1 in 5 Website Images Are Invisible to Google: How to Improve Image SEO

If you think your images are helping your SEO, think again.

According to WebAIM’s 2025 Million accessibility report, which analyzed the top one million websites, 18.5% of home page images are missing alt text entirely. That’s nearly one in five images that search engines simply can’t understand.

And the problem gets worse when you dig deeper. When researchers looked beyond just missing alt text to include questionable or repetitive alternatives, they found that nearly one-third of all images on popular home pages have poor or missing alternative text.

Think about that for a moment. If your WordPress site has 300 images, roughly 60 of them might be doing absolutely nothing for your search visibility. They’re dead weight, optimized for speed, perhaps, but invisible to Google.

Why nobody fills out alt text (and why it’s not your fault)

Let’s be honest: writing alt text is tedious.

You upload an image. WordPress prompts you for alt text. You think, “I’ll do it later.” Then you forget. Or you write something generic like “image” or “photo” because you’re in a hurry. Or you copy-paste the filename, which reads like “IMG_4829.jpg.”

Multiply this by hundreds or thousands of images, and you see the problem.

For site owners managing large media libraries, the task is overwhelming:

• E-commerce sites with thousands of product images
• Photography portfolios with hundreds of gallery images
• Blogs and publishers with years of archived content
• Corporate sites that have changed hands multiple times

Going back and manually writing unique, descriptive alt text for every single image? That could take weeks. Most people never do it.

Why missing alt text is costing you traffic

Alt text isn’t just an accessibility nice-to-have (though it absolutely matters for users with screen readers). It’s how search engines “see” your images.

Without descriptive alt text, Google has no idea what your image shows. That means:

❌ Your images won’t appear in Google Image Search (which drives 22.6% of all web searches)

❌ Your pages miss out on contextual relevance signals that boost overall rankings

❌ You’re leaving opportunities on the table for long-tail keyword variations

❌ Your site accessibility scores suffer, which can indirectly impact SEO

The data backs this up. WebAIM’s research shows that while the percentage has slowly improved from 23.2% in 2022 to 18.5% in 2025, we’re still talking about millions of images across the web that are essentially wasted SEO opportunities.

Automated alt text that actually works

This is where AI changes the game completely.

Modern AI can analyze an image, understand what’s in it, and generate contextually relevant alt text in seconds. Not generic placeholders—actual descriptions that help both users and search engines.

ShortPixel’s new AI Image SEO features (introduced in version 6.3.0) do exactly this, and it’s built directly into the WordPress plugin you might already be using for image optimization.

Here’s how it works:

1. Enable AI Image SEO in your settings

Go to Settings > ShortPixel > AI Image SEO and turn on the feature. You now have access to automated SEO generation across your entire site.

2. Automatic generation on upload

Every time you upload a new image, ShortPixel’s AI immediately generates alt text, captions, and descriptions. No extra steps. No manual typing. Just upload images as usual.

3. Bulk process your existing library

Already have thousands of images without proper alt text? Run bulk processing through Media > Bulk ShortPixel, and the AI will retroactively generate SEO data for your entire media library.

If you’ve already added alt text to your images, you can optionally enable the option to preserve it and prevent it from being overwritten.

4. Context-aware descriptions

This is where it gets smart. You can provide the AI with context about your website, niche, brand, focus, and it adapts its output accordingly.

For example, if you run a fitness blog, an image of someone running won’t just get “person running.” It might get “runner performing interval training on outdoor track” because you provide the AI with additional details to understand your site’s context.

You can even enable parent page/post title integration, so the AI uses the title of the page or post where the image appears to make descriptions even more relevant. Also, you can select the language for the image SEO data.

6. Preview before applying

Not sure if you trust AI yet? Use preview mode to see what the AI generates before applying it across your site.

What happens when you fix your image SEO

Let’s talk results.

When you properly optimize your images with descriptive alt text:

✅ Google will index your images for Image Search, opening up a new traffic channel. You can monitor Search Console for results.

✅ Your pages gain semantic relevance through additional contextual signals. For example, if you upload a photo of a red leather handbag and only name the file, Google won’t know much about it. But if the image also has descriptive alt text, a short caption, and sits in a page where the text talks about handbags and accessories, all those details give Google extra context. That context makes the photo, and the whole page, more relevant for searches about handbags.

✅ You rank for more long-tail variations because each image adds descriptive content. A page about hiking boots that includes an image tagged “waterproof hiking boots for snow” might start showing up for that longer search, even if the exact phrase isn’t in your main text. Each image basically adds more descriptive language, which helps your page rank for a wider range of long-tail searches.

✅ Your site becomes more accessible, improving user experience for everyone.

✅ You save hours or days of manual work.

And because ShortPixel already handles image compression and optimization, you’re getting the complete package: images that load fast and rank well.

The bottom line: Stop leaving SEO on the table

Nearly 20% of images on the web are invisible to search engines. If your site is part of that statistic, you’re working harder than you need to while getting worse results.

The good news? Fixing this doesn’t require hiring an SEO expert or spending weeks manually updating your media library.

With AI-powered image SEO built right into ShortPixel Image Optimizer, you can:

• Fix your entire existing library in one bulk operation
• Automatically handle all new uploads going forward
• Customize the output to match your site and brand
• Generate alt text, captions, and descriptions in seconds

Your images are already on your site. Make them work for you.