JPH0756187A - Device for extracting contour of image - Google Patents

Abstract

PURPOSE:To provide an image contour extracting device for extracting the contour of an image under a condition irradiated. with natural light even in the case an inputted image includes the linear elements of all the spatial frequencies, furthermore, a body moving at extremely high speed is the object to be processed. CONSTITUTION:The device is constituted of a polarization modulating means 210 for receiving read-out light and write-in light so as to change the polarization angle of the read-out light in accordance with the light intensity of the write-in light, a means 200 for supplying the light of the inputted image to the polarization modulating means 210 as the write-in light, an image reading means 220 for supplying the light polarized in one direction to the polarization modulating means 210 as the read-out light, a polarized image outputting means 230 for transmitting the light polarized at a prescribed angle out of the light outputted from the polarization modulating means 210 and outputting the light. A relative angle between a polarization direction of the polarization modulating means 210 in terms of properties and the polarization angle of the read-out light is set at a prescribed angle. Furthermore, the image inputting means 200 is provided with a means for adjusting the light intensity of the inputted image, the focal depth of the image and the focus of the image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour extracting method and a contour extracting apparatus using parallel light calculation.
More specifically, the two-dimensional parallel optical operation is performed on the input image as light at high speed, and is particularly useful in the field of optical image processing such as image recognition applications.

[0002]

2. Description of the Related Art Conventionally, an electric method, an optical method, a method using a special element, and a method using a spatial light modulator are known as methods for extracting the contour of an image.

An electrical method will be described as the first conventional technique. For example, in an electrical method in which an image pickup means such as a CCD camera is used to input a symmetrical image for contour extraction processing and an optical signal from the input image is once converted into an electrical signal, an image at a certain time is stored in an image memory, A mask process such as Roberts or Laplacian is executed to perform a contour extraction process. This method requires a frame rate required to store an electrical signal in the frame memory, for example, a calculation time of 1/30 seconds or more per screen, and the calculation speed of the contour extraction processing is affected by the frame rate of the input device. box office.

Further, the processing time of the mask processing for contour extraction increases as the size of the mask used, that is, the number of pixels increases.

On the other hand, a high-speed input system has been proposed in which the frame rate of the input device is faster than that of the above-mentioned image pickup means, that is, a moving image of an object moving at high speed is continuously input using a high-speed camera or the like. . According to this, normally, the input image is once recorded in a storage medium such as an image memory or a recording tape, and after the recording is completed, the contour extraction processing is performed for each recorded frame.

Further, in the case of the electrical processing method, since the two-dimensional spatial position information of the image corresponds to the memory address of the image memory, the position information is converted when the spatial position information is converted into the memory address. A quantization error with respect to occurs. Further, for example, the magnitude of the quantization error of the line segment changes depending on the direction in the image. Therefore, in the contour extraction mask processing, the accuracy with which the contour component is extracted varies depending on the direction of the contour to be extracted.

An optical method will be described as the second conventional technique. It is known that high speed of light can be utilized in an optical method of extracting the contour of an image by optical Fourier transform of an image using a lens and high-pass filtering processing of a frequency plane.

On the other hand, the spatial filtering method in the frequency plane shows desirable performance when processing a feature (for example, a line drawing) having a substantially constant spatial frequency contained in the input image. However, in a more general contour extraction process, since various spatial frequencies included in an image are mixed from low to high, one type of fixed filter in the frequency plane is used to outline an image having a wide range of spatial frequencies. When applied to extraction, only non-uniform and unsharp contours are obtained for the whole image. In the optical method, in particular, the shape and size of the filter are known to determine the performance of the filtering process. The optical method is described in, for example, "Applied Optics I", by Tatsuro Suzuki, published by Asakura Shoten.

The input image on which the optical Fourier transform and filtering process can be performed is an image carried with a single wavelength of light (typically exhibiting coherent light). Therefore, in order to perform the optical filtering process, coherent light representing the characteristics of the object is formed by some irradiation means and used as an input image. For example, when processing an image under natural light irradiation conditions, the image is usually photographed on a photographic film, and single-wavelength light such as laser light is irradiated from the back surface to form an input image, or The wavelengths are once aligned via the incoherent-coherent conversion element and then used as the input image.

