Finger identification method and apparatus
View Patent ↗An image pickup scheme capable of always providing an optimum quality of a blood vessel pattern, in image pickup of a blood vessel pattern of a finger using transmitted light, without being affected by a difference, if any, in an external environment. A personal identification apparatus includes light sources for irradiating light to be transmitted by a finger, an image pickup unit for picking up an image using light transmitted by the finger, finger detection unit for detecting that the finger exists in a predetermined position, finger region extraction unit for extracting a region occupied by the finger from an image picked up by the image pickup unit, and gain changing unit for changing an amplification factor of image pickup elements in the image pickup unit on the basis of a picture quality of a specific region within the extracted region.
1. A personal identification apparatus comprising:
an image pickup unit for picking up an image by using light transmitted by a finger; and
a processing unit for conducting personal identification by extracting blood vessels from an image picked up by said image pickup unit,
wherein:
said processing unit detects that the finger exists in a predetermined position, and extracts a region occupied by the finger from the picked up image, and
said processing unit controls a light source power control unit for changing power of light sources and/or a sensitivity control unit for changing an amplification factor of image pickup elements in said image pickup unit, on a basis of information in the extracted region.
2. The personal identification apparatus according to claim 1 , wherein:
said processing unit determines whether a quantity of light irradiated to the finger is within a predetermined range, on a basis of the information in the extracted region,
when the quantity of light irradiated to the finger is judged to be outside the predetermined range, said processing unit determines whether the quantity of light irradiated to the finger can be caused to be within the predetermined range by controlling the light source power control unit, and
when it is judged that the quantity of light irradiated to the finger cannot be caused to be within the predetermined range, said processing unit controls the sensitivity control unit.
3. The personal identification apparatus according to claim 2 , wherein:
when the quantity of light irradiated to the finger is judged to be larger than the predetermined range, said processing unit lowers power of the light sources via the light source power control unit, and
when the quantity of light irradiated to the finger is judged to be smaller than the predetermined range, said processing unit raises power of the light sources via the light source power control unit.
4. The personal identification apparatus according to claim 2 , wherein:
said processing unit detects existence of the finger on a basis of a change of the image picked up by a camera with time.
5. The personal identification apparatus according to claim 2 , further comprising an optical sensor,
wherein said processing unit calculates a gain value on a basis of a result of measurement conducted using said optical sensor, controls a sensitivity of said image pickup unit via the sensitivity control unit so as to attain the gain value, and conducts the finger detection.
6. The personal identification apparatus according to claim 1 , wherein:
when the quantity of light irradiated to the finger is judged to be larger than the predetermined range, said processing unit lowers power of the light sources via the light source power control unit, and
when the quantity of light irradiated to the finger is judged to be smaller than the predetermined range, said processing unit raises power of the light sources via the light source power control unit.
7. The personal identification apparatus according to claim 6 , wherein:
when the quantity of light irradiated to the finger is judged to be large even if the power of the light sources is minimized, or when the quantity of light irradiated to the finger is judged to be small even if the power of the light sources is maximized, said processing unit controls a sensitivity of said image pickup unit via the sensitivity control unit.
8. The personal identification apparatus according to claim 1 , wherein:
the light sources irradiate light to the finger alternately from left and right directions, and
said processing unit uses information in a partial region located on a side of light sources that are off, in the extracted region.
9. The personal identification apparatus according to claim 1 , wherein:
said processing unit detects existence of the finger on a basis of a change of the image picked up by a camera with time.
10. The personal identification apparatus according to claim 9 , further comprising an auxiliary light source,
wherein said processing unit detects existence of the finger on a basis of an image picked up using light irradiated by said auxiliary light source.
11. The personal identification apparatus according to claim 1 , further comprising an optical sensor,
wherein said processing unit calculates a gain value on a basis of a result of measurement conducted using said optical sensor, controls a sensitivity of said image pickup unit via the sensitivity control unit so as to attain the gain value, and conducts the finger detection.
12. The personal identification apparatus according to claim 1 , wherein:
an opening provided between the finger and the camera, and an opening of the camera are surrounded by a partition formed of smooth surfaces, and
other internal components are provided outside the partition.
13. The personal identification apparatus according to claim 1 , wherein:
the personal identification apparatus is attached to a part of an automobile, and
if the personal identification is successful, control of the automobile becomes possible.
14. A personal identification apparatus comprising:
a light source for irradiating light on a finger;
an image pickup unit for picking up an image of light transmitted by a finger under influence of external light, the light transmitted by the finger being produced by either said external light alone or a combination of said external light and the light irradiated by said light source; and
a processing unit for conducting personal identification by extracting blood vessels from the image picked up by said image pickup unit;
wherein said processing unit controls at least one of a light source power control unit for changing power of light sources and a sensitivity control unit for changing an amplification factor of image pickup elements in said image pickup unit, based on information of the image picked up by said image pickup unit.
15. A personal identification apparatus comprising:
a light source for irradiating light on a finger;
an image pickup unit for picking up an image of light transmitted by a finger under influence of external light, the light transmitted by the finger being produced by either said external light alone or a combination of said external light and the light irradiated by said light source;
a light source power control unit for changing power of said light source;
a sensitivity control unit for changing an amplification factor of image pickup elements in said image pickup; and
a processing unit for controlling said light source power control unit and said sensitivity control unit;
wherein said processing unit extracts blood vessels from the image picked up by said image pickup unit and controls at least one of said light source power control unit and said sensitivity control unit, based on information of said image.