The base size of a splash screen image represents the baseline density of the image, and is effectively the 1.0 scale factor for the image (the size you would typically use in your code to specify the splash screen size) from which all other sizes are derived. If you don't specify the base size for a bitmap image, the image isn't resized. If you don't specify a base size for a vector image, such as an SVG file, the dimensions specified in the image are used as the base size.