As a third conventional technique, a special optical element will be described. For example, the feature extraction of the input image using a special optical element is performed in “Optical Neurochips for Direct Im
ageProcessing (optical neurochip for direct image processing) ", 1992 IEICE Spring Conference Proceedings, D-83, reported by Kuma et al. Since the number of pixels of the element is small, the accuracy of feature extraction is limited. Further, the application range is limited by the control method of the element, the amount of energy to be applied, and the response time of the element.

In contrast to the above-mentioned prior art, Suzuki et al. Have proposed a method that can be applied to an image of an object moving at high speed, or an image in which the size of the object is large and the extraction result is highly required. Image Edge Extraction Using FLC-SLM ", Proceedings of 53rd Annual Meeting of the Applied Physics Society of Japan, 1992. Here, a spatial light modulator that modulates the polarization state of the liquid crystal according to the intensity of the input light is used as a polarizer, and the relative angle between the polarization planes of the polarizer and the analyzer is matched with the rubbing angle at the time of making the polarizer. An example in which an edge of a binary image is extracted has been reported. In this method, in order to output the edge of the input image at the rubbing angle, the light intensity of the input image, the erasing time of the image already stored, and the writing time of a new image are set for each device. Finely adjust to.

[0012]

There are the following problems in the above-described image contour extraction by the conventional technique.

In the electrical feature extraction method, the feature extraction processing speed is slow because an input circuit and an electric circuit whose response speed is slower than the speed of the optical signal are interposed.

For example, as described above, since the calculation time depends on the frame rate of the input device, it cannot be grasped within the frame rate, that is, the contour of an object moving at a very high speed compared with the frame rate is calculated in real time. Cannot be extracted with. On the other hand, in the case of input from a high-speed camera or the like, since the image is temporarily stored, the real-time property of the feature extraction processing cannot be expected at all.

Extraction for contour components other than these is compared with the precision of contour component extraction in a spatial specific direction, for example, vertical direction or horizontal direction, which can reduce the quantization error when converting a spatial position into an image memory address. The accuracy is poor, and if the mask size is expanded in order to improve the accuracy of contour component extraction, the processing time becomes long.

Further, when processing an image including a fine structure, it is necessary to increase the number of pixels of the input image, which increases the processing time.

The optical method cannot deal with all spatial frequencies contained in the input image with one kind of fixed filter. For example, there are differences in the spatial frequency components included in the contour component of the processing target image when the size of the contour component of the object in the input image is large and when there are many contour components of small size. Therefore, even if the purpose of spatial filtering is the same, it is necessary to grasp the tendency of the spatial frequency component of the target image and select an appropriate spatial filter.

Further, the application range of the optical method is limited to the image carried by the light of a single wavelength as the input image. Therefore, for example, a natural light image cannot be handled as it is as an input image, and thus an illumination means for irradiating the target image with coherent light is required. Therefore, when a moving image or a three-dimensional object is to be processed, not only image input but also a reliable irradiation method of the object is a problem.

In the method using a special optical element, the number of pixels is limited, the element control method is complicated, the energy to be applied is large, and moreover, real-time image input such as moving image processing and feature extraction processing are required. There is a problem that the response speed of the device is slow for the required application.

Further, in the conventional method using the element for modulating the polarization state of the liquid crystal, the polarization angle is adjusted to the rubbing angle at the time of producing the spatial light modulator as described above. At this time,
In order to extract a high-contrast edge portion of the input image, the light intensity of the input image, the voltage applied to the spatial light modulator for erasing, writing, and reading the image, and the application time can be finely adjusted. It is necessary and has practical problems.

The above conventional method is generally regarded as a problem in the field of image processing such as an object moving at high speed, a three-dimensional object illuminated by natural light, a two-dimensional contour, and an image having a wide distribution range of spatial frequency components. It is difficult to apply it to the image to be processed.

