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February 16, 2026

Image SEO: How to Optimize Images for Search Engines in 2026

Everything that actually matters for image SEO in 2026: alt text, file naming, sitemaps, structured data, page speed, and how Google's AI Overviews pick images.

S
Sirv Team

Google Images accounts for over 20% of all web searches. For e-commerce, that traffic converts. People searching for product images are often ready to buy. Yet most websites treat image optimization as an afterthought, leaving a huge chunk of qualified traffic on the table.

This guide covers every aspect of image SEO that matters in 2026, including how Google’s AI Overviews are changing which images get surfaced in search results.

Why Should You Care About Image SEO?

Image search isn’t just Google Images anymore. Product images show up in Shopping results, AI Overviews, rich snippets, and knowledge panels. Google Lens processes billions of queries per month. If your images aren’t optimized, you’re invisible across all of these surfaces.

The fundamentals haven’t changed. But the bar has risen. Google now uses sophisticated computer vision models to understand image content, which means your technical SEO signals need to match what the image actually shows.

File Naming Conventions

Your image filename is one of the first signals Google uses to understand what an image depicts. Rename files before uploading.

Good filenames:

red-running-shoe-nike-pegasus.jpg
stainless-steel-french-press-1-liter.jpg
manhattan-skyline-sunset-2026.jpg

Bad filenames:

IMG_20260115_092344.jpg
photo-1.jpg
DSC0042_final_v2_EDIT.jpg

Rules to follow:

  • Use hyphens to separate words (not underscores or spaces).
  • Include the primary keyword naturally.
  • Be descriptive but concise. 3 to 6 words is the sweet spot.
  • Avoid generic terms like “image,” “photo,” or “picture.”
  • Use lowercase letters only.

File name is a super minor ranking factor though. If you have thousands of images and don’t have an easy way of renaming them, don’t bother. It’s not worth it.

Alt Text Best Practices

The alt attribute remains the single most important image SEO element. It serves two purposes: accessibility for screen readers and context for search engines.

Good vs. bad alt text

<!-- Bad: empty or missing -->
<img src="shoe.jpg" alt="">
<img src="shoe.jpg">

<!-- Bad: keyword stuffing -->
<img src="shoe.jpg" alt="running shoe shoes buy running shoes best running shoe cheap running shoes">

<!-- Bad: too vague -->
<img src="shoe.jpg" alt="shoe">

<!-- Good: descriptive and natural -->
<img src="shoe.jpg" alt="Nike Pegasus 42 running shoe in red, side profile view">

<!-- Good: contextual for e-commerce -->
<img src="shoe.jpg" alt="Nike Pegasus 42 men's running shoe in university red colorway">

How to write good alt text

  1. Describe what the image shows, not what you want to rank for.
  2. Include the product name and key attributes (brand, model, color, size) for product images.
  3. Keep it under 125 characters. Screen readers may truncate longer text.
  4. Skip “image of” or “photo of”. The browser already knows it’s an image.
  5. For decorative images, use an empty alt (alt="") so screen readers skip them. These images don’t need SEO value.
  6. Each image on the page should have unique alt text. Duplicate alts dilute value and confuse screen readers.

Image Sitemaps

A standard XML sitemap helps Google discover your pages. But an image sitemap makes sure your images get indexed too. This is especially important when images are loaded dynamically (via JavaScript) or hosted on a CDN.

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
        xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">
  <url>
    <loc>https://example.com/products/running-shoe</loc>
    <image:image>
      <image:loc>https://cdn.example.com/images/red-running-shoe.jpg</image:loc>
      <image:title>Red running shoe front view</image:title>
    </image:image>
    <image:image>
      <image:loc>https://cdn.example.com/images/red-running-shoe-side.jpg</image:loc>
      <image:title>Red running shoe side profile</image:title>
    </image:image>
  </url>
</urlset>

You can include up to 1,000 images per page entry. For e-commerce sites with hundreds of product images, this is essential. Make sure every product image you want indexed appears in your sitemap, even if it’s served from a CDN subdomain.

Structured Data for Images

Structured data helps Google understand the context of your images and can unlock rich results like product carousels.

Product schema with images

{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Nike Pegasus 42",
  "image": [
    "https://example.com/images/nike-pegasus-42-front.jpg",
    "https://example.com/images/nike-pegasus-42-side.jpg",
    "https://example.com/images/nike-pegasus-42-sole.jpg"
  ],
  "description": "Men's road running shoe with responsive ZoomX foam cushioning.",
  "brand": {
    "@type": "Brand",
    "name": "Nike"
  },
  "offers": {
    "@type": "Offer",
    "price": "139.99",
    "priceCurrency": "USD",
    "availability": "https://schema.org/InStock"
  }
}

Including multiple images in the image array gives Google options for different display contexts (carousels, knowledge panels, AI Overviews).

