A finger sensing device may include a finger sensing area to receive a user's finger moved in a sliding motion, and a controller cooperating with the finger sensing area for generating successive image samples at least some of which are separated by different time intervals. The controller may generate finger movement signals based upon the successive image samples and the different time intervals. The controller may generate a plurality of repeating groups of ratio-metrically related image samples based upon the different time intervals. The reduced number of image samples may provide greater processing efficiency and reduced power consumption.