In response to the last answer (not able to comment yet): The later versions of Android do not allow for a full screen size image, the image will appear in the middle of the screen with a background colour of your choosing. You can use a png if you like to make the image look nicer with colour and detail, but unfortunately you cannot have an image occupy the entire page. I find it's really buggy/hit and miss when making these changes also getting the compiler to recognise the changes.

Go for a company logo centre screen with your companies branding colour as your background.