JPH03204625A - Optical correlation processor - Google Patents

Abstract

PURPOSE:To increase the number of reference images by performing correlative arithmetic operation between a reference image and an image to be inspected through real-time operation without using a holography, etc., arranging a reference image group and the image to be inspected on mutual slanting optical axes, and then obtaining a composite Fourier transformed pattern. CONSTITUTION:The spatial patterns of the image to be inspected and reference image group which are displayed by image output means 1 and 3 are projected on the mutual slanting optical axes and processed by 1st and 2nd Fourier transforming means 2 and 4 by Fourier transformation. Those Fourier- transformed images are superimposed on a Fourier transformation surface to form multiple interference fringes between the reference image group and image to be inspected. At this time, a spatial frequency range to be compared is optimized by a spatial filter 6, the possible range of the multiple interference fringes is limited, and coherent luminous flux 77 having a phase distribution corresponding to the light intensity distribution of the multiple interference fringes is projected. Consequently, the number of the reference image group can be increased greatly and the utilization efficiency of an image display part can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical correlation processing device that can be used in the field of optical information processing. That is, the present invention relates to a calculation method and apparatus related to recognition and associative processing, particularly information processing in the optical measurement field and image processing field.

[Prior Art and Problems to be Solved by the Invention] Conventionally, there are a matched filter method and a joint transform method as methods for performing optical correlation calculations.

In the above-mentioned combined filter method, a two-dimensional reference image is Fourier-transformed, and then a reference wave is irradiated to create a new Fourier-transformed hologram, and the Fourier-transformed image of the test image is By superimposing
It was intended to perform correlation calculations.

The latter joint transform method records a Fourier transformed image of a composite of a test image and a reference image as an intensity pattern, and performs a correlation calculation by irradiating this with a plane wave.

However, in the former method, when recording the reference image,
It is necessary to change the irradiation direction of the reference wave for each image, making it difficult to process many images in real time.

On the other hand, in the latter method, the reference image and the test image can be presented simultaneously, making real-time processing possible, but when recording the intensity pattern of the composite Fourier transform image, In order to optimize the distance between the images and the distance between the images to be tested, the efficiency of using the image display section was poor. Also, if many reference images are presented, 1. ! - When the reference image on the Fourier transform plane is presented, the visibility of the multiple f interference fringes between the reference image and the test image on the Fourier transform plane becomes low.
It was difficult to present many reference images at once.

In addition, the present inventors introduced a feedback system that changes the amount of light irradiating the reference image based on the degree of correlation obtained by the latter method in the specifications of applications No. 4145.114146 and No. 1141S8. However, it was necessary to further increase the number of images to be tested.

The present invention was made in order to solve the problems mentioned above, and it is possible to easily create a reference image memory without using means such as holography, and it is possible to easily create a reference image memory with a group of reference images and a subject under test in real time. It is an object of the present invention to provide an optical correlation processing device that performs image correlation calculations, can dramatically increase the number of reference image groups, and improves the utilization efficiency of an image display section. That is, an object of the present invention is to provide a method for improving the multiplexing limit, which has been considered a drawback of the joint transform method.

[Means for Solving the Problems] Therefore, in order to solve the above technical problems, the present invention at least outputs a coherent image of a test image,
A first image output means (for example, 3) capable of temporally and spatially modulating the complex amplitude of output light electrically or optically, and a two-dimensional distribution of the complex amplitude of output light from the first image output means. A first optical Fourier transform means (for example, 4) that optically Fourier transforms the pattern, and a reference image on an optical axis that is inclined with respect to the optical axis of the light beam emitted from the first image output means. a second image output means (for example 1) capable of temporally and spatially modulating the complex amplitude of the output light electrically or optically, outputting a coherent image of the group; and an output from the second image output means. a second optical Fourier transformation means (for example 2) for optically Fourier transforming a two-dimensional distribution pattern of optical complex vibration; a Fourier transformation pattern obtained by the first optical Noricraft transformation means; A superimposing means (for example, 5) superimposes the Fourier transform patterns obtained by the second optical Fourier transform means, and the light receiving range of the Fourier transform patterns superimposed by the superimposing means is adjusted to the size of the test image. A spatial filter (for example, 6) with a variable limiting range that limits the spatial frequency range according to the specified spatial frequency range and the test image to a spatial frequency range corresponding to the details to be compared; a third image output means (for example 7) capable of changing a coherent two-dimensional emitted light complex amplitude distribution according to a spatial light intensity pattern of the light output of the Fourier transform pattern; and the third image output means An optical correlation processing device characterized in that it consists essentially of: a light detection means (for example, 8) that optically Fourier transforms a two-dimensional distribution pattern of the complex amplitude of output light and detects the light output; be.

Further, at least a first image output means (for example, a 3°
), and a first image output means for optically Fourier transforming the two-dimensional distribution pattern of the complex amplitude of the output light from the first image output means.
an optical Fourier transform means (e.g. 4');
Outputting a coherent image of a reference image group on an optical axis tilted with respect to the optical axis of the light beam emitted from the image output means of the image output means, A second image output means (e.g. 1
(°), a second optical Fourier transform means (for example, 2°) that optically transforms the two-dimensional distribution pattern of the complex amplitude of the output light from the second image output means; a superimposing means (for example, 5') for superimposing the Fourier transform pattern obtained by the optical Fourier transform means and the Fourier transform pattern obtained by the second optical Fourier transform means; and a Fourier transform superimposed by the superimposing means. a variable spatial filter (for example, 61) that limits the light receiving range of the pattern to a spatial frequency range corresponding to the size of the test image and a spatial frequency range corresponding to Jllall of the test image to be compared; third image output means capable of changing the coherent two-dimensional complex amplitude distribution of the emitted light according to the spatial light intensity pattern of the light output of the Fourier transform pattern superimposed by the superimposing means that has passed through the spatial filter; (For example, 7
°) and the two-dimensional distribution pattern of the output light complex amplitude from the third image output means are optically Fourier transformed, and the output thereof is input to the second image output means as its modulation signal. 3 optical Fourier transform means (e.g. 8'
), a light detection means (for example, 9゛) for detecting the light output from the third optical Fourier transform means, and an output related to the cross-correlation between the test image and the reference image completely detected by the light detection means. The optical correlation processing apparatus is characterized in that it essentially consists of a spatial filter control means for determining the saturation of the associative process from the spatial filter and changing the luminous flux restriction range of the spatial filter.

