Fig. 4

Handwritten digit recognition using a memristor-based RC system. a The process flow. The original digit image is first converted into pulse streams and fed to the memristor-based reservoir at different rates. The recognition result is generated after feeding the reservoir state to a trained readout function. b Some examples from the MNIST database. c Reservoir states corresponding to the three examples in b at two input rates (rate 1: timeframe width 0.8 ms, with pulse of 1.5 V, 0.5 ms; rate 2: timeframe width 4 ms, with pulses of 1.5 V, 0.8 ms), showing significant differences in the reservoir states. d False color confusion matrix showing the experimentally obtained classification results from the RC system vs. the desired outputs. The occurrence of the predicted output for each test case is represented by colors shown in the color scale. A recognition accuracy of 88.1% was obtained from the reservoir consisting of only 88 memristors