On a 10.1" Android tablet with a screen resolution of 12800x800, the image used in the splash screen is drawable-land-mdpi-screen.png, which nas a size of 480x320 pixels.

This also happens in tablets with higher screen resolution, although it is harder to see. For example, in a 2560x1600 tablet the image used is drawable-land-xhdpi-screen.png, which has a size of 1280x720.