The present invention has been made in view of the above problems of the prior art.
Even if the input image includes line elements of all spatial frequencies, and even if an object moving at a very high speed is to be processed, an image contour extraction device that performs image contour extraction under natural light irradiation conditions, The purpose is to provide a simple structure, low energy consumption, easy controllability, and low cost.

[0023]

FIG. 1 is a block diagram showing the principle of the present invention.

The image contour extraction device of the present invention receives the read light and the write light, and changes the polarization angle of the read light according to the light intensity of the write light, and the light of the input image is polarized. Means for supplying the light as writing light to the means, image reading means for supplying light polarized in one direction as the reading light to the polarization modulating means, and output light of the polarization modulating means polarized at a predetermined angle. And a polarized image output means for transmitting light and outputting the polarized light. The relative angle between the polarization direction of the characteristic of the polarization modulation means and the polarization angle of the readout light is set to a predetermined angle.

Further, the image contour extracting device of the present invention is
The image input means has means for adjusting the light intensity of the input image, the depth of focus of the image, and the focus of the image.

[0026]

In the contour extracting apparatus of the present invention, the input image is adjusted by the image inputting means into an image having an appropriate light intensity and written in the polarization modulating means in real time. On the other hand, when the reading side of the polarization modulator is irradiated with the linearly polarized readout light, it is read out from the polarization modulator as an optical signal whose polarization state is modulated according to the light intensity distribution of the input image. Of this optical signal, the polarization information corresponding to the contour information of the image is extracted with a constant width by the reading means, and is output on the output surface by the polarization image output means.

Here, the outline of the image is a boundary between a bright portion and a dark portion in the image, that is, a portion where the brightness is changed in the image. Explaining in more detail the part where the brightness changes, for example, comparing the brightness of adjacent small areas in the image (for example, one pixel of the image), the brightness changes unevenly, but to a certain extent. For example, when the average brightness is compared for each area, the brightness gradually changes. In the contour extraction according to the present invention, a halftone portion in which the brightness gradually changes between the bright portion and the dark portion as described above is detected and the contour is extracted. For example, when the image is blurred (smoothed) by slightly defocusing, the width of the halftone portion becomes wider. On the contrary, when the focus is adjusted and the depth of focus is decreased, the image is emphasized and the width of the halftone portion is narrowed.

The contour is extracted by the contour extracting device of the present invention as follows. In the polarization modulator that rotates the polarization direction of the readout light according to the presence or absence of light in the input image or the intensity thereof and outputs the brightness information of the input image as the difference in the polarization state, the polarization direction corresponding to the presence or absence of light or the intensity By setting the bisector direction of the angle to be made to coincide with the polarization direction of the reading light or by setting the angle so as to form an angle of 45 degrees with respect to the polarization direction of the reading light, the boundary between the dark and light of the input image. Is extracted as a contour.

Further, the contour extracting device of the present invention forms an image on the two-dimensional polarization modulation element while adjusting the light intensity of the input image, and the two-dimensional polarization modulation element of the two-dimensional polarization modulation element is formed according to the light intensity distribution of the input image in real time. A series of operations are optically executed, such as modulating the polarization direction of the reading light and forming and outputting the contour of the image.

[0030]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 shows a system configuration diagram of the first embodiment of the present invention. The operation of the entire system according to the first exemplary embodiment of the present invention will be described with reference to FIG.

