Image analysis – Applications – Personnel identification
Reexamination Certificate
1999-11-19
2004-04-06
Au, Amelia M. (Department: 2623)
Image analysis
Applications
Personnel identification
C382S118000
Reexamination Certificate
active
06718050
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a face-image processing apparatus for determining opening/closing of the eyes in accordance with the multivalue face image of a person to be detected.
As a conventional face-image processing apparatus incorporating an illuminating means for irradiating the face of a person to be detected, an apparatus disclosed in the Unexamined Japanese Patent Application Publication No. Hei.9-198508 has been known.
FIG. 7
is a schematic view showing the structure of an conventional eye-state detecting apparatus disclosed in the Unexamined Japanese Patent Application Publication No. Hei.9-198508.
Referring to
FIG. 7
, reference numeral
1
represents a person to be detected,
2
represents a CCD camera for photographing the person
1
to be detected and
3
represents a multivalue image memory for storing the image photographed by the camera
2
. Reference numeral
4
represents a binarizing means for binarizing the multivalue image,
5
represents a binarized-image memory for storing the binarized image,
6
represents a binarized-image characteristic extracting means for extracting the characteristic from the binarized image and
7
represents an opening/closing determining means for determining opening/closing of the eyes in accordance with the characteristic of the binarized image. Reference numeral
8
represents an LED light source and
9
represents an LED operating circuit for passing an electric current to the LED light source
8
.
FIGS. 8A and 8B
show multivalue image of the face of a person to be detected and a binarized image reflected by the retina obtained by the apparatus disclosed in the Unexamined Japanese Patent Application Publication No. Hei.9-198508.
FIG. 8A
shows the multivalue image.
FIG. 8B
shows the binarized image.
Referring to
FIGS. 8A and 8B
, reference numeral
10
represents the multivalue image,
11
represents the binarized image,
14
represents the image reflected by the retina and
15
represents a binarized region of the image reflected by the retina.
When the face of the person
1
to be detected is photographed by the foregoing conventional face-image processing apparatus, the pupils of the person
1
to be detected are photographed as if the pupils glow owning to light reflected by the retinas of the eyeballs, as shown in FIG.
8
A. The reason for this lies in that the retinas have a characteristic which returns reflected light in the same direction as the direction of the incident light. The image
14
reflected by the retina is photographed with considerably intense brightness as compared with the other portions of the face. Therefore, a process for binarizing the overall portion of the photographed multivalue image enables a region having the intense brightness as shown in
FIG. 8B
to be extracted as a pupil region. In accordance with a fact whether or not the pupil region exists, that is, whether or not the binarized region
15
of the image reflected by the retina exists, the opening/closing state of the eyes is determined.
FIG. 9
shows a flow chart of an algorithm employed by the face-image processing apparatus disclosed in the Unexamined Japanese Patent Application Publication No. Hei.9-198508 for extracting the eyes.
An image of the face photographed in step S
1
is stored in the multivalue-image memory for one frame in step S
2
. A binarizing process is performed in step S
3
so that a multivalue image captured in step S
2
and output from the binarized-image memory is binarized by using a threshold value for binarization. A result of the binarizing process performed in step S
3
is stored in the binarized-image memory for one frame in step S
4
. In step S
5
an eye-candidate binarized region setting process is performed so that an eye candidate region is set from the binarized regions output from the binarized-image memory. In step S
6
the binarized eye region is selected from the eye candidate region set in step S
5
. If the binarized eye region is selected in step S
6
, opening/closing is determined in step S
7
such that an image reflected by the retina exists. That is, a determination is made that the eyes are opened. If the binarized eye region is not selected in step S
6
, opening/closing is determined in step S
7
such that no image reflected by the retina exists. That is, the eyes are closed.
As a conventional face-image processing apparatus using a template, an apparatus disclosed in, for example, the Unexamined Japanese Patent Application Publication No.
Hei.8-175218 is known. According to the foregoing disclosure, a driving state detecting apparatus has been disclosed which incorporates a template producing means for vertically and laterally moving a predetermined standard face template with respect to the photographed image to perform correlation calculations so as to produce an object template for the person to be detected; and an eye-region detecting means for detecting the eye region of the person to be detected by performing correlation calculations by using the object template.
FIG. 10
is a schematic view showing the structure of the driving state detecting apparatus disclosed in the Unexamined Japanese Patent Application Publication No. Hei.8-175218.
An image processing apparatus
17
is connected to a camera
2
for photographing a person
1
to be detected. An image of the face of the person
1
to be detected is supplied to the image processing apparatus
17
. The image processing apparatus
17
incorporates an A/D converter, a normalizing circuit and a correlation calculating circuit so as to convert the supplied image signal into a digital signal, followed by performing a process for normalizing light and shade. A memory
18
is connected to the image processing apparatus
17
. A standard template and layout data of elements of the face including the eyes and eyebrows are previously stored in the memory
18
. Moreover, an electronic control unit ,i.e., ECU
19
is connected to the image processing apparatus
17
so that a result of the process is supplied to the ECU
19
. The ECU
19
determines a state of driving of the person
1
to be detected in accordance with the result of the process. Thus, the ECU
19
outputs a control signal to an alarm unit
20
so that an alarm is issued.
As a conventional face-image processing apparatus using distribution of brightness, an apparatus disclosed in, for example, the Unexamined Japanese Patent Application Publication No. Hei.6-348980 is known. The foregoing apparatus is an apparatus which is capable of monitoring the eyes of a driver in a vehicle and structured to specify the positions of the eyes by paying attention to a fact that the black eye portions are the darkest portions in the frame. An average value of maximum and minimum brightness in the vicinity of the darkest point is used as the threshold value of the brightness so as to extract the eye region.
Specifically, a plurality of sampling points are determined at the positions of the eyes on the frame, and then each sampling point is shifted to the dark portion. In accordance with the sampling points converged to the black eye portions, the position of the eyes are specified. In accordance with the distribution of the brightness of the adjacent portions, the eye regions are extracted.
FIG. 11
is a diagram showing a process for extracting the eye regions which is performed by the apparatus disclosed in the Unexamined Japanese Patent Application Publication No. Hei.6-348980 and which uses the distribution of the brightness so as to monitor the eyes of the driver in the vehicle.
FIG. 11
shows a method with which mean brightness T_av of maximum brightness T (max) of portions adjacent to the eye and minimum brightness T (min) of the same is used as a threshold value so as to extract a black eye portion so that the width W of the eye is obtained.
The conventional apparatus which detects the state of the eyes by using an image reflected by the retinas incorporates the binarized-image characteristic extracting means
6
which binarizes a multivalue image
Au Amelia M.
LaRose Colin
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
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