| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method of photographing a finger vein pattern with transmitted light with which the optimal quality of the vein pattern can be constantly obtained without being affected by the difference in an external environment.SOLUTION: A personal authentication device includes a light source that emits light transmitting through a finger, a photographing unit that photographs the light transmitted through the finger, finger detection means for detecting that the finger is present at a predetermined position, finger area extraction means for extracting an area occupied by the finger from the image photographed by the photographing unit, and gain changing means for changing the amplification factor of a photographing element in the photographing unit according to the image quality of a specific portion in the extracted area.</p> |
