Clarity on image resolutions.
You have a few options here...
If don't want to provide all three resolutions, then use this:
This will automatically scale your images accordingly. The drawback of this method is that 720p images are upscaled to 1080p.
If you want to provide all resolutions, use this:
Regardless of the either method, you will still need to provide all 3 resolutions for your splash screen.