Further, it is preferable that the first image output means essentially consist of at least a coherent light source and one or more display bodies that display the image to be examined. The second image output means includes at least a coherent light source, a first spatial light modulator capable of modulating a spatial distribution pattern of a complex amplitude of a light beam from the light source, and a second image output means that includes at least a coherent light source; It is preferable that the display consists essentially of one or more display bodies that display a reference image group using the emitted light flux as input.

Further, the first spatial light modulator is divided into sections corresponding to each reference image constituting the reference image group, and each section is divided into:
It is preferable to receive a portion corresponding to each of the output lights from the third optical Fourier transform means, and whose transmittance or reflectance changes depending on the amount of the light. In addition, the third
The output from the optical Fourier transform means is received by a first two-dimensional photoelectric conversion element, and the first spatial light modulator converts electricity according to the output signal from the first two-dimensional photoelectric conversion element. It is preferable to use one that can be modulated.

The display body for displaying the reference image group is preferably a second space '# modulator that can be electrically modulated. Further, it is preferable that the display body for displaying the image to be examined is an incoherent coherent conversion element.

Further, the third image output means is configured to detect the incident light based on signals from at least the coherent light source and the second two-dimensional photoelectric conversion means that receives the output light of the Fourier transform pattern superimposed by the superimposition means. Preferably, the modulator essentially consists of a fourth spatial light modulator that modulates and outputs the complex amplitude distribution of the light beam. The third image output means has optical characteristics that are two-dimensional or three-dimensional depending on at least the intensity distribution of the coherent light source and the output of the input Fourier transform pattern superimposed by the superimposing means. A fifth spatial light modulator with a wood-like appearance is preferable.

[Operation] According to the configuration of the optical correlation processing device of the present invention as described above,
The test image presented by the first image output means and the second
The spatial pattern of the reference image group presented by the image output means is emitted onto optical axes tilted to each other, and is converted into a test image and the image by the first Fourier transform means and the second Fourier transform means. Each of the reference images is Fourier transformed.

Next, both Fourier transformed images are superimposed on the Fourier transformed plane to form multiple interference fringes of the reference image group and the test image. At this time, the spatial frequency range in which the reference image and the test image are to be compared is optimized using a spatial filter, the possible range of the multiple interference fringes is limited, and the light intensity of the multiple interference fringes is output from the third image output means. A coherent light beam having a light intensity distribution or phase distribution depending on the distribution is emitted.

This coherent light flux is optically Fourier-transformed by a third optical Fourier-transforming means, and the two-dimensional light intensity distribution obtained as a result represents the position of the test image and each reference image and the degree of correlation thereof. Become something.

The degree of correlation between , and - itself is detected by an optical detection means, and so on. However, when identifying and associative processing of test images, the present inventors, etc. It is more reliable to adopt the method described in . That is, the two-dimensional light intensity distribution according to the degree of correlation is input to the second image output means, and the output light intensity of the second image output means is a large part of the two-dimensional light intensity distribution. Make the part of the reference image that corresponds to larger and vice versa smaller.

By repeating these operations, the test image becomes
The light intensity emitted from the reference images having relatively low cross-correlation coefficients is sequentially reduced, leaving reference images similar in shape to the test image, and reducing the number of reference images to be compared. As a result of fewer reference images to be compared, the visibility of the interference fringes is increased by means of superimposing the Fourier transform patterns obtained by the first and second Fourier transform means, and the remaining images are , allowing accurate comparisons to be made. However, if the test image is an incomplete image with a part of the reference image missing, it will show a high cross-correlation coefficient when the light intensity emitted from the reference image is low to a certain extent. Even if the initial cross-correlation coefficient is not large, as the above trials are repeated, the light intensity emitted from the reference image gradually increases.

In this way, with repeated trials, the cross-correlation output with respect to the reference image corresponding to the test image gradually increases,
Furthermore, the cross-correlation coefficients for reference images that should not originally be associated gradually decrease, and eventually the images to be compared are narrowed down to one or a very small number.

After narrowing down the reference image candidates to be identified to one or a very small number through this association, the spatial frequency range limited by the spatial filter is set to the spatial frequency corresponding to the detailed structure of the image to be identified, and the target image and By determining detailed cross-correlation coefficients with the narrowed-down reference image, recognition and association processing of the test image can be performed quickly and accurately.

The prior correlation processing device of the present invention outputs at least a coherent image of a test image, and includes first image output means (for example, three ), and a first optical Fourier transform means (for example, four
) and electrically or optically output a coherent image of the reference image group on an optical axis tilted with respect to the optical axis of the light beam emitted from the first image output means. a second image output means (e.g. l) capable of temporal and spatial modulation; and a second image output means that optically Fourier transforms a two-dimensional distribution pattern of the complex amplitude of the output light from the second image output means. Optical Fourier transform means (e.g. 2)
a superimposing means (for example, 5) for superimposing the Fourier transform pattern obtained by the first optical Fourier transform means and the Fourier transform pattern obtained by the second optical Fourier transform means; a spatial filter with a variable limiting range that limits the light receiving range of the superimposed Fourier transform pattern to a spatial frequency range corresponding to the size of the test image and a spatial frequency range corresponding to details to be compared with the test image; (for example, 6), the coherent two-dimensional output light complex amplitude distribution can be changed according to the spatial light intensity pattern of the light output of the Fourier transform pattern superimposed by the superimposing means after passing through the spatial filter. a third image output means (for example 7);
and a light detection means (for example, 8) that optically Fourier transforms the two-dimensional distribution pattern of the complex amplitude of the output light from the third image output means and detects the light output. The test image is recognized by determining the cross-correlation coefficient between the test image and the reference image group.

