JPH04340687A - Optical pattern recognition device - Google Patents

Abstract

PURPOSE:To exactly recognize a pattern to be recognized even when a position for the center of gravity is deviated between the pattern to be recognized and a reference pattern. CONSTITUTION:This device is equipped with an optical filter 31 to obtain the power spectrum of the reference pattern by executing Fourier transformation after logarithmic transformation, Fourier transformation optical systems 22, 23 and 25 to execute the Fourier transformation of pattern light to be recognized, radiation optical systems 30, 32 and 33 to radiate the optical filter with the Fourier spectrums of these Fourier transformation optical systems after logarithmic transformation and Fourier transformation, and recognition processing means 40 to recognize the pattern to be recognized according to an optical correlation signal between the reference pattern, which is generated at the optical filter by this irradiation due to the radiation optical systems, and the pattern to be recognized, and to calculate the size deviation of the pattern to be recognized to the reference pattern.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pattern recognition device that performs pattern recognition using optical correlation.

0002

2. Description of the Related Art In such a recognition device, a matched filter is first created. FIG. 7 is a block diagram of a matched filter creation device. The laser beam output from the laser oscillator 1 is split into two directions by the beam splitter 2, and one of the laser beams is reflected by each mirror 3 and 4, and the beam diameter is expanded by the expanding collimator system 5 and sent to the dry plate as a reference beam. 6 at a predetermined angle. The beam diameter of the other laser beam that is branched at the same time is expanded by an enlarging collimator system 7, passes through a reference pattern mask 8, is Fourier transformed by a Fourier transform lens 9, and is irradiated onto a dry plate 6. As a result, a Fourier spectrum of the reference pattern is generated on the dry plate 6 and written on the dry plate 6. Then, a plurality of reference patterns are written on the dry plate 6 by changing the incident angle of the reference light onto the dry plate 6. This dry plate 6 is developed and becomes a matched filter.

Next, pattern recognition is performed using the configuration shown in FIG. The beam diameter of the laser beam output from the laser oscillator 1 is expanded by the expanding collimator system 10, and the beam diameter is irradiated onto the pattern mask 11 to be recognized. The laser beam transmitted through this recognition pattern mask 11 is transmitted through the Fourier transform lens 1
2 and is then subjected to Fourier transformation and is applied to a matched filter 6. As a result, correlation between the reference pattern and the pattern to be recognized is performed, and if the pattern to be recognized is the same as the reference pattern, the light is diffracted in the direction of the reference light, and the camera 13 is disposed in this direction.

0004

However, in such pattern recognition, if the centroid positions of the recognized pattern and the reference pattern are shifted, the recognized pattern cannot be accurately recognized.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide an optical pattern recognition apparatus that can accurately recognize a pattern to be recognized even if the center of gravity of the pattern to be recognized and the reference pattern are shifted.

[0006]

[Means for Solving the Problems] The present invention provides an optical filter obtained by logarithmically transforming the power spectrum of a reference pattern and then performing Fourier transform, a Fourier transform optical system that performs Fourier transform of pattern light to be recognized, and An irradiation optical system that logarithmically converts and Fourier transforms the power spectrum obtained by imaging the Fourier spectrum of the conversion optical system and irradiates the optical filter, and a reference pattern and a target pattern generated on the optical filter by the irradiation of the irradiation optical system. The present invention is an optical pattern recognition device that attempts to achieve the above-mentioned object by including a recognition processing means that recognizes a recognized pattern from an optical correlation signal with the pattern and determines a size deviation of the recognized pattern with respect to a reference pattern. .

The present invention also provides an optical filter obtained by polar coordinate transformation and Fourier transformation of the power spectrum of a reference pattern, a Fourier transformation optical system for Fourier transformation of pattern light to be recognized, and a Fourier transformation optical filter of the Fourier transformation optical system. An irradiation optical system that polar coordinates and Fourier transforms the power spectrum obtained by imaging the spectrum with an imaging device and irradiates the optical filter, and an optical system that connects the reference pattern and recognized pattern that are generated on the optical filter by the irradiation of this irradiation optical system. The present invention is an optical pattern recognition apparatus that attempts to achieve the above object by including a recognition processing means that recognizes a recognized pattern from a correlation signal and determines a deviation such as an inclination of the recognized pattern with respect to a reference pattern.

