How Google Picks Image Thumbnails In Google Search & Google Discover

03/03/26
Source: Search Engine Roundtable by barry@rustybrick.com (Barry Schwartz). Read the original article

TL;DR Summary of Google’s Updated Image SEO Best Practices and Google Discover Guidelines

Google now uses schema.org markup and the og:image meta tag to determine preferred image thumbnails for Search and Discover. Webmasters can influence thumbnail selection by specifying relevant, high-resolution images following updated metadata guidelines. Recommended images should be large (at least 1200px wide), have a 16:9 aspect ratio, and avoid generic logos or text overlays. Proper cropping and positioning enhance image performance in Google Discover.

Optimixed’s Overview: Enhancing Your Website Visibility with Google’s Latest Image SEO and Discover Image Guidelines

Key Updates on Image Thumbnail Selection by Google

Google has refined its approach to selecting image thumbnails for Google Search and Discover by incorporating both schema.org markup and the og:image meta tag as authoritative sources. This update allows content creators to specify a preferred image more effectively, improving the chances of that image appearing as a thumbnail in search results and Discover feeds.

How to Specify Your Preferred Image

  • Use the schema.org primaryImageOfPage property with a direct URL or an ImageObject to indicate the main image.
  • Alternatively, assign an image URL or ImageObject to the main entity using mainEntity or mainEntityOfPage.
  • Set the og:image meta tag to specify a preferred image for social and search platforms.

Best Practices for Selecting Images

  • Choose images that are relevant and representative of the page content.
  • Avoid generic images such as site logos or images with embedded text in your schema.org markup or og:image tag.
  • Use images with a natural aspect ratio, steering clear of extreme narrow or overly wide formats.
  • Opt for high-resolution images, ideally at least 1200 pixels wide and around 300K pixels in size.

Google Discover Image Specifications

For enhanced visibility in Google Discover, Google recommends using compelling, large images that meet the following criteria:

  • Minimum width of 1200 pixels
  • High resolution (at least 300K pixels)
  • 16:9 aspect ratio to align with typical Discover image displays

Google attempts to automatically crop images for Discover, but if you manually crop images, ensure the key details remain visible and avoid forcing an aspect ratio that hides important content.

Summary

By following Google’s updated guidelines on image SEO and Discover content presentation, webmasters can significantly improve how their images appear across Google’s platforms. Proper use of schema.org markup and og:image tags combined with high-quality, well-cropped images ensures better control over thumbnail selection and potentially greater traffic via Google Discover.