Corona draws an image on top of a black background. I believe we use a 1536x1536 or so. If your image is smaller than the screen size, there will be a black background behind it.
If you need something other than a black background, I would disable the splash screen and show your own screen in main.lua where you can control the default background color to match your screen and then show as small of an image that you need to achieve the logo you want to display.
Corona draws an image on top of a black background. I believe we use a 1536x1536 or so. If your image is smaller than the screen size, there will be a black background behind it.
If you need something other than a black background, I would disable the splash screen and show your own screen in main.lua where you can control the default background color to match your screen and then show as small of an image that you need to achieve the logo you want to display.