The input image 10 is adjusted to an image having an appropriate light intensity by the diaphragm means 51, and the input image 10 is set at a predetermined mounting angle.
An image is formed on the three-dimensional polarization modulation element 20 by the lens 50,
Written to the device. The two-dimensional polarization modulation element 20 and the predetermined mounting angle when the two-dimensional polarization modulation element 20 is installed will be described subsequently to the entire operation. The linearly polarized read-out light 91 has its traveling direction bent by the semi-transparent mirror 80, and is emitted to the read-out side of the two-dimensional polarization modulation element 20,
Then it is reflected. The polarization state of the reflected two-dimensional optical signal 92 is modulated according to the light intensity distribution of the input image 10. Here, if the polarizing plate 70 is installed at an angle that is orthogonal to the read light 91, the two-dimensional optical signal (polarization) 93 corresponding to the contour of the input image 10 out of the two-dimensional optical signal 92 is generated. Can be extracted. Lens 60
Is for forming the polarized two-dimensional polarized light 93 on the output surface as the output result 30. The control unit 100 includes a two-dimensional polarization modulation element 20 and erasing light and reading light 9 of this element.
1 is controlled.

The input image 10 is a real object illuminated by natural light or laser light, an image displayed on a display element such as a CRT display, and an image displayed on a spatial light modulator such as a liquid crystal panel and illuminated by light. Any image may be used as long as it has a light intensity distribution.

The semi-transparent mirror 80 is one means for making the read light 91 incident on the two-dimensional polarization modulation element 20 and for accurately forming the read result of the two-dimensional polarization modulation element 20 without distortion, and it is also an apparatus. The purpose is to reduce the overall space. The read-out light 91 is incident on the two-dimensional polarization modulation element 20 in an oblique direction, is reflected in the oblique direction, and the semi-transparent mirror 80 is not necessarily required as long as the result can be accurately imaged by the lens 60.

Next, the light intensity distribution state of the input image 10 is converted into a polarization distribution state and is output as two-dimensional light information. A contour extraction method for extracting the boundary of as a contour will be described.

According to the first embodiment of the present invention, as a typical example of a two-dimensional polarization modulation element, a reflection type and photo-addressing type two-dimensional polarization modulation element using a liquid crystal, for example, a reference "Ferroelectricity" by Fukushima et al. Bistable spatial light modulator using liquid crystal ("Bis
table spatial light modulator using a ferroelectri
c liquid crystal ")", Optics Letters, 15, 285 (199
The case of using the ferroelectric liquid crystal spatial light modulator described in (0) will be described. The above-mentioned liquid crystal element is originally manufactured mainly for the purpose of binarizing an image, and is not an element whose polarization modulation characteristic is optimized for contour extraction, but it is actually sufficiently suitable for practical use. In the following, the description of the contour extraction method according to the embodiment of the present invention takes the above liquid crystal element as an example, but the present invention is not limited to this example of the liquid crystal element, and is another element for modulating the polarization state. However, the contour extracting device according to the present invention can be configured.

First, referring to FIG. 3, the two-dimensional polarization modulator 2
The configuration of 0 will be described. The figure shows the structure of a two-dimensional polarization modulator 20 for performing polarization modulation according to the first embodiment of the present invention.

FIG. 3A shows a photoconductive film of amorphous silicon hydroxide (a-Si: HPC), a dielectric mirror (DM), between two sheets of glass coated with a transparent electrode (ITO). Also, the structure of an element sandwiching a ferroelectric liquid crystal (FLC) is shown, and the thickness of each layer is about 1 μm. In FIG. 3A, erasing light and writing light as an input are applied from the left side. On the other hand, the reading light is emitted from the right side, and the result of the reflection is output. Note that this element usually has writing sensitivity in the visible light region, but if the photoconductive film is provided with appropriate characteristics, writing can be performed even in an optical image in the infrared region or the ultraviolet region.

FIG. 3B shows the rubbing direction of the transparent electrode (ITO) in an exaggerated rubbing line when the two-dimensional polarization modulator 20 is viewed from the read side. The rubbing is performed for the purpose of stabilizing the initial state of the liquid crystal. Also, the device is a rectangle suitable for optical image processing applications, and is rubbed at an angle of 22.5 degrees with respect to the sides of the rectangle for maximum use of the effective area. This angle will be described later.

