Systems for monitoring an inventory condition of objects based on captured images are described. An exemplary system includes at least one storage drawer, each storage drawer including a plurality of storage locations for storing objects; and a data storage device storing reference data for each storage drawer. The reference data includes, for each region of interest corresponding to each respective storage drawer, at least one of a reference image signature representing attributes of the region of interest when a stored object is present, and a reference image signature representing attributes of the region of interest when the stored object is not present. A data processor of the system is configured to derive an image signature representing attributes of a region of interest corresponding to a drawer using a captured image of the drawer; and determine an inventory condition of the drawer according to the stored reference data corresponding to the region of interest and the derived image signature representing attributes of the captured image of the region of interest.