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(a, b) The raw CMOS sensor image (a) and image merged with a pattern mask to be divided into uniform blocks (b) were processed by threshold adjustment and size extraction. (c, d) The shadow patterns were extracted from the raw image (c) and the masked image (d). Figures in red within (c, d) indicate the serial number of the extracted patterns. (e, f) Size histograms of the extracted shadow patterns were also generated.
