| 摘要 |
PROBLEM TO BE SOLVED: To reproduce information by properly executing binarization. SOLUTION: A specific cycle in a dot code in a picture signal corresponding to the dot code is extracted by a cycle extracting part 12, and applied by field units through a detection gate 14 to a maximum value detecting part 15 and a minimum value detecting part 18. A binarization threshold is calculated from the detected maximum value and minimum value of field units by a threshold detecting part 20, and held in a data holding part 22. The held threshold is compared with the picture signal whose dot cycle is emphasized by a signal processing circuit 24 by a comparator 26 so that the picture signal corresponding to the dot code can be binarized. Also, a system control part 30 controls the illuminating light quantity of an LED 34 as a light source for illuminating the dot code based on the picture signal, and the threshold detecting part 20 changes the threshold to be calculated based on the change of the light quantity. |