ImageObject for editorial content

For blog posts and articles, use ImageObject to provide explicit metadata:

{
  "@context": "https://schema.org",
  "@type": "ImageObject",
  "contentUrl": "https://example.com/images/manhattan-skyline.jpg",
  "creditText": "John Smith Photography",
  "copyrightNotice": "2026 John Smith",
  "acquireLicensePage": "https://example.com/licensing"
}

Google uses creditText and license information to display attribution in image search results, which builds trust and drives more clicks.

Page Speed and Image Optimization

Google has confirmed that page speed is a ranking factor. And images are usually the biggest bottleneck. Here’s what matters.

Serve next-gen formats

WebP and AVIF offer 25-50% smaller file sizes than JPEG at the same quality. Use the <picture> element for manual implementation:

<picture>
  <source srcset="product.avif" type="image/avif">
  <source srcset="product.webp" type="image/webp">
  <img src="product.jpg" alt="Product photo" width="800" height="600" loading="lazy">
</picture>

Or let an image CDN handle format negotiation automatically. Sirv, for example, detects browser support via the Accept header and serves AVIF, WebP, or the original format without any markup changes on your end. One URL, best format every time.

Compress appropriately

Aim for the smallest file size that doesn’t produce visible artifacts. For product photography, a quality setting of 75-80 (on a 0-100 scale) is usually the right balance. For decorative backgrounds, you can often push to 60-70 without anyone noticing.

Properly size images

Serving a 3000px-wide image to a 400px container wastes bandwidth and slows the page. Use srcset to let the browser pick the right size:

<img
  srcset="product-400.jpg 400w, product-800.jpg 800w, product-1200.jpg 1200w"
  sizes="(max-width: 600px) 400px, (max-width: 1024px) 800px, 1200px"
  src="product-800.jpg"
  alt="Product photo"
  width="800"
  height="600"
  loading="lazy"
>

Responsive Images and SEO

Google crawls with both mobile and desktop user agents, but mobile-first indexing means the mobile version of your page is what counts. Make sure your responsive image setup serves appropriate images for mobile viewports, not just scaled-down desktop images.

Key things to get right:

  • Use srcset with width descriptors so the browser picks the best size.
  • Don’t hide images on mobile via display: none. If Googlebot’s mobile crawler can’t see the image, it won’t index it.
  • Test with Google’s Mobile-Friendly Test and check that product images render correctly.
  • Art direction (different crops for mobile vs. desktop) is fine. Use the <picture> element with media queries.

How Does Google Pick Images for AI Overviews?

Google’s AI Overviews are now a major feature in search results, and they prominently display images alongside AI-generated summaries. Getting your image selected for an AI Overview can drive serious traffic.

Here’s what we know about how Google selects images for AI Overviews:

  1. High-quality, original images rank higher. Stock photos and generic illustrations are rarely selected. Unique product photography and original diagrams perform best.
  2. Images from pages that rank well organically have a strong advantage. Image SEO and page SEO are deeply connected.
  3. Structured data matters. Pages with proper Product, HowTo, or Article schema are more likely to have their images pulled into AI Overviews.
  4. Image relevance to the query is everything. Google’s vision models evaluate whether the image actually matches the search intent.
  5. Multiple high-quality images per page give Google more options to match different queries.

The takeaway: invest in original, well-optimized product photography. A single set of great images with proper SEO markup can appear across standard results, image search, shopping, and AI Overviews.

CDN URLs and SEO

Serving images from a CDN is a performance best practice, but it raises questions about domain signals.

Same-origin vs. CDN subdomain

Google handles CDN-hosted images well, but there are nuances:

  • Custom subdomain (e.g., images.yoursite.com): Best option. Google associates images with your domain. Set this up as a CNAME pointing to your CDN.
  • CDN domain (e.g., yoursite.sirv.com): Works fine for indexing. Google follows image URLs across domains and attributes them to the page they appear on.
  • Make sure CDN images are crawlable. Check that robots.txt on your CDN domain doesn’t block Googlebot.

Canonical considerations

If the same image appears on multiple pages, Google decides which page to associate it with. Use these strategies:

  • Link the highest-priority page in your image sitemap.
  • Use canonical tags on pages to consolidate duplicate product pages.
  • Keep your primary product images on the canonical product page, not just on category pages.

Start With an Audit

Image SEO is a compound investment. Each optimization (descriptive filenames, strong alt text, structured data, fast delivery) reinforces the others. The sites that rank well in image search, product carousels, and AI Overviews are the ones that get all of these basics right, consistently.

Pick your top-traffic pages first. Check alt text, verify images appear in your sitemap, add structured data where it’s missing, and confirm your images load fast across devices. For the performance side, an image CDN like Sirv can handle format conversion, responsive resizing, and global delivery automatically, letting you focus on the content and markup that search engines need.

The traffic opportunity in image search is real and growing. The sooner you get these fundamentals right, the more surfaces your content will show up on.

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