Further, at least a first image output means (for example, a 3°
) k, a first image outputting means for optically Fourier transforming a two-dimensional distribution pattern of the complex amplitude of the output light from the first image output means;
optical Fourier transform means (e.g. 4°) k, said first
Outputting a coherent image of a reference image group on an optical axis tilted with respect to the optical axis of the light beam emitted from the image output means of the image output means, A second image output means (e.g. 1
'), a second optical Fourier transform means (for example, 2') for optically Fourier transforming the two-dimensional distribution pattern of the complex amplitude of the output light from the second image output means, and the first optical a superimposing means (for example, 5°) for superimposing the Fourier transform pattern obtained by the optical Fourier transform means and the Fourier transform pattern obtained by the second optical Fourier transform means; a variable spatial filter (for example, 6°) that limits the light reception range of the conversion pattern to a spatial frequency range that corresponds to the size of the test image and a spatial frequency range that corresponds to the details of the test image to be compared; , a third device capable of changing the coherent two-dimensional complex amplitude distribution of the output light in accordance with the spatial light intensity pattern of the light output of the Fourier transform pattern superimposed by the i11 recording means that has passed through the spatial filter. image output means (for example, 7') and optically Fourier transform the two-dimensional distribution pattern of the complex amplitude of the output light from the third image output means, and output the output to the second image output means. a third optical Fourier transform means (e.g. 8°) inputting as a modulation signal;
A light detection means (for example 91) for detecting the light output from the third optical Fourier transform means: an association from the output related to the cross-correlation between the test image and the reference image detected by the light detection means; spatial filter control means for determining saturation of the process and changing the luminous flux restriction range of the spatial filter;
For example, the method essentially consists of 92) and attempts to recognize a test image by finding a cross-correlation coefficient between the test image and a reference image.

At this time, the output light intensity from each reference image in the second image output means is changed in a positive feedback manner by the output of the third Fourier transform means according to the cross-correlation coefficient, so that the The influence of images with low correlation coefficients is selectively eliminated, and accurate identification can be performed at high speed from among a large number of reference images.

Further, the first image output means (for example, 3) essentially consists of at least a coherent light source (for example, a laser 11) and one or more display bodies (for example, an image display device 31) that display a test image. It is preferable that and,
The second image output means (e.g. 1) includes at least a coherent light source (e.g. laser 11) and a first image output means capable of modulating the spatial distribution pattern of the complex amplitude of the light beam from the light source.
It essentially consists of a spatial light modulator, and one or more display bodies (for example, image display device 16) that display a reference image group using the light beam emitted from the first spatial light modulator. Preferably.

Further, the first spatial light modulator (for example, the liquid crystal light valve 15) is divided into sections corresponding to each reference image constituting the reference image group, and each section is divided into sections corresponding to the third optical tool. Output light from the conversion means (e.g. screen 82
The transmittance or reflectance changes depending on the amount of light in the portion corresponding to each of the light intensity patterns (on the top). At this time, the third optical Fourier transform means (
For example, if the second spatial light modulator is an optical input type, the output from the Fourier transform lens 81) can be directly input to the second spatial light modulator, or if the second spatial light modulator is an electrical input type,
The light is completely received by the first two-dimensional photoelectric conversion element (for example, the two-dimensional photoelectric conversion element 91), and is transmitted as an electrical signal to the second spatial light modulator (for example, the liquid crystal light valve 15) through the image processing and liquid crystal drive circuit 92. ).

In addition, a display body (for example, 31°
) may be an incoherent-coherent conversion element, and the second image output means (for example, 1) may be an incoherent-coherent conversion element.
At least a coherent light source and a fourth spatial light modulator (e.g., image display device 16) capable of modulation by an electrical input that displays a set of reference images, which itself does not accept the function of liquid crystal light valve 15. It is preferable to have one.

The third image output means (e.g., 7) includes at least a coherent light source and a second image output means that receives output light from the Fourier transform pattern superimposition means (e.g., 5').
A fourth spatial light modulator (for example, 75). The third image output means (for example, 7) has optical characteristics that are two-dimensional or three-dimensional depending on the coherent light source and the intensity distribution of the incident output light from the superimposing means. and an inherently variable fifth spatial light modulator (eg 75').

Next, the optical correlation processing device of the present invention will be specifically explained using examples, but the present invention is not limited thereto.

[Embodiment 1] FIG. 1 is a schematic configuration diagram showing the functions of one example of an optical correlation processing device according to the present invention.

In the optical layout diagram of FIG. 1, the correlation processing device includes an image output means 1, an optical Fourier transform means 2, an image output means 3, an optical Fourier transform means 4, a Fourier transform pattern superimposition means 5, a spatial filter 6, It essentially consists of an image output means 7, an optical Fourier transform means 8, and a light detection means 9, and the structure thereof will be explained in detail below.

A beam 12 emitted from a coherent light source 11 such as a semiconductor laser or a gas laser is converted into a suitable beam system by a beam expander 13 and divided into two optical paths by a beam splitter 14.