The present invention also provides an optical filter obtained by performing polar coordinate transformation and logarithmic transformation of the power spectrum of a reference pattern, followed by Fourier transformation, and a Fourier transformation optical system that Fourier transforms the pattern light to be recognized. An irradiation optical system converts the Fourier spectrum of the Fourier transform optical system into a power spectrum obtained by imaging with an imaging device, performs polar coordinate transformation, logarithm transformation, and then performs Fourier transformation to irradiate the optical filter. The above object is achieved by providing recognition processing means for recognizing the recognized pattern from an optical correlation signal between the reference pattern and the recognized pattern generated in the process, and for determining deviations such as inclination of the recognized pattern with respect to the reference pattern. It is an optical pattern recognition device.

[0009]

[Operation] By providing such a means, when using an optical filter obtained by performing Fourier transformation after logarithmically transforming the power spectrum of the reference pattern, the light of the pattern to be recognized can be Fourier transformed by the Fourier transformation optical system. The resulting Fourier spectrum is imaged by an imaging device, the power spectrum is logarithmically converted, Fourier-transformed by an illumination optical system, and irradiated onto an optical filter. This irradiation produces an optical difference between the reference pattern and the recognized pattern on the optical filter. The recognition processing means recognizes the pattern to be recognized from the correlation signal and determines the deviation in size of the pattern to be recognized from the reference pattern.

[0010] Furthermore, when using an optical filter obtained by polar coordinate transformation and Fourier transformation of the power spectrum of the reference pattern, the power spectrum obtained by imaging the Fourier spectrum obtained by Fourier transformation of the recognized pattern light with an imaging device is used. It undergoes polar coordinate transformation, Fourier transformation, and irradiation to an optical filter. As a result, the deviation, such as the inclination, of the recognized pattern with respect to the reference pattern is determined.

Furthermore, when using an optical filter obtained by subjecting the power spectrum of the reference pattern to polar coordinate transformation and logarithmic transformation, and then Fourier transformation, the power spectrum of the reference pattern can be obtained by imaging the Fourier spectrum of the pattern light with an imaging device. The resulting power spectrum is polar coordinate transformed, logarithmically transformed, and then Fourier transformed and irradiated onto an optical filter. As a result, the deviation, such as the inclination, of the recognized pattern with respect to the reference pattern is determined.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an optical pattern recognition device. Below the CCD camera 20 is a pattern 21 to be recognized.
is placed. A monitor television 22 is connected to an image output terminal of this CCD camera 20. A spatial light modulator 23 is arranged in front of the screen of this monitor television 22. This spatial light modulator 23 writes the image displayed on the monitor television 22, and reads out the written image by the incidence of laser light. A Fourier transform lens 2 is connected to the image output side of the spatial light modulator 23 via a polarizing beam splitter 24.
5 is arranged, and a CCD camera 26 is arranged at the focal position of this Fourier transform lens 25.

An image output terminal of this CCD camera 26 is connected to an image processing device 30. This image processing device 3
0 has the following functions. That is, the image processing device 30 has a function of storing a plurality of reference patterns and sending the reference patterns to the liquid crystal display device 31. By sending the reference pattern to the liquid crystal display device 31 and displaying it in this manner, the liquid crystal display device 31 functions as an optical filter. Here, creation of the reference pattern will be explained.

A reference pattern image g(x
, y) are imaged, and this reference pattern image is sent to an image processing device. This image processing device uses a reference pattern g(x
, y) to obtain the square of its absolute value, that is, the power spectrum |F{g(x,y)}|2=G(u,v), and then perform logarithmic transformation to obtain G Find '(u', v'). Here, u'=logu, v'=logv. Then, the image processing device performs Fourier transform on G'(u', v') to obtain g'(x, y).

[0016] This g'(x, y) includes an amplitude term and a phase term. Therefore, g'(x, y) is divided by the absolute value of the amplitude term to obtain only the phase term, and this phase term is converted to g'PO
It is expressed as Then, g'PO is binarized under the following conditions. g'PO=1 (g'PO≧0) g'PO=0 (g'PO<0) However, the binarized information g'BPO is stored in the image processing device 30 as a reference pattern.

The image processing device 30 also includes a CCD camera 26.
It has a function of logarithmically converting the power spectrum of the recognized pattern 21 imaged by and sending it to the monitor television 32. A spatial light modulator 33 is arranged in front of the screen of this monitor television 32, and this spatial light modulator 23
A Fourier transform lens 35 is arranged on the image output side of the image forming apparatus with a polarizing beam splitter 34 interposed therebetween. The liquid crystal display device 31 is placed at the focal point of the Fourier transform lens 35. An inverse Fourier transform lens 36 is provided at a position opposite to the Fourier transform lens 35 via this liquid crystal display device 31.
are arranged, and further a CCD camera 37 is arranged.

