Google uses both schema.org markup and the og:meta image tag for icons in Google Search and Discover

Google has updated both the image SEO best practices and the Google Discover help documentation to clarify that Google uses both the schema.org tag and the og:image meta tag as sources when determining image icons in Google Search and Discover.

Best practices for image SEO. Google has added a new section to the image SEO best help document called Specify image preferences with metadata. In that section, Google wrote:

• “Google’s selection of image previews is completely automatic and takes into account many different sources to choose which image on a given page is displayed on Google (for example, a text result image or a preview image in Discover).”
• Here’s how you influence the icons Google chooses:
  • Specify the schema.org primaryImageOfPage material with URL or ImageObject.
  • Or specify a picture URL or ImageObject property and attach it to the main entity (using schema.org mainEntity or mainEntityOfPage properties)
  • Specify i og:image meta mark.

Here are some general good practices when choosing these methods:

• Choose an image that is relevant and representative of the page.
• Avoid using a generic image (for example, your site logo) or an image with text in schema.org markup or og:image meta mark.
• Avoid using an image with an excessive aspect ratio (such as images that are too small or too wide).
• Use a higher resolution, if possible.

Google Discover image selection. In the Discover documentation Google added a section that reads:

• “Include compelling, high-quality images in your relevant content, especially large images that can generate Discover visits. We recommend using images that meet the following specifications: At least 1200 px wide, High resolution (at least 300K) and 16×9 aspect ratio”
• “Google tries to automatically crop an image for use in Discover. If you choose to crop your images yourself, make sure your images are properly cropped and positioned for space, and avoid using the default aspect ratio. For example, if you’re cropping a vertical image to a 16×9 aspect ratio, make sure important information is included in the cropped version you specify in the tag:)
• “Powered by the max-image-preview:large setup, or by using AMP“
• “Use schema.org markup or the og:meta image tag to specify a large image that is appropriate and representative of the web page, as this may affect which image is chosen as the icon in Discover. Learn more about how to specify the image you want. Avoid using generic images (for example, your site logo) in schema.org markups in schema.org in the image mevo or tag tag:. schema.org tag or og:image meta tag.”

Why do we care. Images can have a huge impact on click-through rates from both Google Search and Google Discover. Here, Google tells us ways we can encourage Google to choose a specific image for that icon. So review these help documents and see if any of this can help you with the images Google chooses for Search and Discover.