The light beam 12 that has passed through the beam splitter 14 is further divided into two optical paths by the beam splitter 17. The light flux passing through the beam splitter 17 is displayed on the image display device [16
incident on . Here, the image display device [16] can be composed of a photographic film or a spatial light modulator capable of electrical input or optical input, and displays a reference image. (The above constitutes the second image output means 1.) The light beam 12g that has passed through the image display bag [16] passes through the Fourier transform lens 21 (this constitutes the second optical Fourier transform means 4) , enters the screen 71 placed on the Fourier transform surface.

On the other hand, the light beam 12b reflected by the beam splitter 17 is
The light beam 12a is reflected by the mirror 51 in a direction inclined with respect to the optical axis, and enters the image display bag [31]. Here, the image display device 31 displays the image of the subject Wi, and forms a spatial light modulator capable of receiving photographic film, electrical input, or optical input (forming the first image output means 3). )
The light beam 12b that has passed through the image display bag [31] passes through the Fourier transform lens 41 and enters the screen 71 placed on the Fourier transform surface.

Here, the Fourier transform pattern drawn on the screen 71 by the Fourier transform lenses 21 and 41 is
1 and Fourier transform lens 21.41 (this is the superimposing means 5
), the spatial frequencies of both Pulier transform patterns are made to match, so that the image display device f31
Multiple interference fringes are formed compared to the square of the two-dimensional Fourier transform of the complex amplitude distribution depicted in and 16. The light intensity distribution of this multiple interference fringe is determined by the spatial frequency filter 6 or the CCD.
By limiting the field of view of the two-dimensional photoelectric conversion element 72, the spatial frequency region of the images to be compared can be appropriately selected. This spatial filter 6 is configured by a spatial light modulator such as LCLV that can spatially change the transmittance distribution, and is controlled by an image processing device and a liquid crystal drive circuit 92.

Here, the image obtained by the two-dimensional photoelectric conversion element 72 passes through a video amplifier and a liquid crystal drive circuit 73 as an electric signal and is displayed on the LCLV 75. (7) LCLV
Similarly to LVLV16.31, 75 also constitutes a spatial light modulator (this constitutes the third image output means 7), and modulates the complex amplitude of the incident light and outputs it. The incident light beam 77 to the LCLV 75 is a light beam 12 emitted from the laser 11 divided into 11 by the beam snoring 14 C1, -
In 52, the light source is shared.

The light beam 77 emitted from the LCLV 75 passes through the °Fourier transform lens 81 and enters the screen 82 . At this time, the screen 82 is at the Fourier transform position with respect to the LCLV 75, and therefore the light intensity on the screen 72 depends on the degree of spatial cross-correlation or autocorrelation between the reference image group and the test image. is expressed.

Here, the mutual correlation positions of the reference images are in fact completely separated. This is because the light beams that illuminate the reference image group and the test image are oblique to each other, so that the interference fringes formed by both the reference image group and the test image on the screen 71 are different from the reference image. This is because the distance between the interference fringes is much narrower than the interval between the interference fringes formed by the interference fringes. Therefore, the screen 82 (which constitutes the light detection means 8) J:
From the 'ft, Wk distribution, a two-dimensional photoelectric conversion element 91 such as a COD can detect the position of a reference image that has a strong correlation with the test image and the degree of correlation.

[Example 2] The present invention can also be applied to the method described in the specification of the above-mentioned application by the above-mentioned inventors.

As explained in the specification of the previous application, when the test image is a pattern with a part of the reference image missing or there are a large number of reference images, the interaction between the test image and the reference image may occur. The degree of correlation is reduced due to the lower visibility of the interference fringes. For this purpose, by using a feedback system that adjusts the amount of light irradiating the corresponding reference image based on the detected cross-correlation value, the detection sensitivity can be increased by narrowing down the reference image candidates corresponding to the test image. , which improves the accuracy of recognition and association.

FIG. 3 shows an optical system layout when the above method is applied to the present invention. In the optical layout shown in FIG. °, image output means 3 ° optical Fourier transform means 4 °,
It essentially consists of a Fourier transform pattern superimposing means 5', a spatial filter 6', an image output means 7', an optical Fourier transform means 8', and a light detection means 9'.

Hereinafter, its configuration will be explained in detail with respect to the points that are different from the configuration shown in FIG. 1 of the first embodiment described above.

The means for detecting the degree of correlation on the screen 82 in FIG. 3 are the same as those described in Embodiment 1 in FIG. It is assumed that one of the above is partially missing. In this case, by limiting the field of view of the spatial filter 6° or the two-dimensional photoelectric conversion element 72, information on detailed parts unnecessary for knowing the general shape of the image is cut out.

This spatial filter 6° is controlled by the image processing device and the liquid crystal drive circuit 92, and initially has a high transmittance at a certain distance from the optical axis so that only the spatial frequency corresponding to the size of the image is transmitted. The transmittance on the outside is low.

Now, the light intensity on the screen 82 is read by the two-dimensional light M and the conversion element 91, and sent as an electrical signal to the image processing device and the liquid crystal drive circuit 92, and the amount of reciprocal correlation with each reference image is normalized. By determining the transmittance distribution of the LCLV 15 accordingly, the amount of light applied to each reference image can be changed.

That is, for example, the light flux that irradiates the reference image that has the highest degree of correlation with the test image maximizes the transmittance of the pixel portion of the LCLV 15 through which it passes, and the other reference images have the highest degree of correlation. The transmittance is determined according to the degree of correlation normalized by .

In this way, the above operations can be repeated by manually creating a pattern after changing the transmittance of the LCLV 15 and changing the amount of light that can be irradiated onto each reference image.

By the way, when the test image is a partially missing pattern of the reference image, the visibility of the interference fringes increases when the amount of light decreases with respect to the reference image to be associated. On the other hand, for a reference image that should not be associated, a decrease in light intensity only reduces the visibility of the interference fringes. ), but after trying the above operation several times, the reference image to association 1 is recalled.

