Image Optimizer

Image optimization toolkit using Sharp for high-performance WebP conversion, thumbnail generation, and intelligent background removal.

Quick Start

All scripts are in scripts/. Use pnpm to run them:

# Basic WebP conversion (large images)
node scripts/optimize-images.js

# Small images (higher quality)
node scripts/optimize-small-images.js

# Advanced with custom config
node scripts/optimize-images-advanced.js

Thumbnail Generation

Generate thumbnails with specific dimensions or aspect ratios:

# Square thumbnails (128x128)
pnpm optimize:128

# Square thumbnails (256x256)
pnpm optimize:256

# 16:9 aspect ratio (640x360 default)
pnpm optimize:16-9

# Process specific files
pnpm optimize:128 public/image.png public/logo.png

# Custom options
node scripts/optimize-thumbnails.js --size=128 --dir=public/icons

Aspect Ratio Thumbnails

Generate thumbnails with preset aspect ratios:

# 16:9 (widescreen, YouTube)
pnpm optimize:16-9 --size=small    # 640x360
pnpm optimize:16-9 --size=medium   # 800x450
pnpm optimize:16-9 --size=large    # 1920x1080

# 4:3 (traditional, iPad)
pnpm optimize:4-3 --size=medium    # 800x600

# 1:1 (square, Instagram)
pnpm optimize:1-1 --size=large     # 1080x1080

# Custom dimensions
node scripts/optimize-aspect-ratio.js --width=1280 --height=720

Background Removal

Remove white backgrounds with smart edge smoothing:

# Basic white to transparent
pnpm optimize:128 public/product.png --transparency=white-to-transparent

# High quality for product photos
pnpm optimize:256 public/product.jpg \
  --transparency=white-to-transparent \
  --threshold=250 \
  --quality=90

# Custom threshold for off-white backgrounds
pnpm optimize:128 public/icon.png --transparency=white-to-transparent --threshold=230

Configuration

WebP Quality

• 85-90: Product photos, high-quality images
• 75-85: Standard web images (default)
• 60-75: Thumbnails, non-critical images

Fit Strategies

• cover: Fill entire area (recommended, exact dimensions)
• inside: Maintain aspect ratio, may not fill completely
• fill: Force stretch (distorts, not recommended)

Crop Position

• entropy: Smart crop, keeps subject (recommended)
• center: Center crop
• attention: AI attention-based (requires Sharp 0.29+)
• top, bottom, left, right: Edge-aligned

Transparency Modes

• auto: Auto-detect based on input (PNG/WebP preserve, others remove)
• preserve: Keep existing transparency
• remove: Remove transparency, fill with background color
• white-to-transparent: Smart white background removal
• add: Add transparency with alpha level

Background Removal Options

• --threshold: White threshold (0-255, default 240). Use 230-245 for off-white, 250-255 for pure white
• --smooth-edges: Enable edge smoothing (default true)
• --supersample: 2x supersampling for smooth edges (default true)
• --gaussian-smoothing: Use 5×5 Gaussian kernel (default true, false=3×3 simple)
• --smoothing-iterations: Edge smoothing passes (default 1, max 2)

Common Use Cases

E-commerce Product Photos

# Remove white background, high quality
pnpm optimize:256 public/products/*.jpg \
  --transparency=white-to-transparent \
  --threshold=250 \
  --quality=90 \
  --supersample=true \
  --gaussian-smoothing=true

Blog Thumbnails (16:9)

# Generate 16:9 thumbnails for blog posts
pnpm optimize:16-9 --size=medium --dir=public/blog-images

Social Media Avatars (1:1)

# Square thumbnails for profiles
pnpm optimize:1-1 --size=large --dir=public/avatars

Icon Optimization (128×128)

# Small square icons
pnpm optimize:128 public/icons/logo.png --transparency=preserve

Processing Directories

Batch process entire directories:

# Process all images in a directory
node scripts/optimize-thumbnails.js \
  --dir=public/uploads \
  --size=256 \
  --output=public/thumbnails

# With background removal
node scripts/optimize-thumbnails.js \
  --dir=public/products \
  --size=512 \
  --transparency=white-to-transparent \
  --threshold=245

Tips

1. Use supersampling for product photos to eliminate jagged edges
2. Higher quality (90+) for images that will be further edited
3. Standard quality (75) for final web images
4. Entropy position preserves important image content
5. Test thresholds on sample images before batch processing
6. Lower threshold (230-240) for off-white backgrounds
7. Higher threshold (250-255) for pure white backgrounds

Dependencies

All scripts require:

pnpm add sharp

Sharp is a high-performance Node.js image processing library.