A laser oscillator 38 is also provided, and an enlarged collimator system 39 is disposed on the laser output optical path of the laser oscillator 38. And the expansion collimator system 39
The laser beam having an expanded diameter is transmitted to the polarizing beam splitter 34 and the polarizing beam splitter 24.

The image output terminal of the CCD camera 37 is connected to a recognition processing device 40 . This recognition processing device 4
0 determines the position of the diffracted light from the image signal from the CCD camera 37, recognizes the pattern of the recognized pattern 21 from this position, and displays this image data on the monitor television 41.
It has a function to send to. In this case, the size deviation of the recognized pattern 21 with respect to the reference pattern is displayed on the monitor television 41 as a positional deviation. That is, if the recognized pattern 21 is shifted by a times in the x direction and b times in the y direction with respect to the reference pattern, the diffracted light will be displayed at the position (loga, logb) in the displayed xy logarithmic coordinates. . Next, the operation of the apparatus configured as described above will be explained with reference to the drawings.

[0020] The CCD camera 20 images the pattern to be recognized 21 and outputs the image signal. This image signal is sent to a monitor television 22, and the recognized pattern 21 is displayed on the monitor television 22. As a result, the image of the recognized pattern 21 displayed on the monitor television 22 is written into the spatial light modulator 23 .

At this time, when the laser beam output from the laser oscillator 37 enters the spatial light modulator 23 via the polarizing beam splitter 24, the recognition pattern image written in the spatial light modulator 23 is read out. This pattern image to be recognized passes through the polarizing beam splitter 24, undergoes Fourier transformation by the Fourier transformation lens 25, and enters the CCD camera 26. This CCD camera 26 images a Fourier spectrum and outputs the image signal. and,
This image signal is sent to the image processing device 30.

On the other hand, the image processing device 30 reads out a pre-stored reference pattern and sends it to the liquid crystal display device 31. Thereby, the liquid crystal display device 31 functions as a filter for the reference pattern.

In this state, the image processing device 30 receives the image signal from the CCD camera 26, stores it as image data, performs logarithmic transformation on this image data, that is, the power spectrum of the pattern to be recognized 21, and displays it on the monitor television 32. send to A logarithmically converted image is displayed on the monitor television 32, and this image is transmitted to the spatial light modulator 3.
Written in 3. At this time, when the laser beam output from the laser oscillator 38 enters the spatial light modulator 33 via the polarization beam splitter 34, the spatial light modulator 33
The image written on is read out, transmitted through the polarizing beam splitter 34, subjected to Fourier transformation by the Fourier transformation lens 35, and irradiated onto the liquid crystal display device 31.

By this irradiation, an optical correlation between the reference pattern and the pattern to be recognized 21 can be obtained. This optical correlation is imaged by the CCD camera 37, and the image signal is sent to the recognition processing device 40.

This recognition processing device 40 is a CCD camera 37.
The position of the diffracted light is determined from the image signal from the image signal, the pattern of the recognized pattern 21 is recognized from this position, and this image data is sent to the monitor television 41. This results in
The size deviation of the recognized pattern 21 with respect to the reference pattern is displayed on the monitor television 41 as a positional deviation. For example, FIG. 2 shows a correlation signal when the sizes of the recognized pattern and the reference pattern are the same, and FIG. 3 shows the correlation signal when the recognized pattern 21 is a times the reference pattern in the x direction and b times in the y direction. Indicates a case where there is a deviation. That is, in xy logarithmic coordinates (loga, logb)
The diffracted light is displayed at the position.

As described above, in the first embodiment, the light of the pattern to be recognized is Fourier-transformed into a Fourier spectrum, and the power spectrum obtained by imaging this Fourier spectrum with the CCD camera 26 is converted into a logarithm by the image processing device 30. Convert and send the image to optical filter 3
1, the pattern to be recognized 21 can be accurately recognized even if the center of gravity of the pattern to be recognized 21 is shifted from the reference pattern. Further, the recognition processing device 40 recognizes the recognized pattern 21 from an optical correlation signal between the reference pattern and the recognized pattern 21 generated in the optical filter 31, and determines the size deviation of the recognized pattern 21 with respect to the reference pattern. , the size of the recognized pattern 21 is a times the size of the reference pattern in the x direction, and the size of the recognized pattern 21 is
Even if the pattern is multiplied by b in the direction, the pattern to be recognized 21 can be recognized, and the size deviation of the pattern to be recognized 21 from the reference pattern can be determined. Furthermore, since it is optical pattern recognition, pattern recognition can be done instantly. Next, a second embodiment of the present invention will be described. Note that the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted. Figure 4
1 is a configuration diagram of an optical pattern recognition device.