In addition, if there are several reference images with a high degree of correlation with the test image, a threshold level is set for the degree of correlation for some reference images with extremely low degrees of correlation, and the spatial The transmittance of the spatial light modulator may be set to the lowest value. In this case, after several trials, the reference image whose correlation degree is lower than the threshold value is also set to the lowest transmittance value of the spatial light modulator. If you do this, you can get results quickly.

Furthermore, since the number of reference images is limited at the initial stage, there are fewer objects to compare in subsequent operations, the visibility of interference fringes increases, and correct recognition is achieved.

In addition, if there is a reference image that should not be associated but has a high cross-correlation value with respect to the test image, the cross-correlation peak due to the reference image that should be associated is initially relatively small, and the trial C goes through a process of repeatedly increasing, but at the point when this correlation peak light amount exceeds the correlation peak light amount from the reference image that initially had the highest correlation peak, or the peak light amount of both changes. When the correlation peak light amount becomes smaller, the amount of light irradiated to the reference image whose correlation peak light amount was initially smaller is set as the maximum amount of light irradiated, and the amount of light irradiated to the other reference images is made smaller than that, so that the association converges more quickly.

Furthermore, by comparing the degree of correlation at the time when the cross-correlation does not change as a whole when the number of trials increases, it is also possible to vaguely judge the degree of correlation between the test image and the reference image.

In this example, if a rule is set so that the transmittance to be changed is high for a reference image with a high degree of correlation and low for other reference images, then what can be done? Needless to say, it is fine.

Then, as described above, the change in the correlation peak output is converged, and the image processing device determines the only candidate or a small number of candidates with large correlation outputs from among the reference image group.Then, the image processing device and the control of the liquid crystal drive circuit 92, the spatial frequency range limited by the spatial filter 6' is
Expand the spatial frequency range to correspond to the details you want to identify in the image.

For example, if an LCLVI 5 and an image display device are provided, an interference fringe pattern based on the Fourier transform patterns of these Fourier transform patterns is irradiated onto the screen 71, and that pattern is written on the LCLV 75, and on the screen 82, Depending on the interference fringes, a correlation peak output is obtained at a position corresponding to the relative distance between the two images being compared.

This correlation peak output indicates the degree of correlation between the two images, and roughly indicates which part of the test image is missing due to the difference between the peak output and the position that should appear when the two images perfectly match. You can find out if there are any.

At this time, since the number of reference images is limited to a very small number, the visibility of the interference fringe pattern between the test image and the reference image on the screen 71 is improved, and the two-dimensional photoelectric conversion element 72
Even if the resolution and dynamic range of the LCLVI5 are not large, the screen 72 can detect the degree of correlation for the associative process with high accuracy, the position and degree of omission in the test image, and perform recognition processing on the test image. can be ensured.

[Embodiment 3] In this embodiment, FIG. 2 shows an optical layout diagram of another example of the optical correlation processing device of the present invention.

In this embodiment, a beam 12 emitted from a laser 11 passes through a beam expander 13 and enters a beam splitter 14 . The light beam completely reflected by the beam splitter 14 is further turned into a reflected light beam 12b and a transmitted light beam 12a by the beam splitter 17.

Next, the transmitted light beam 12a enters the image display bag [16] on which the reference image group is drawn. This image display bag [16 (this constitutes the second image output means 1) is one in which a plurality of reference image groups are recorded on a photographic film, or a plurality of reference image groups are inputted electrically or optically. It constitutes a possible spatial light modulator.

Now, the light beam 12a that has passed through the image display device 16 passes through the Fourier transform lens 21 (which constitutes the second optical Fourier transform means 4) and enters the LCLV 75° placed on the second optical transform surface. On the other hand, the reflected light flux 12b is
The light beam 12a is reflected by the mirror 51 in a direction inclined with respect to the optical axis, and enters the image display device 31 (which constitutes the first image output means 3) on which the test image is drawn.

This image display device 31 is similar to the image display device 16 described above.

Now, the light beam 12b that has passed through the image display bag [31] passes through the Fourier transform lens 41 (which constitutes the first optical Fourier transform means 2) and enters the LCLV 75' placed on the Fourier transform surface.

Here, by the Fourier transform lenses 21 and 41, the LC
The Fourier transform pattern drawn on L775' is made to match the spatial frequencies of both Fourier transform patterns by the mirror 51 and the Fourier transform lens 21.41 (which constitutes the superimposing means 5), so that the image is not displayed. Multiple interference fringes are formed that are proportional to the square of the two-dimensional Fourier transform of the complex amplitude distribution drawn by the devices 31 and 16.

Here, LCLV75° is a reflective liquid crystal light valve as shown in FIG. This liquid crystal light valve is A
R foot layer 109, glass substrates 101 and 106, transparent electrode 102.10B, spacer 103, dielectric mirror 10
5. It is composed of a liquid crystal layer 104 and a photoconductive layer 107, and the photoconductive layer 107 and a dielectric mirror 105 are arranged between the liquid crystal panel 104 sandwiched between transparent electrodes 102 and 108.

Here, the dielectric mirror 105 is arranged closer to the liquid crystal layer 104 (on the right side in the figure) than the photoconductive layer 107, and this is the direction in which the readout light is incident.

At this time, when a voltage is applied between the transparent electrodes on both sides (i.e., 102 and 108) and the writing light A is irradiated,
Depending on the amount of writing light A, the resistance value in the photoconductive layer 107 decreases, resulting in a drop in the resistance value on each part of the liquid crystal.
For resistance division, 1' change per person Δ, readout potential B is:
Its plane of polarization rotates 4, therefore, the beam splitter 14
The light beam 77 that has passed through the LCLV 7 passes through the mirror 74, the polarizing beam splitter 76, and the mirrors 79 and 78.
When irradiated from the readout side of 5°, the plane of polarization is rotated according to the light intensity distribution of the multiple interference fringes, and the reflected light is
The light passes through mirrors 78 and 79 and enters the polarizing beam splitter 76.

