Driver monitoring apparatus, driver monitoring method, and program
A driver monitoring apparatus has a photographing means for taking a picture of a driver's face, an illumination means for emitting light to the driver's face, a light amount control means for setting the amount of light from the illumination means to a first or second amount of light, a differential image creating means for comparing image information about one image on which the driver's face to which the first amount of light was emitted is photographed with image information about another image on which the driver's face to which the second amount of light was emitted is photographed and then creating a differential image from differential information about brightness of corresponding pixels, a detecting means for detecting the driver's eyes from the differential image created by the differential image creating means, and a state detecting means for detecting the driver' state according to an image of the driver's eyes.
1. A driver monitoring apparatus comprising:
a photographing means for taking a picture of a face of a driver;
an illumination means for emitting light to the face of the driver;
a light amount control means for controlling an amount of light to be emitted from the illumination means so that the amount of light becomes a first amount of light or a second amount of light;
a differential image creating means for comparing image information about one image on which the face of the driver to which the first amount of light was emitted is photographed with image information about another image on which the face of the driver to which the second amount of light was emitted is photographed and then creating a differential image from differential information about brightness of corresponding pixels;
a detecting means for detecting eyes of the driver from the differential image created by the differential image creating means; and
a state detecting means for detecting a state of the driver according to an image of the eyes of the driver.
2. The driver monitoring apparatus according to claim 1 , wherein one of the first amount of light and the second amount of light is zero.
3. The driver monitoring apparatus according to claim 1 , further comprising a correcting means for correcting brightness in the differential image created by the differential image creating means, wherein
the detecting means detects the eyes of the driver from a differential image resulting from correction by the correcting means.
4. The driver monitoring apparatus according to claim 1 , wherein the light amount control means controls the amount of light to be emitted from the illumination means so that the amount of light becomes the first amount of light or the second amount of light in synchronization with a photographing timing taken by the photographing means.
5. The driver monitoring apparatus according to claim 1 , further comprising a brightness correcting means for creating pre-automatic-brightness-correction image information by subtracting an amount of correction for brightness that has been automatically corrected by the photographing means from brightness in image information obtained from the photographing means, wherein
the differential image creating means creates differential image information from the pre-automatic-brightness-correction image information.
6. The driver monitoring apparatus according to claim 1 , further comprising an image switching means for making a switchover to select image information to be supplied to the detecting means depending on illumination on an image of the face of the driver, wherein
if the image switching means decides that the illumination on the image of the face of the driver is lower than a predetermined threshold illumination, the image switching means supplies, to the detecting means, image information based on the differential image created by the differential image creating means,
if the image switching means decides that the illumination on the image of the face of the driver is higher than the predetermined threshold illumination, the image switching means supplies, to the detecting means, the image information obtained from the photographing means, and
the detecting means detects the eyes of the driver according to the supplied image information.
7. The driver monitoring apparatus according to claim 1 , wherein the state detecting means detects an orientation of the face of the driver.
8. The driver monitoring apparatus according to claim 1 , wherein the state detecting means detects an open/closed state of the eyes of the driver.
9. A driver monitoring method comprising:
a photographing step of taking a plurality of pictures of a face of a driver with different amounts of light emitted to the face of the driver;
a differential image creating step of comparing image information about one image on which the face of the driver to which a first amount of light was emitted is photographed with image information about another image on which the face of the driver to which a second amount of light was emitted is photographed and then creating a differential image from differential information about brightness of corresponding pixels;
a detecting step of detecting eyes of the driver from the differential image; and
a state detecting step of detecting a state of the driver according to an image of the eyes of the driver.
10. The driver monitoring method according to claim 9 , wherein one of the first amount of light and the second amount of light is zero.
11. The driver monitoring method according to claim 9 , further comprising a correcting step for correcting brightness in the differential image created by the differential image creating step, wherein
the detecting step detects the eyes of the driver from a differential image resulting from correction by the correcting step.
12. The driver monitoring method according to claim 9 , wherein the amount of light to be emitted becomes the first amount of light or the second amount of light in synchronization with a photographing timing in the photographing step.
13. The driver monitoring method according to claim 9 , further comprising a brightness correcting step for creating pre-automatic-brightness-correction image information by subtracting an amount of correction for brightness that has been automatically corrected by a photographing means from brightness in image information obtained from the photographing means, wherein
the differential image creating step creates differential image information from the pre-automatic-brightness-correction image information.
14. The driver monitoring method according to claim 9 , further comprising an image switching step for making a switchover to select image information to be supplied to the detecting step depending on illumination on an image of the face of the driver, wherein
if the image switching step decides that the illumination on the image of the face of the driver is lower than a predetermined threshold illumination, the image switching step supplies, to the detecting step, image information based on the differential image created by the differential image creating step,
if the image switching step decides that the illumination on the image of the face of the driver is higher than the predetermined threshold illumination, the image switching step supplies, to the detecting step, the image information obtained from the photographing step, and
the detecting step detects the eyes of the driver according to the supplied image information.
15. The driver monitoring method according to claim 9 , wherein the state detecting step detects an orientation of the face of the driver.
16. The driver monitoring method according to claim 9 , wherein the state detecting step detects an open/closed state of the eyes of the driver.
17. A program that causes a computer to function as:
a photographing means for taking a picture of a face of a driver;
an illumination means for emitting light to the face of the driver;
a light amount control means for controlling an amount of light to be emitted from the illumination means so that the amount of light becomes a first amount of light or a second amount of light;
a differential image creating means for comparing image information about one image on which the face of the driver to which the first amount of light was emitted is photographed with image information about another image on which the face of the driver to which the second amount of light was emitted is photographed and then creating a differential image from differential information about brightness of corresponding pixels;
a detecting means for detecting eyes of the driver from the differential image created by the differential image creating means; and
a state detecting means for detecting a state of the driver according to an image of the eyes of the driver.