For the background image, the format can be either PNG or JPEG. A resolution of 1920×1080 or above works best with a file size limit of 2MB. The background image appears on any of the Glisser generated slides, so on the polls and Q+A wall.
For the logo, we’d recommend no more than 800px x 800px, and to aim for less than 100kb (file size limit is also 2MB). Logos should also have a transparent background.
For additional information please see our guide on selecting a background image.