Image optimisation workflow for retina displays
Introduction. When designers target modern devices, the pixel density of retina screens demands that images look sharp without bloating page load times. This article walks through a step‑by‑step workflow that balances visual fidelity and performance, explaining why each stage matters to both user experience and SEO rankings. Whether you’re a front‑end developer or a content manager, understanding how to serve high‑resolution assets efficiently will keep your site fast, engaging, and search‑friendly.
Assessing image requirements
The first task is to know what each image must achieve on retina displays. Consider the element’s size in CSS pixels, its placement (hero banner vs. thumbnail), and whether it appears on high‑resolution devices only. This assessment informs the scale of the source file you need to create.
- Measure the display area in pixels before creating assets; avoid guessing.
- Determine if a single image can serve both standard and retina screens using CSS media queries.
Creating source files at double resolution
To ensure crispness on high‑density displays, export images at twice the intended display size. For example, a thumbnail that shows as 150 × 100 pixels in the browser should be exported at 300 × 200 pixels. This guarantees that the device’s pixel ratio can map one CSS pixel to two physical pixels without blurring.
| Item | What it is | Why it matters |
|---|---|---|
| Double‑size export | Source image at twice CSS dimensions | Prevents pixelation on retina screens |
| Compression level | Optimized file size with quality loss <10% | Reduces load time without visible artifacts |
| File format choice | JPEG for photos, PNG or WebP for graphics | Matches content type and device support |
Generating responsive image variants
After exporting the double‑size source, create two key variants: one at full size for retina displays and a downscaled version for standard screens. Use an automated tool or build script to batch‑process these files, ensuring consistent naming conventions (e.g., hero@2x.webp, hero.webp). This step enables browsers to pick the most appropriate file via the srcset attribute.
Implementing srcset and sizes
Embed the variants in HTML using srcset so the browser automatically selects the correct resolution based on device pixel ratio. Pair it with a sizes attribute that describes how wide the image will appear at different viewport widths. This declarative approach eliminates manual JavaScript hacks and improves page rendering speed.
Avoiding common pitfalls
Many teams mistakenly serve only high‑resolution images, causing unnecessary bandwidth usage. Others use outdated formats like PNG for photos, which inflates file size. Finally, neglecting to test on actual retina devices can hide pixelation issues until after launch. Address these by (1) verifying srcset functionality in dev tools, (2) preferring modern formats such as WebP or AVIF when supported, and (3) performing cross‑device quality checks.
Conclusion. By carefully measuring image dimensions, exporting at double resolution, generating responsive variants, and leveraging srcset, you can deliver retina‑ready visuals that stay sharp and load quickly. Implementing this workflow not only satisfies modern device standards but also boosts SEO through faster page speeds and better user engagement. Start today by auditing your current image assets and applying these steps to one high‑traffic page.
Image by: Steve Johnson
