~/Desktop/site-images
2. Inspect image properties
sips -g pixelWidth -g pixelHeight -g format *.png
Full metadata for one file:
sips -g all image.png
3. Convert filenames to lowercase (optional but highly recommended)
Prevents broken links on Linux web servers
for f in *; do mv “(echo “$f” | tr ’[:upper:]’ ’[:lower:]’)” done
4. Replace spaces with hyphens (recommended for web publishing)
for f in *\ *; do mv “{f// /-}” done
5. Resize large PNG images
Example: maximum width = 1600 px, preserving aspect ratio
mkdir -p resized
for f in *.png; do sips -Z 1600 “f” done
6. Convert PNG → JPEG for photos/screenshots
(Usually much smaller for internet publishing)
mkdir -p jpg
for f in *.png; do sips -s format jpeg “{f%.png}.jpg” done
7. Compress JPEG quality
Recommended web range: 70–85
mkdir -p jpg-compressed
for f in jpg/*.jpg; do sips -s formatOptions 80 “(basename “$f”)” done
8. Strip unnecessary metadata (recommended)
mkdir -p clean
for f in *.png; do sips —deleteProperty profile “f” done
9. Normalize PNG color profile to standard sRGB
Important for consistent browser rendering
mkdir -p srgb
for f in *.png; do
sips -m /System/Library/ColorSync/Profiles/sRGB\ Profile.icc
“f”
done
10. Quick size comparison
du -sh .
Detailed per-file sizes
ls -lh
11. Find suspiciously huge images (>5 MB)
find . -type f -size +5M
12. Final recommended structure before upload
original/ → untouched originals
resized/ → resized PNG
jpg/ → converted JPEG
jpg-compressed/ → final optimized web images
clean/ → metadata-cleaned images
srgb/ → color-normalized images
============================================
Typical practical workflow
============================================
Photos/screenshots:
PNG → resize → JPEG → compress
Diagrams/plots/text-heavy graphics:
PNG → resize only
Transparent graphics/logos:
Keep PNG
Scientific figures:
Usually PNG preferred
Final upload target:
jpg-compressed/ or resized/
============================================
13. One-line “quick web normalization” example
Resize + convert to JPEG + quality 80
mkdir -p web
for f in *.png; do tmp=“web/{f%.png}.jpg" sips -Z 1600 "f” —out “tmp” —out “$tmp” done