Here, only the amount of light that has undergone rotation of the plane of polarization is reflected and enters the Fourier transform lens 81.
The Fourier transform intensity distribution pattern of the pattern completely reflected by ' is completely irradiated onto the screen 82F.

As described above, this dependency distribution pattern represents the degree of spatial cross-correlation and autocorrelation between the reference image group and the test image.

In step 1, the cross-correlation position between the reference images and the cross-correlation position between the test image and the reference image group are in fact completely separated. This is because the light beams that irradiate the reference image group and the test image are oblique to each other, so the LCLV75
This is because the interference fringes formed by both the above reference image group and the test image are much narrower than the interval between the interference fringes formed by the reference images.

Therefore, it is possible to receive and process the light intensity distribution on the screen 82 using a two-dimensional photoelectric conversion element 91 such as a COD and an image processing device 92, and to detect the position and degree of correlation of a reference image that has a strong correlation with the test image. can. Note that the control of the spatial filter 6 by the image processing device is the same as in Example 1.2.

The liquid crystal panel and optical shutter array used here are
They can be collectively referred to as electrically addressed spatial light modulators. ``As an optically addressed spatial light modulator,
In addition to those listed here, there are also possible matrix electrodes in which a matrix electrode is formed in a medium with an electro-optic effect, such as PLZT, BSO, lithium niobate, KTP, etc., and these include those listed in this example, It can be used as well.

[Real M Example 4] Next, FIG. 4 shows a configuration diagram of another embodiment of the optical correlation processing device of the present invention.

This example is another example adapted from the method disclosed in the specification of the patent application previously filed by the present inventors.

In the optical layout diagram of FIG. 4, the correlation processing device includes image output means 1', optical Fourier transform means 2', image output means 3°, optical Fourier transform means 4°, and Fourier transform pattern superimposition means 5'. , spatial filter 6°, image output means 7', optical Founoe transformation means 8', light detection means 9'
It consists of Hereinafter, the configuration will be explained in detail with respect to points different from the second embodiment (FIG. 3) described above.

The difference from the configuration shown in FIG. 3 above is that the image output means 1° performs feedback according to the degree of correlation between the test image and the reference image group.

Now, in the first image output means 1', the polarization plane of the laser 11 is tilted at an angle of 45 degrees with respect to the plane of the paper and the direction perpendicular to the plane of the paper, and a beam 12 is emitted from the beam expander 13. After a reflected beam and a transmitted beam are obtained by the beam splitter 14', the polarizing beam splitter 17 reflects the S-polarized component of the reflected beam and transmits the p-polarized component.

Subsequently, the light beam 12a consisting of the p-polarized component is LCLVI
5': Incident, LCLV 15' is a reflective liquid crystal light pulp having a structure as shown in FIG. That is, an AR coat layer 119, a glass substrate 11g, a transparent electrode 117, a photoconductive layer 116, an At vapor deposition layer 115, a liquid crystal layer 114, and a spacer 113 are laminated.

Come on, this reflective LCD light bulb! 5', an Al vapor deposition layer 115 is disposed between a transparent electrode 117 and a liquid crystal panel sandwiched between 117', and the Al vapor deposition layer is divided into 115a of required pixel size. This LCLV
In I5', the size of this pixel is the size of the reference image in the image display [16].

Here, the vapor-deposited layer 115 of AN is arranged closer to the liquid crystal layer (on the right side in the figure) than the photoconductive layer 116, and these are the incident direction of the readout light. At this time, a voltage is applied between the transparent electrodes on both sides (i.e., 117 and 117:),
When the writing light A is irradiated, the resistance value of the photoconductive layer 116 decreases in each divided pixel 115a depending on the amount of the writing light A, and the transparent electrode and the divided AP vapor deposition layer become approximately at the same potential. , the voltage applied to the liquid crystal corresponding to each divided pixel changes, and the polarization plane of the incident readout light B rotates. Therefore, the luminous flux 12 consisting of the p-polarized component
a undergoes rotation of the plane of polarization according to the writing light A that has entered the LCLVI 5', and the reflected light is rotated by the polarizing beam splitter 17 according to the intensity distribution of the writing light A.
', and the image display device 1 receives the S-polarized light as S-polarized light.
6.

Hereinafter, a composite Fourier transform pattern of the test image and the reference image group is drawn on the LCLV 75' using the S-polarized light beam,
The process of reading out the light beam 77 that has passed through the beam stabilizer 77 is the same as that described in FIG. 2 above, so 4 is omitted.

The light beam whose polarization plane has been rotated by the 75° LCLV is reflected by the polarizing beam splinter 76, and the correlation pattern between the test image and the reference image group is observed on the screen 82 by the Fourier transform lens 81. . on the other hand,
This light beam is split by a beam splitter 83 and made incident on a reflective liquid crystal light valve 15'. However, LCL
The light flux incident at V15° has its optical axis, that is, the 0th order light spot position, shifted by the beam splitter 83 or the like to the LCL.
In advance, so that the light spot of the corresponding cross-correlation peak comes to the position 84 of each reference image on VI 5',
Set the position of the reference image and the arrangement of the optical system.

Therefore, from now on, the reference image with a strong degree of correlation is irradiated with a light beam having a higher intensity with respect to the test image, and the reference image with a low degree of correlation can be irradiated with a light beam having a lower intensity. Note that this cross-correlation intensity output is obtained by detecting the light intensity distribution of the screen 82 with a two-dimensional photoelectric conversion element 91 such as a CCD, and from this information, an image processing and liquid crystal driving circuit 92 converts the spatial filter 6'. is controlled.

