| 摘要 |
PURPOSE:To shorten the time required for a thinning processing and to obtain an exact fingerprint picture by providing a mask composed of double areas, setting pre scribed threshold values to respective areas and painting out only one picture element in the pertinent spot of the picture when the number of black picture elements in a descending line is larger than the threshold value to the inside and the outside. CONSTITUTION:In the thinning processing to remove an unnecessary noise component from the fingerprint picture, the mask composed of the double inside and outside areas is provided in an almost rectangular or circular form and the binary picture of a fingerprint is scanned by the mask. In a state that the mask is arranged on the descending line(valley line), it is checked whether or not the number of the picture elements in the descending line(valley line) on the inside of the mask is more than a certain threshold value TH1 and the number of the picture elements in the descend ing line(valley part) is on the outside of the mask is more than a certain threshold value TH2. When the condition is satisfied, the correspondent spot of the separately prepared picture is painted out by the same value as the descending line(valley part) by one picture element. Thus, the time required for the thinning processing is shortened and further, the exact fingerprint picture can be obtained. |
