What is Image Optimization?
Image optimization is the process of reducing image file sizes while maintaining acceptable visual quality. It involves choosing the right format, compressing images, resizing to appropriate dimensions, and using modern formats like WebP and AVIF.
How Does Image Optimization Work?
Images typically account for the largest portion of a web page's total size, often 50% or more. Unoptimized images can dramatically slow down page loads and waste bandwidth. Image optimization techniques include choosing the right format (JPEG for photographs, PNG for graphics with transparency, SVG for icons), compressing with tools like ImageOptim or SharpJS, and serving appropriately sized images using responsive images with srcset.
Modern image formats like WebP and AVIF offer significantly better compression than JPEG and PNG while maintaining equivalent quality. WebP typically achieves 25-34% smaller file sizes than JPEG, and AVIF can be even smaller. Using the HTML picture element, you can serve modern formats to browsers that support them while providing fallbacks for older browsers. Automated image optimization in your build pipeline or through a CDN with image transformation capabilities is the most sustainable approach.