Next, referring to FIG. 4, the two-dimensional polarization modulator 20
The control method of will be described. FIG. 4A shows E,
Electric control pulses given by the control unit 100 for driving the two-dimensional polarization modulation element 20 are shown by using W and R as timings of erasing, writing, and reading, respectively, while FIG. The timing when the unit 100 irradiates the reading light 91 is shown. That is, at timing E, the erasing light is turned on to refresh the element over the front surface, at timing W, writing to the element is performed, and at timing R, the reading light is turned on and the two-dimensional optical information of the element is turned on. Is read. (A) of FIG.
In FIG. 4B, the horizontal axis and the vertical axis represent time and voltage, respectively, and the entire pulse repeats with EW-R as one cycle. The optical pulse modulation of the readout light 91 may be performed by using an acousto-optic device, or a light source 90 may be directly modulated by using a semiconductor laser. As the erasing light, an LED or the like may be used to irradiate the entire surface of the two-dimensional polarization modulation element 20.

When the input image 10 at the time t is written in the two-dimensional polarization modulation element 20, the element holds the image for the time R. Therefore, one cycle of EW-R corresponds to the frame rate of the electrical input means (eg, 1/3
By setting the time shorter than 0 second) and further reducing the width of W, the moving image that changes in real time at the frame rate or less can be used as the input image 10. As a control example, applied voltage V = ± 15 V, E = 300 μs, W =
It can be operated at 200 μs and R = 500 μs, and one cycle in this case is 1 ms. Further, the LED as the erasing light and the acousto-optical element used for the optical pulse modulation of the reading light 91 can be driven at about 5V.

If necessary, one cycle of EW-R can be set to a time longer than the electrical frame rate.

Next, referring to FIG. 5, the two-dimensional polarization modulator 20 is shown.
The operating principle and manufacturing conditions will be described.

FIG. 5A shows the alignment angle of the liquid crystal molecules as seen from the read side of the device, and the read light is assumed to enter from the upper side of the paper surface and be reflected upward again.

First, in the input image 10, the liquid crystal is oriented in the ON (+) direction with respect to the portion where the writing light is present (bright), and conversely, to the portion where the writing light is absent (dark). , The liquid crystal is oriented in the OFF (-) direction. θ _ON , θ _OFF
Are tilt angles of the liquid crystal that are counterclockwise or clockwise with respect to the rubbing direction. The read light is modulated by the effect of the rotation (tilt) of the liquid crystal.

To describe the relationship between the input image and the rotation of the liquid crystal in more detail, as described in the element control method, at the erase timing E in FIG. 4, the liquid crystal on the entire surface of the element is turned off by the irradiation of the erase light and the application of the pulse. Rotated by θ _OFF degree and held as it is. At the next writing timing W, only the liquid crystal in the portion where the writing light is present (bright) due to the application of the writing pulse is rotated by θ _ON degrees in the ON direction and held. Therefore, at the read timing, two states of the OFF direction and the ON direction are read.

In this embodiment, θ _ON is described as counterclockwise rotation and θ _OFF is described as clockwise rotation, but they may be reversed. Actually, when the positive and negative of the pulse shown in (a) of FIG. 4 are reversed and given to the two-dimensional polarization modulation element 20, θ _ON rotates clockwise and θ _ON rotates clockwise.
_{When OFF} is counterclockwise, the read light is modulated.

By the way, the two-dimensional polarization modulator 20 according to the first embodiment of the present invention is of a reflection type, and the reading light is as shown in FIG.
(A) enters the element from the reading surface side, is reflected by the dielectric mirror (DM), and is output, so that it passes through the liquid crystal layer twice. Therefore, the reading light 9
1 is modulated at an angle twice the tilt angle of the liquid crystal. FIG. 5B shows the polarization direction of the light reflected and output by the device.

In FIG. 5B, the read light is linearly polarized light in the horizontal axis direction shown by the Polarizer, and when reading is performed, the vertical axis shown by the analyzer is orthogonal to it. Directional linearly polarized light passes through. That is, the optical system on the read side is set to the crossed Nicols state. The case where the reading-side optical system is set to the parallel Nicol state will be described later. On the other hand, when the reading optical system other than the crossed Nicols and parallel Nicols states is set, the contrast between the contour and other portions becomes low.

