Image Optimization Check

The image optimization check validates whether your website uses properly optimized images that load quickly and provide good user experience across all devices.

What this check validates

• ✅ Modern formats - Uses efficient formats like WebP, AVIF when supported
• ✅ Proper compression - Images are compressed without significant quality loss
• ✅ Appropriate sizes - Images match their display dimensions
• ✅ Alt text present - All images include descriptive alt attributes
• ✅ Lazy loading - Non-critical images load only when needed

Why image optimization matters

• Page Speed: Optimized images significantly reduce loading times
• User Experience: Faster loading improves engagement and reduces bounce rates
• SEO Benefits: Page speed is a Google ranking factor
• Accessibility: Alt text helps screen readers describe images to visually impaired users
• Bandwidth Savings: Smaller files reduce data usage, especially on mobile

What optimized images look like

Modern image implementation with optimization:

<!-- Responsive image with modern formats -->
<picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="image.jpg" 
       alt="Descriptive text about the image"
       width="800" 
       height="600"
       loading="lazy">
</picture>

<!-- Simple optimized image -->
<img src="optimized-image.webp" 
     alt="Clear description of image content"
     width="400" 
     height="300"
     loading="lazy">

Optimization techniques

<!-- Responsive images for different screen sizes -->
<img srcset="small.webp 480w, 
             medium.webp 768w, 
             large.webp 1200w"
     sizes="(max-width: 480px) 100vw, 
            (max-width: 768px) 50vw, 
            33vw"
     src="medium.webp"
     alt="Product showcase image"
     loading="lazy">

<!-- Background images with optimization -->
<div style="background-image: url('hero.webp'); 
            background-size: cover;">
</div>

Best practices

• Choose right format: WebP for photos, SVG for icons and simple graphics
• Compress effectively: Balance file size with visual quality
• Size appropriately: Don't serve larger images than display size
• Add alt text: Describe image content for accessibility
• Implement lazy loading: Load images only when they enter viewport

Common issues

• Oversized images: Serving 2000px images for 300px display areas
• Uncompressed files: Large file sizes without optimization
• Missing alt text: Images without descriptive alt attributes
• Old formats: Using only JPEG/PNG instead of modern formats
• No lazy loading: All images load immediately, slowing page speed
• Missing dimensions: Images without width/height attributes cause layout shifts