The image processing device 50 has the following functions. That is, this image processing device 50 has a function of storing a plurality of reference patterns and sending the reference patterns to the liquid crystal display device 31. An optical filter is formed by sending the reference pattern to the liquid crystal display device 31 and displaying it in this manner. Here, creation of the reference pattern will be explained.

A reference pattern image g(x
, y) are imaged, and this reference pattern image is sent to the image processing device. This image processing device uses a reference pattern g(x
, y) to obtain the square of its absolute value, that is, the power spectrum |F{g(x,y)}|2=G(u,v). Note that F represents Fourier transform. Next, polar coordinate transformation and logarithmic transformation are performed to obtain G'(θ, r). Here, r= log(u2+v2)1/2, θ= tan-1
(v/u). Then, the image processing device G′(θ,
r) is Fourier transformed to find g'(u,v).

This g'(u,v) includes an amplitude term and a phase term. Therefore, g′(u,v) is divided by the absolute value of the amplitude term to obtain only the phase term, and this phase term is converted into g′PO
It is expressed as Then, g'PO is binarized under the following conditions. g'PO=1 (g'PO≧0) g'PO=0 (g'PO<0) However, the binarized information g'BPO is stored in the image processing device 50 as a reference pattern.

The image processing device 50 also includes a CCD camera 26.
It has a function of obtaining a power spectrum from the Fourier spectrum of the pattern to be recognized 21 imaged by , converting it into polar coordinates and logarithmically, and sending it to the monitor television 32 .

The recognition processing device 51 also includes a CCD camera 37.
The position of the diffracted light is determined from the image signal from the image signal, the pattern of the recognized pattern 21 is recognized from this position, and the position of the diffracted light is sent to the monitor television 41. In this case, the similarity and rotation angle of the recognized pattern 21 with respect to the reference pattern are displayed on the monitor television 41 as a positional deviation. That is, if the recognized pattern 21 is shifted by c times in the x and y directions with respect to the reference pattern and is tilted by the inclination θ, the diffracted light will be displayed at the position (θ, logc). Next, the operation of the apparatus configured as described above will be explained. When the CCD camera 20 images the pattern to be recognized 21, the image signal is displayed on the monitor television 22, and this image is written into the spatial light modulator 23.

At this time, when the laser beam enters the spatial light modulator 23, the pattern image to be recognized written on the spatial light modulator 23 is read out, subjected to Fourier transformation by the Fourier transformation lens 25, and sent to the CCD camera 26. incident. This CCD camera 26 images a Fourier spectrum and outputs the image signal. On the other hand, the liquid crystal display device 31 functions as a filter for the reference pattern.

In this state, the image processing device 50 receives the image signal from the CCD camera 26, performs polar coordinate transformation and logarithmic transformation on the power spectrum of the recognized pattern 21, and sends it to the monitor television 32. The image displayed on the monitor television 32 is written to the spatial light modulator 33, and this image is read out by laser beam incidence.
The light is Fourier transformed by the Fourier transform lens 35 and irradiated onto the liquid crystal display device 31 .

By this irradiation, an optical correlation between the reference pattern and the pattern to be recognized 21 can be obtained. This optical correlation is imaged by the CCD camera 37, and the image signal is sent to the recognition processing device 51.

This recognition processing device 51 is a CCD camera 37.
The position of the diffracted light is determined from the image signal from the image signal, the pattern of the recognized pattern 21 is recognized from this position, and this image data is sent to the monitor television 41. This results in
The size deviation of the recognized pattern 21 with respect to the reference pattern is displayed on the monitor television 41 as a positional deviation. For example, FIG. 5 shows a correlation signal when the size of the recognized pattern and the reference pattern are the same and there is no inclination, and FIG. In addition, the case where the slope is θ is shown.

As described above, in the second embodiment, even if the center of gravity of the recognized pattern 21 is shifted from the reference pattern, as in the first embodiment, the recognized pattern 21
can be accurately recognized, and in addition, it is possible to determine the deviation of the recognized pattern 21 from the reference pattern by a factor of c in the x and y directions, that is, the degree of similarity and the inclination θ. Next, the third aspect of the present invention
An example will be explained.

