Google updated two Search Central documentation pages, adding guidance on how publishers can tell Google which image to prefer for thumbnails in Search results and Discover.
The company added a new section called “Specify a preferred image with metadata” to its Image SEO best practices page. It also updated the Discover documentation to reference the same metadata options.
On its documentation updates page, Google said the changes were made “based on feedback” to clarify that it uses both schema markup and the og:image meta tag when determining image thumbnails in Google Search and Discover.
What’s New
The new Image SEO section explains that Google’s image preview selection is automated and draws from multiple sources on a page. The updated docs explain how publishers can influence that selection through metadata.
Google listed three ways to specify a preferred image.
The first uses the schema.org primaryImageOfPage property on a WebPage type. The second attaches an image property to the page’s main entity using mainEntity or mainEntityOfPage. The third uses the og:image meta tag.
The documentation includes code examples for each method. For primaryImageOfPage, the structured data points to an image URL within a WebPage JSON-LD block. For the main entity method, the imageproperty goes inside a content type like BlogPosting. The og:image option uses a standard meta tag in the page’s HTML head.
Google also listed best practices for choosing the preferred image, saying you should pick an image that’s relevant and representative of the content. It says to avoid generic images like site logos and images containing text in the schema.org markup or og:image meta tag. Images that are too narrow or overly wide should also be avoided. High resolution is recommended when possible.
Discover Documentation Changes
The Discover page received a related update. Google added a recommendation to use either schema.org markup or the og:image meta tag to specify a large image for Discover thumbnails, and linked to the new Image SEO section for details.
Google says large image previews in Discover are enabled by the max-image-preview:large setting or AMP. The schema.org and og:image metadata can influence which image Google selects, but they don’t replace that eligibility requirement on their own.
The Discover documentation also added guidance about avoiding generic images and text-heavy images in the schema.org markup or og:image meta tag. These recommendations were already part of the existing Discover image guidance in a general sense, but the update connects them directly to the metadata methods.
This follows a broader revision to Discover documentation that Google made alongside the February Discover core update. That earlier revision rewrote recommendations around clickbait, page experience, and image quality. This documentation update builds on the image section of that same page.
Why This Matters
Google’s docs now spell out the metadata sources it may use when selecting a thumbnail for Search and Discover. The updated documents give you two specific methods to provide that signal: schema.org structured data and the og:image meta tag.
The existing recommendations call for images at least 1,200 pixels wide, high resolution (at least 300K), and 16×9 aspect ratio, and say large images are more likely to generate visits from Discover. The new metadata section explains how you can signal a preferred image that meets those specs, which can influence what gets chosen.
If you already use og:image tags or schema.org image properties, this update confirms that Google uses them. If you don’t, the documentation provides code examples to get started.
Looking Ahead
This document change is a clarification, not an update to how anything works.
Sites that want more control over which image appears in text result thumbnails can review the new section and check whether their existing markup aligns with Google’s recommendations.
