Image resolution for mdpi, hdpi, xhdpi and xxhdpi
From a base image size, there is a 3:4:6:8:12:16 scaling ratio in drawable size by DPI.
LDPI – 0.75x
MDPI – Original size // means 1.0x here
HDPI – 1.5x
XHDPI – 2.0x
XXHDPI – 3x
XXXHDPI – 4.0x
For example, 100x100px image on a MDPI will be the same size of a 200x200px on a XHDPI screen.