This is a quick and easy way to download dashboards as images I'd like to share. It's using Chrome's ability to capture 'full size' screenshots, which allows you to set the screen resolution yourself, and potentially optimize it for different devices.
Looker Presentation mode
Looker has the embed functionality, that can be used for private or public embedding, but there's a lesser known brother of this as well: presentation mode.
To see how these two modes compare, simply add either embed or presentation to your URL. For example, instead of
/presentation/dashboards/3. This will give you just the dashboard, without the Looker UI.
Looker in presentation mode:
Chrome full page screenshotting
Since Chrome 59, there's the option to take a screenshot of a full page, using the developer tools. This allows you to simulate certain device screen sizes or set a custom screen resolution and view the page at that resolution. Looker's dashboards are responsive, so they scale with the resolution of the screen.
To open developer tools
Setting the resolution & getting the screenshot
Once you've opened the dev console, You'll see a little icon on the top bar of the console. Click it and you'll see a bar on top with a device dropdown and a resolution picker. Now, on the same Device Toolbar on the right, hit the menu and select capture full size screenshot.
If you're into infographs and that sort of thing, you can make a quick one that looks like the one below. This one is a full size screenshot at the resolution of an iPhone 7 (see the full size example here).