A thumbnail image is a smaller scale snapshot of your report. Thumbnails are useful for showing people a preview of the report's first page. Thumbnail images are stored in the cloud, so you can link to them with no need to download or upload.
How thumbnails work
To display a thumbnail, append the /thumbnail endpoint to the URL of your report. This will create a scaled image of the first page of that report. For example, here's the thumbnail URL for the Google Ads report template:
lookerstudio.google.com/reporting/0B5FF6JBKbNJxOWItcWo2SVVVeGc/page/DjD/thumbnail
The resulting thumbnail image shows the Google Ads report template.
Thumbnails are scaled to 320 px x 240 px. For long reports, the thumbnail will try to include the entire report page in those dimensions. For reports with a wide aspect ratio, such 16:9, the thumbnail will try to fit the entire height.
Update the thumbnail image
To generate a new thumbnail image, edit and then view the report.
Who can see the thumbnail?
Only people with View or Edit access to the report can see its thumbnail. In addition, any data sources for the report must be set to owner's or service account credentials. People without proper access see a default Looker Studio logo image instead.
You'll also see this icon for deleted reports.
Use the thumbnail image
You can use thumbnail images in web pages by providing the report's /thumbnail URL as the src parameter of the HTML <img> tag.
Troubleshooting thumbnails
Having trouble displaying a thumbnail image? Check the following:
Be sure you can view the report. Thumbnails are only available for reports you can see.
Edit the report, then view it again. This will generate a new thumbnail image.
All the data sources added to the report must use Owner's Credentials. Thumbnails can't be shown for reports whose data source uses Viewer's Credentials.