This is intended for [eye] doctors to use as a portable vision/eye test chart. It displays 1 random letter at a time at industry standard sizes for a patient to read for visual acuity testing purposes.Only tested on Motorola Droid. Please submit bugs/requests!There is also a free version available (has disabled options)Features: *Multiple image sets (Limited on free version) *Multiple ways to move through/choose images *Set image size (Adjustable by "viewer distance"). Calibration screen is also provided. *Configurable actions (Limited on free version) *Invert colors *Full screen (Limited on free version)See website (below) for much more information.