To create alternative drawable bitmap for different densities, You Should follow the scaling ratio 3:4:6:8 Between the oven generalized densities. For example, if You Have a drawable bitmap that's 48x48 pixels for medium-density screen (the size for a launcher icon), all the different sizes Should Be:
36x36 for low-density (LDPI)
48x48 for medium-density (MDPI)
72x72 for high-density (HDPI)
96x96 for extra high-density (XHDPI)
144x144 for extra extra high-density (XXHDPI)
This is for Splash screen image size
- xlarge screens are at least 960dp x 720dp
- large screens are at least 640dp x 480dp
- normal screens are at least 470dp x 320dp
- small screens are at least 426dp x 320dp
More information on multiple screens here