In this embodiment, the optical filter 31 obtained by polar coordinate transformation of the power spectrum of the reference pattern and then Fourier transformation is used, and the image processing device receives the image signal from the CCD camera 26 It has a function of converting the power spectrum of the pattern light to be recognized into polar coordinates and sending it to the monitor television 32.

With such a configuration, even if the center of gravity of the recognized pattern 21 is shifted from the reference pattern, the recognized pattern 21 can be accurately recognized, as in the first embodiment, and the recognized pattern 21 can be accurately recognized. It goes without saying that the slope θ with respect to the reference pattern No. 21 can be determined.

It should be noted that the present invention is not limited to the above embodiments, and may be modified without changing the gist thereof. For example, the spatial light modulator may be one that obtains a coherent image, such as an MSLM or a liquid crystal light valve, and the phase conjugate mirror may be one that is a nonlinear crystal such as BSO or KTP.

[0040]

As described in detail above, according to the present invention, it is possible to provide an optical pattern recognition apparatus that can accurately recognize a pattern to be recognized even if the center of gravity of the pattern to be recognized and the reference pattern are shifted.

[Brief explanation of drawings]

FIG. 1: A first optical pattern recognition device according to the present invention.
FIG. 2 is a configuration diagram showing an example.

FIG. 2 is a diagram showing the position of diffracted light displayed on the device.

FIG. 3 is a diagram showing the position of diffracted light displayed on the device.

FIG. 4: A second optical pattern recognition device according to the present invention.
FIG. 2 is a configuration diagram showing an example.

FIG. 5 is a diagram showing the position of diffracted light displayed on the device.

FIG. 6 is a diagram showing the position of diffracted light displayed on the device.

FIG. 7 is a configuration diagram of a conventional matched filter creation device.

FIG. 8 is a configuration diagram of a conventional optical pattern recognition device.

[Explanation of symbols]

20, 26, 37... CCD camera, 21... Recognized pattern, 22, 32, 41... Monitor television, 23, 3
3... Spatial light modulator, 24, 34... Polarizing beam splitter, 25, 35... Fourier transform lens, 30, 50... Image processing device, 31... Liquid crystal display device, 36... Inverse Fourier transform lens, 38... Laser oscillator, 39 ...Enlarged collimator system, 40...Recognition processing device.

Claims (3)

[Claims] 1. An optical filter obtained by performing Fourier transformation after logarithmically transforming the power spectrum of a reference pattern, a Fourier transformation optical system that Fourier transforms the recognized pattern light, and a Fourier transformation optical system that transforms the Fourier spectrum of this Fourier transformation optical system into a logarithm. An irradiation optical system that performs Fourier transformation and irradiates the optical filter, and an optical correlation signal between the reference pattern and the recognition pattern that is generated on the optical filter by the irradiation of the irradiation optical system, and the recognized pattern is detected. 1. An optical pattern recognition apparatus comprising: recognition processing means for recognizing and determining a size deviation of the recognized pattern with respect to the reference pattern. 2. An optical filter obtained by polar coordinate transformation and Fourier transformation of the power spectrum of a reference pattern;
a Fourier transform optical system that Fourier transforms the pattern light to be recognized; an irradiation optical system that performs polar coordinate transformation and Fourier transform on the Fourier spectrum of the Fourier transform optical system and irradiates the optical filter; The present invention is characterized by comprising recognition processing means for recognizing the to-be-recognized pattern from an optical correlation signal between the reference pattern and the to-be-recognized pattern generated in a filter and determining the inclination of the to-be-recognized pattern with respect to the reference pattern. optical pattern recognition device. 3. An optical filter obtained by subjecting the power spectrum of a reference pattern to polar coordinate transformation and logarithmic transformation, followed by Fourier transformation, a Fourier transformation optical system that Fourier transforms the pattern light to be recognized, and the Fourier transformation optical system. an irradiation optical system that polar coordinates transforms the Fourier spectrum of the system, logarithmically transforms it, and then performs the Fourier transform to irradiate the optical filter; and the reference pattern and the recognized pattern that are generated on the optical filter by the irradiation of the irradiation optical system. An optical pattern recognition apparatus characterized by comprising a recognition processing means for recognizing the recognized pattern from an optical correlation signal and determining a deviation such as an inclination of the recognized pattern with respect to the reference pattern.