How to do SEO on images

Image SEO works through several interconnected signals that search engines use to understand and rank images. The most important factor is the filename itself—before you even upload an image, rename it to something descriptive using hyphens to separate words. Instead of "IMG_2847.jpg," use "blue-ceramic-coffee-mug-handmade.jpg." This gives search engines actual context about what they're looking at.

Alt text is equally critical and serves dual purposes. Write 100-125 characters describing what's in the image, focusing on the subject and context rather than keyword stuffing. For that coffee mug example, you might write "handmade blue ceramic coffee mug with handle on white background." This alt text helps Google understand the image while also improving accessibility for screen readers—search engines reward sites that serve users with disabilities. You should also use descriptive captions near images on your page, as Google analyzes surrounding text to understand image content. The image title tag (different from filename) can also include relevant information, though it's less important than alt text.

Technical implementation matters too. Compress images to reduce file size—large images slow down page speed, which affects rankings for the entire page. Use modern formats like WebP alongside traditional JPG/PNG to serve optimized versions to different browsers. Implement structured data markup using schema.org's ImageObject type, which helps Google understand what the image depicts and can increase visibility in Google Images and other rich snippets. For client websites, use descriptive heading tags and surrounding paragraph text that reinforces what the image shows.

Image context on the page significantly impacts ranking. An image of a hiking boot performs better on a hiking guide page than on a shoe review page. Similarly, images closer to relevant text receive more ranking benefit. For client work, ensure images are truly relevant to the content—don't just add stock photos for decoration.

Finally, build image authority by earning backlinks and citations for your images. When images appear on reputable sites with proper attribution, they gain more ranking power. For your own blog or portfolio, use images consistently and make them valuable enough that others want to feature them. This is why original photography and unique graphics often outrank generic stock photos in search results.