In the optical information processing device of the present invention, although there are differences in specifications regarding the part that functions as a spatial light modulator, in principle they are all similar in terms of electrical address type and optical address type. are available.

Examples of electrically addressable types include the above-mentioned liquid crystal light half frame, PLZT, KDP, and B50 (B i ++S).
Ceramics and crystals that exhibit electro-optic effects such as 1Oss), which have a matrix electrode added to them, are often used.

In the example of the optically addressed type, the same material as the electrically addressed type is used.
A combination of photoconductive layers such as those explained in FIGS. 5 and 6 is a boat fishing.

However, in a crystal having a photovoltaic effect such as BSO or BaTiOs, a photo-induced refractive index change occurs due to spontaneous polarization depending on the intensity of incident light, so there is no need to add a photoconductive layer. Note that these spatial light modulators can be configured as either a transmissive type or a reflective type. However, in cases where the read light completely erases the information of the write light in an optical addressing type, the wavelength ranges of the read light and write light are separated so that the read light does not affect the write information. It is necessary to take measures such as making this possible.

Further, when using an electrically addressed type, a two-dimensional photoelectric conversion element and its driving circuit are required to obtain the input image, but there is an advantage that the signal can be easily processed.

[Embodiment 5] A normally used incoherent-coherent conversion element belongs to the optically addressed reflective spatial light modulator as described above, and when this is used as the image display device 16, An imaging optical system is required to make the input image (test image) incident on the incoherent-coherent conversion element. A configuration diagram of an example of such an optical system is shown in FIG.

In the correlation processing apparatus shown in FIG. 7, a beam 12 from a laser 11 is reflected by a beam t, a beam 14t', and enters an image display device 31°. Here, the image display device [31
° is the incoherent image corresponding to the image display area under test.
Consists of coherent conversion elements. Here, the incoherent-coherent conversion element receives optical modulation input from the reflection side of the light beam 12.

For example, as shown in the figure, this modulation input causes the image 18 of the test image S to be incoherent and
This is an image formed on the screen of a coherent conversion element. In addition, the reference image group and the four-dimensional light! Feedback information based on the degree of cross-correlation detected by the conversion element 91, that is, information on the light intensity to be emitted from the image display device 16'' for each reference image, is depicted as being superimposed.

That is, in the correlation processing device of FIG. 7, the image display device 16°
The receiver has the functions of the LCLV 15 and the image display device 16 of the correlation processing device shown in FIG. 3 at the same time. Here, we will explain the foot function according to the degree of correlation! Although the configuration of the feedback system has been described as an example, as mentioned above, it goes without saying that even if the feedback system is omitted, the same effect can be achieved in terms of increasing the number of reference image groups.

Now, regarding other parts, there are differences in the combinations of the spatial light modulators used, such as whether they are electrical addressing type or optical addressing type, and whether they are transmissive type or reflective type. Since the explanations from FIG. 1 to FIG. 4 are almost the same, they will be omitted.

Note that when a spatial light modulator is used in the reference image display section, the reference image can be drawn directly, making it easier to rewrite the image.
Initially, a large number of reference images and images with rough resolution or contours of the test image are presented at once, associations are made, and the number of reference image candidates is gradually reduced, and the images are displayed in a larger size to increase their resolution. Finally, by narrowing down the reference image candidates to one and detecting the degree of correlation with high precision, the test image can be recognized reliably.

In addition, the spatial filter 6 in the above-mentioned embodiment can basically be considered as a spatial light modulator as follows.
Of course, in this case, it is convenient to use a transparent electrical addressing type in terms of configuration and control. Further, a configuration similar to a mechanical diaphragm can also be adopted.

As can be seen from the above description, any combination of these spatial light modulators is possible, and therefore, the correlation processing device of the present invention can take many embodiments depending on the combination. It will be possible.

[Effects of the Invention] The optical correlation processing device according to the present invention achieved the above-mentioned effects.To summarize them, the following remarkable technical effects were obtained.

That is, first, the phase difference calculation between the reference image and the test image is performed in real time without using any means such as holography, and the reference image group and the test image are placed on optical axes tilted relative to each other. By subsequently obtaining a composite Fourier transform pattern, it was possible to provide a correlation processing device that can significantly increase the number of reference images, such as 5-.

Second, by configuring the feedback system based on the degree of correlation between the test image and the reference image group, it was possible to provide a correlation processing device that can dramatically increase the number of reference images.

Third, using the same reference image memory and test image,
Since correlation detection can be performed by changing the spatial frequency, it has been possible to provide a correlation processing device that can accurately associate and identify test images.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the configuration of an example of the optical correlation processing device of the present invention. FIG. 2 is a schematic configuration diagram showing the configuration of another example of the optical correlation processing device of the present invention. FIG. 3 is a schematic configuration diagram showing the configuration of another example of the optical correlation processing device of the present invention. FIG. 4 is a schematic configuration diagram showing the configuration of still another example of the correlation processing device of the present invention. FIG. 5 is a schematic configuration diagram showing the configuration of a reflective liquid crystal light pulp used in the present invention. FIG. 6 is a schematic diagram showing the structure of another reflective liquid crystal light pulp used in the present invention. FIG. 7 is a schematic configuration diagram showing the configuration of still another example of the optical correlation processing device of the present invention. [Explanation of symbols of main parts] 1.3.7 Image output means 2. 4.
8...Optical Fourier transform means 5...
, , , Fourier transform pattern superimposition means 6 , ,
, Spatial filter 9 , Light detection means 11 , Laser 12.12a, 12b, 77 , Luminous flux 1
3. ... ・Beet Extract/Kunda 15.15
', 75.75° 991.1. . Liquid crystal light pulp 16.31 , , , , , Image display device 18 , ,
, , , , Test object 21.41.81 , , , , , , '7-Lie transform lens 51.74.78.79. , , , , , Mirror 7
1.82 , , , , , Screen 72.91
, , , , , , Two-dimensional photoelectric conversion element 73 , , , ,
, , video amplifier and liquid crystal drive circuit 17' 76,
, , , , , polarizing beam splitter 92 , , , , ,
, , Image processing and liquid crystal drive circuit 101.106.11
B, , , , , Glass substrate 102.108.11
7.117' ,,,,,,. Transparent electrode 03.113. , , , , Spacer 04.114. , , , , , Liquid crystal layer 05 , , , , , Dielectric mirror 07.116. , , , , , Photoconductive layer 09 , , ,
, , , A R coat layer 15 , , , , , , A l
Vapor deposited layer

