Image optimization improves two things simultaneously: page speed (Core Web Vitals)
and image search rankings. Both affect overall organic visibility.
Image Format Selection
WebP: Best choice for most images. 25-35% smaller than JPEG at similar quality.
Browser support: All modern browsers. Use as primary format.
AVIF: Even smaller than WebP. Growing browser support (Chrome, Firefox, Safari 16+).
Use: When file size is critical and browser support is sufficient.
JPEG: Still appropriate for photographs without transparency. Widely supported.
PNG: For images requiring transparency. Use SVG instead for logos/icons when possible.
Alt Text for SEO
Alt text: Describes the image content. Serves two purposes:
- Accessibility: Screen readers read alt text to visually impaired users.
- SEO: Google reads alt text to understand image content.
Good alt text: Descriptive and specific. "Google Ads campaign dashboard showing ROAS metrics"
Bad alt text: "image1.jpg" or "image" or a keyword stuffed phrase.
Empty alt text (alt=""): Use for purely decorative images. Tells screen readers to skip.
Filename Optimization
File name: Contributes to image SEO. Use descriptive, hyphenated names.
Good: "google-ads-quality-score-components.jpg"
Bad: "IMG_2047.jpg"
Core Web Vitals Image Optimization
LCP is often an image: Preload the LCP image with <link rel="preload" as="image">.
CLS from images: Always specify width and height attributes to reserve space.
Lazy loading: Use loading="lazy" for all below-fold images.
Image optimization for SEO and Core Web Vitals: yositeup.com
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