According to one or more embodiments of the present invention, an image processing system includes a cross-point synapse array that includes multiple row wires, multiple column wires, and multiple cross-point devices, a cross-point device at each intersection of the row wires and the column wires. The image processing system further includes an image sensor array that includes multiple pixel unit circuits, each pixel unit circuit is connected to a corresponding row wire of the cross-point synapse array, wherein the pixel unit circuit generates a voltage output based on an input light. The image processing system further includes a pixel unit controller that adjusts an exposure time of the pixel unit circuits based on voltage outputs from the pixel unit circuits respectively.