For background image resolution, we send camera video with an aspect ratio of 1280x720 Pixels at maximum, and we will crop the background image in the center to fit the aspect ratio for both landscape and portrait images. To get better video quality, the requirement for the background image is:

• Landscape image: 1280x720 Pixels
• Portrait image: 1280x1920 Pixels

For image format, we support JPG/PNG/BMP, we do not support .GIF . To find the image format that supported by Android here:  https://developer.android.com/guide/topics/media/media-formats#image-formats