H8 — Chapter 8 - Images

Criterion H8 : Contextual images — guide + checklist

PART 1 - Fundamentals Chapter 8 - Images Keyword : images contextuelles

This criterion seems “simple”, but it creates many discrepancies in production.

The **H8 — Contextual images** criterion is part of our SEO checklist (335 criteria). Here, you have a **practical** method to check and fix it — with a concrete example.

What exactly this criterion covers

This criterion seems “simple”, but it creates many discrepancies in production.

**H8 — Contextual images** (Chapter 8 - Images): images relevant to surrounding content, no generic stock

Why it matters (SEO + UX)

Why it matters: it is a UX point that eventually translates into SEO. When poorly applied, we often observe: ambiguity (wrong associated query), duplication between pages, or loss of performance on Core Web Vitals.

On volume-generated sites, this criterion also serves as a **safeguard**: a stable rule avoids 1,000 errors at once.

How to check (step by step)

Approach: tool-assisted test (validator / performance). Recommended tool: **ImageOptim**.

  1. Open the page in Chrome → DevTools → Performance/Network tab.
  2. Run WebPageTest and note the main weak point.
  3. Check if the problem repeats on templates.

Tip: first isolate 10 “representative” URLs (top pages + generated pages) before scaling the fix.

How to fix properly

Strategy: apply a rule, then check neighboring pages.

  • Convert to WebP/AVIF + compress (Squoosh/ImageOptim).
  • Add width/height to avoid CLS.
  • Write a contextual alt (useful, not keyword-stuffed).

Then: re-crawl 50–200 URLs, then monitor Search Console for 7–14 days (impressions/CTR/indexing).

Concrete example (illustrative)

Example (illustrative):

  • **Context**: category page for SEO training in Lille
  • **Before**: PNG images 2–4 MB, no explicit dimensions.
  • **After**: WebP/AVIF conversion + dimensions + descriptive alt (context: category page).
  • **Note**: Goal: reduce weight and improve rendering (and sometimes image search).

Checklist to tick

  • [ ] Optimized weight
  • [ ] Respects: no generic stock
  • [ ] Modern format
  • [ ] Defined dimensions
  • [ ] Useful and contextual alt
FAQ

Frequently asked questions — H8

What is the most common mistake on “Contextual images”?

Trying to “optimize” by adding too many keywords, which degrades readability and creates repetitions.

Which tool is the fastest for large-scale checking?

For this type of criterion, a crawl (e.g. Screaming Frog) + targeted verification in ImageOptim is usually the fastest combo.

How to prevent this from recurring on 10K generated pages?

Freeze an auto-generation rule (title/structure/schema/URLs) + add automatic control (crawl or test) before production import.

Ready to go from theory to action?

Validate this criterion with an audit, then deepen the method in the Academy.

Audit with the tool → Learn in the Academy →