In the orthogonal Nicol readout optical system,
Reading light intensity I reflected by_PS ^ON, I_PS ^OFFIs an expression
It is represented by (1) and equation (2). I_PS ^ONHas writing
If I _PS ^OFFIndicates the light intensity when there is no writing light
You

I _PS ^ON = sin ² {2 (θ + θ _ON )} ・ sin ² (2πdΔn / λ) (1) I _PS ^OFF = sin ² {2 (θ-θ _ON )} ・ sin ² (2πdΔn / λ) (2) Here, θ is an angle formed by the rubbing direction of the two-dimensional polarization modulation element 20 and the polarization direction of the read light 91 (an attachment angle of the above-mentioned two-dimensional polarization modulation element 20, and θ is an attachment angle hereinafter). Y), θ _ON and θ _OFF are tilt angles of the ferroelectric liquid crystal with reference to the rubbing direction with and without writing light, d is the thickness of the ferroelectric liquid crystal layer, and Δn
Is the birefringence of the ferroelectric liquid crystal, and λ is the wavelength of the reading light 91. From the equations (1) and (2), the period of I _PS is θ = 9
It can be seen that it is 0 degree.

When the input image 10 is written in the two-dimensional polarization modulation element 20 and the operation of outputting the brightness information of the input image 10 as it is is performed, the two-dimensional polarization modulation element 20 is used.
To get the best contrast and maximum reflectance of
2 (θ + θ _ON ) = 90 degrees, 2 (θ−θ _OFF ) = 0 degrees. Therefore, a liquid crystal with θ _ON = θ _OFF = 22.5 degrees is selected, and λ = 633 nm and Δn = 0. .15,
A device with d = 1 μm was produced, and θ = 22.
5 degrees. This is clear from equations (1) and (2). Note that this θ = 22.5 degrees corresponds to the rubbing direction with respect to the sides of the rectangular element described above.

Next, a method for extracting the contour of the input image 10 using the two-dimensional polarization modulator 20 ideally produced under the above conditions will be described in principle with reference to FIG. 6A to 6G show the input image 10 from the read side of the device.
It is assumed that the reading light 91 is incident from the upper side of the paper surface and is reflected toward the upper side again. FIG. 6A shows the input image 10 in which the left half is bright and the right half is dark.

According to FIG. 6B, the two-dimensional polarization modulator 2
The operation of the 0 liquid crystal will be described. First, the polarization direction of the read light 91 and the rubbing direction of the element are matched. That is, θ = 0 degree is set. When a control pulse is applied to the two-dimensional polarization modulation element 20 in this state, the liquid crystal displays θ _ON degrees (22.5 degrees) in the counterclockwise direction with respect to the (bright) portion where the writing light of FIG. ) Rotate, but for the part where there is no writing light (dark), turn θ _OFF degree (2
2.5 degrees) rotate.

FIG. 6C shows the polarization state of the light that is polarized by the operation of the liquid crystal and is output from the two-dimensional polarization modulation element 20.

The above operation of the liquid crystal can be paraphrased as the modulation state of the read light 91 which is linearly polarized light. That is, as described with reference to FIG. 5B, the reading light 91 that passes through the liquid crystal layer twice is modulated at an angle that is twice the sum or difference of the attachment angle and the tilt angle of the liquid crystal, and is written in the liquid crystal. In the lighted (bright) portion, the polarization _{ON of the} direction in which the polarization direction of the readout light 91 is rotated 2θ _ON degrees (45 degrees) counterclockwise is output. On the contrary, there is no writing light (dark)
For the part, the polarization _{OFF of the} direction in which the polarization direction of the read light 91 is rotated by 2θ _OFF degrees (45 degrees) in the clockwise direction is output. Thus, the read light 9 is included in the two-dimensional optical signal 92.
With respect to one polarization direction, there are portions that are modulated in the polarization direction that forms 2θ _ON degree and 2θ _OFF degree.

