Image optimization mistakes to avoid (and how to fix them)

Quick Summary (TL;DR)

Avoid serving oversized images, using wrong formats, missing responsive techniques, and ignoring modern image formats. Fix by implementing responsive images with srcset, using WebP/AVIF formats, compressing images properly, adding width/height attributes, and implementing lazy loading. These fixes can reduce image payload by 70-90% while maintaining visual quality.

Key Takeaways

Oversized images: The most common mistake - serving desktop-sized images to mobile devices, wasting bandwidth and slowing page loads
Wrong format choice: Using JPEG for graphics with text or PNG for photographs, missing opportunities for better compression with WebP/AVIF
Missing dimensions: Not including width and height attributes, causing layout shift and poor user experience during image loading

The Solution

Image optimization mistakes significantly impact page performance and user experience. The solution involves implementing a comprehensive image strategy that addresses format selection, responsive sizing, compression, loading techniques, and modern browser capabilities. By fixing these common mistakes, you can dramatically reduce page weight and improve loading times without sacrificing visual quality.

Implementation Steps

Fix Oversized Images Implement responsive images using srcset and sizes attributes to serve appropriately sized images based on viewport and device pixel ratio. Use image processing tools or CDN services to generate multiple sizes automatically.
Adopt Modern Image Formats Implement WebP as primary format with JPEG fallback, add AVIF support for modern browsers, and use picture element to serve optimal formats. Modern formats can reduce file sizes by 25-50% compared to JPEG/PNG.
Implement Proper Compression Use tools like Squoosh or ImageOptim to compress images without visible quality loss. Aim for 70-85% quality for JPEGs and use lossless compression for PNGs when transparency is needed.
Add Width and Height Attributes Always include width and height attributes on img tags to prevent layout shift. Use aspect-ratio CSS for responsive containers and maintain consistent image dimensions across different sizes.
Implement Strategic Lazy Loading Use native loading=“lazy” for below-the-fold images, combine with Intersection Observer for better control, and implement progressive loading with low-quality image placeholders (LQIP).

Common Questions

Q: How do I choose between WebP and AVIF? Use AVIF as primary format for modern browsers (Chrome, Firefox) with WebP fallback for Safari and older browsers. AVIF typically offers 20-30% better compression than WebP but has less browser support.

Q: Should I optimize all images to the same quality level? No, adjust quality based on image content and importance. Use higher quality (85-90%) for hero images and product photos, lower quality (70-80%) for decorative images and thumbnails.

Q: How do I handle images in CMS or user-generated content? Implement automatic image optimization at the CDN level, use responsive image services like Cloudinary or Imgix, and set up image transformation pipelines that optimize images on the fly.

Tools & Resources

Squoosh - Web-based image compression and format conversion tool
Cloudinary - CDN with automatic image optimization and transformation
ImageOptim - Mac app for lossless image compression
Lighthouse - Audit image optimization and identify improvement opportunities

Performance & Loading

Image & Media Optimization

Infrastructure & Mobile

Need Help With Implementation?

While these fixes address common image optimization mistakes, implementing a comprehensive image strategy requires understanding your content types, user devices, and performance goals. Built By Dakic specializes in helping teams implement efficient image optimization workflows that balance quality with performance. Get in touch for a free consultation and discover how we can help you achieve optimal image performance across your entire application.