Image SEO begins with a useful page and a meaningful image. Renaming a file or adding keywords cannot compensate for an irrelevant image, missing context or a poor user experience.
Make the image relevant to the page
Use an image that supports the surrounding content. Place it near the text it illustrates, write a short caption when a caption helps the reader, and avoid using a generic decorative image as the main visual for a specific topic.
Use descriptive filenames and alt text
A filename should identify the subject without becoming a list of keywords. Alt text should describe the information conveyed by the image for people who cannot see it. Decorative images can use an empty alt attribute when appropriate. Do not repeat the same keyword in every field.
Publish a technically usable image
Choose a supported format, provide a sensible intrinsic width and height, and serve an image close to the size required by the layout. Responsive images using `srcset` and `sizes` can let the browser select a more suitable candidate. Keep a normal `src` fallback when using `picture`.
Protect loading performance
Reserve space for images to reduce layout movement. Lazy-load images that are below the initial viewport, but do not blindly lazy-load the main image a visitor needs immediately. Measure the page with a performance tool after publishing changes.
Check the landing page
The page hosting the image should have a clear title, useful text and a coherent URL. Confirm that crawlers can discover the image through an HTML image element and that the page does not depend only on a CSS background image for important visual content.
An image publishing worksheet
Before publishing, write the page topic, image purpose, filename, alt text, displayed dimensions, intrinsic dimensions, format, loading behavior and source URL. This small record exposes common errors such as a generic filename, an alt text that repeats keywords, or an oversized image loaded into a small card.
What to inspect after publishing
Open the page on a narrow and wide viewport, inspect the image request in developer tools, and confirm that the image is visible without shifting the surrounding content. Check the rendered HTML for a useful `img` element, a fallback `src` when needed, and alt text that describes the image rather than the target keyword.
Acceptance details
A result is acceptable only when it meets the destination requirement, opens correctly and passes the visual or technical check described above. The output may be smaller, similar in size or larger than the source; record what actually happened instead of replacing the observation with a target percentage.
Sources and further reading
Google Search Central: Image SEO best practices covers discovery, responsive images, filenames and alt text. web.dev: Image performance covers sizing, loading and format choices.