Automated particle tracking. (a) Processed image of tray 1 at the beginning of a shaking cycle. (b) Same image as in (a), binarized. (c) Binarized image of tray 1 at the end of a shaking cycle with the detected particles (purple circles) and tracks (colored lines) superposed. The track colors indicate the point in time during the shaking cycle: bluer colors indicate that the track was detected earlier during the shaking cycle while redder colors indicate later detections.