Optimizes images for web performance using modern formats, responsive techniques, and lazy loading strategies. Use when improving page load times, implementing responsive images, or preparing assets for production deployment.
Install
npx skills add https://github.com/secondsky/claude-skills --skill image-optimizationSKILL.md
Image Optimization
Optimize images for web performance with modern formats and responsive techniques.
Format Selection
| Format | Best For | Compression |
|---|---|---|
| JPEG | Photos | Lossy, 50-70% reduction |
| PNG | Icons, transparency | Lossless, 10-30% |
| WebP | Modern browsers | 25-35% better than JPEG |
| AVIF | Next-gen | 50% better than JPEG |
| SVG | Logos, icons | Vector, scalable |
Responsive Images
<picture>
<source srcset="image.avif" type="image/avif">
<source srcset="image.webp" type="image/webp">
<img
src="image.jpg"
srcset="image-400.jpg 400w, image-800.jpg 800w, image-1200.jpg 1200w"
sizes="(max-width: 600px) 100vw, 50vw"
alt="Description"
loading="lazy"
decoding="async"
>
</picture>
Lazy Loading
<!-- Native lazy loading -->
<img src="image.jpg" loading="lazy" alt="Description">
<!-- With blur placeholder -->
<img
src="placeholder-blur.jpg"
data-src="image.jpg"
class="lazy"
alt="Description"
>
Build Pipeline (Sharp)
const sharp = require('sharp');
async function optimizeImage(input, output) {
await sharp(input)
.resize(1200, null, { withoutEnlargement: true })
.webp({ quality: 80 })
.toFile(output);
}
Performance Targets
| Asset Type | Target Size |
|---|---|
| Hero image | <200KB |
| Thumbnail | <30KB |
| Total images | <500KB |
Optimization Checklist
- Use WebP with JPEG fallback
- Implement responsive srcset
- Enable lazy loading for below-fold
- Compress at quality 70-85
- Serve from CDN
- Set proper cache headers
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