Claims (1)

[Scope of Claims] 1. At least a first image output means that outputs a coherent image of a test image and is capable of temporally and spatially modulating the complex amplitude of output light electrically or optically; a first optical Fourier transform means for optically Fourier transforming a two-dimensional distribution pattern of the complex amplitude of the output light from the first image output means; and an optical axis of the light beam emitted from the first image output means. a second image output means capable of temporally and spatially modulating the complex amplitude of the output light electrically or optically and outputting a coherent image of the reference image group on an optical axis tilted with respect to the second image output means; a second optical Fourier transform means for optically Fourier transforming a two-dimensional distribution pattern of the complex amplitude of output light from the second image output means; and a Fourier transform pattern obtained by the first optical Fourier transform means. and a superimposing means for superimposing the Fourier transform patterns obtained by the second optical Fourier transform means, and a light receiving range of the Fourier transform patterns superimposed by the superimposing means in a space corresponding to the size of the test image. a spatial filter with a variable limit range that limits the frequency range and the test image to a spatial frequency range depending on details to be compared; a third image output means capable of changing a coherent two-dimensional complex amplitude distribution of output light according to a spatial light intensity pattern; and a two-dimensional distribution of complex amplitude of output light from the third image output means. What is claimed is: 1. An optical correlation processing device comprising: a light detection means for optically Fourier transforming a pattern and detecting its light output. 2. At least a first image output means that outputs a coherent image of a test image and is capable of temporally and spatially modulating the complex amplitude of output light electrically or optically; and the first image output means. a first optical Fourier transform means for optically Fourier transforming a two-dimensional distribution pattern of the complex amplitude of output light from the first image output means; a second image output means that outputs a coherent image of a reference image group on the optical axis and is capable of temporally and spatially modulating the output light complex amplitude electrically and spatially; and the second image output a second optical Fourier transform means for optically Fourier transforming a two-dimensional distribution pattern of the complex amplitude of output light from the means; a Fourier transform pattern obtained by the first optical Fourier transform means; 2
a superimposing means for superimposing the Fourier transform patterns obtained by the optical Fourier transform means of the superimposing means; a limiting variable spatial filter that limits the spatial frequency range according to the details to be compared of the images to be compared, and a spatial light intensity pattern of the light output of the Fourier transform pattern superimposed by the superimposing means that has passed through the spatial filter; a third image output means capable of changing a coherent two-dimensional output light complex amplitude distribution; and an optical Fourier transformer to optically convert the two-dimensional distribution pattern of the output light complex amplitude from the third image output means. a third optical Fourier transform means for converting and inputting the output thereof to the second image output means as a modulation signal; and a light detection means for detecting a light output from the third optical Fourier transform means. and a spatial filter control means for determining the saturation of an associative process based on the output related to the cross-correlation between the test image and the reference image detected by the light detection means, and changing the luminous flux restriction range of the spatial filter. An optical correlation processing device characterized by 3. The optical correlation according to claim 1 or 2, wherein the first image output means essentially consists of at least a coherent light source and one or more display bodies that display the image to be examined. Processing equipment. 4. The second image output means includes at least a coherent light source, a first spatial light modulator capable of modulating a spatial distribution pattern of the complex amplitude of a light beam from the light source, and the first
4. The optical correlation processing device according to claim 2, wherein the optical correlation processing device essentially consists of one or more display bodies that display a group of reference images whose input is the light flux emitted from the spatial light modulator. 5. The first spatial light modulator is divided into sections corresponding to each reference image constituting the reference image group, and each section corresponds to each of the output lights from the third optical Fourier transform means. 5. The optical correlation processing device according to claim 4, wherein the optical correlation processing device receives a portion of light corresponding to the amount of light and changes transmittance or reflectance depending on the amount of light. 6. The output from the third optical Fourier transform means is:
The light is received by a first two-dimensional photoelectric conversion element, and the first
6. The optical correlation processing device according to claim 4, wherein the spatial light modulator is electrically modulated according to the output signal from the first two-dimensional photoelectric conversion element. 7. The optical correlation processing device according to claim 1, wherein the display body that displays the reference image group is a second spatial light modulator capable of electrical modulation. 8. The optical correlation processing device according to any one of claims 1 to 7, wherein the display body for displaying the test image is an incoherent-coherent conversion element. 9. The third image output means detects the incident light based on at least the signals from the coherent light source and the second two-dimensional photoelectric conversion means that receives the output light of the Fourier transform pattern superimposed by the superimposition means. 9. The optical correlation processing device according to claim 1, comprising a fourth spatial light modulator that modulates and outputs the complex amplitude distribution of the light beam. 10. The third image output means depends at least on the intensity distribution of the coherent light source and the output of the input Fourier transform pattern superimposed by the superimposition means,
9. The optical correlation processing device according to claim 1, wherein the optical correlation processing device is essentially a fifth spatial light modulator whose optical characteristics change two-dimensionally or three-dimensionally.