Since the two-dimensional polarization modulator 20 has a nonlinear characteristic of ON state and OFF state by polarization modulation, even if the input image 10 is a grayscale image, it is completely binarized except for the contour portion described later. The binarization level may be controlled by the timing of E, W, and R, the applied voltage, or the writing light amount.

By the way, even if the brightness information of the input image 10 is binarized (ON / OFF) depending on the polarization state, the
The polarization output from the liquid crystal of the dimensional polarization modulator 20 or the two-dimensional polarization modulator 20 continuously transitions from OFF to ON at the boundary from the dark portion to the bright portion of the input image 10.
Therefore, the intermediate state indicated by the polarization direction MED in FIG. 6C always exists. Polarization direction MED is polarization O
It appears in the direction of the bisector of the angle formed by the FF direction and the polarization ON direction. The rubbing direction of the liquid crystal and the MED direction ideally match only when 2θ _OFF = 2θ _ON . The MED2 direction of (b) of FIG. 6 shows one type different from the MED direction of the bisector of the angle formed by the polarization OFF direction and the polarization ON direction. The MED2 direction is a bisector direction of the angle formed by the polarization OFF2 direction, which is the opposite direction to the polarization OFF direction, and the polarization ON direction, and is perpendicular to the polarization direction of the readout light 91. This means that from equation (1) and equation (2), I _PS
This corresponds to the cycle of 90 degrees. Polarization direction MED
The intermediate state indicating is intended by blurring the contour portion of the input image 10 by adjusting the control condition of the two-dimensional polarization modulation element 20 or slightly defocusing the image input on the writing side of the two-dimensional polarization modulation element 20. You can also make it.

After all, when the input image 10 shown in (a) of FIG. 6 is written in the two-dimensional polarization modulation element 20, the polarization state becomes the ON state and the OFF state as shown in (c) of FIG.
Furthermore, an intermediate state (MED) having a constant width appears at the boundary. Since the optical system on the read side is in the orthogonal Nicols state as described above, the polarized light in the MED direction is blocked, and finally the black contour image shown in FIG. 6D is obtained.

On the other hand, FIG. 6E is a diagram for explaining the operation of the liquid crystal of the two-dimensional polarization modulator 20 when θ = 45 degrees.

FIG. 6 (f) shows that when the liquid crystal rotation angles θ _OFF and θ _ON are set, as in the case of θ = 0 °, 2
The polarization state of the light output from the dimensional polarization modulator 20 is shown. After all, when the input image 10 shown in FIG. 6A is written in the two-dimensional polarization modulator 20, the polarization state is in the ON state and the OFF state as shown in FIG. An intermediate state (MED) with will appear. Since the optical system on the reading side is in the crossed Nicols state as described above, the polarized light in the MED direction passes, and finally the white contour image shown in FIG. 6G is obtained.

As described above, in the rubbing direction, the rotation θ _ON when there is writing light and the rotation θ when there is no writing light
_As an example, an ideal two-dimensional polarization modulation element 20 having the same direction as _OFF and the same size as _OFF has two polarization angles θ _ON and θ
_The principle that the contour is extracted when _OFF is selected and the polarization direction MED which is an intermediate angle and the rubbing direction are matched with each other has been described.

In FIG. 7, two polarization angles θ _ON and θ _OFF of the two-dimensional polarization modulator 20 are selected according to the first embodiment of the present invention, and a rubbing direction which is an intermediate angle between them is selected for the reading light. The input image 10 of the contour extraction processing set to 0 degree or 45 degrees and the extracted contour image 30 are specifically shown.

The input image 1 is shown in FIGS. 7 (a) and 7 (b).
It is 0, and the bright and dark parts are respectively inverted. When the contour extraction method of the present invention is applied to these images, when the mounting angle θ = 0 degree is applied to any of the input images, as shown in FIG.
A black contour image as shown in FIG. 7C is obtained, while a white contour image as shown in FIG. 7D is obtained when the attachment angle θ = 45 degrees.

The principle of the polarization modulator and the contour extracting method of the contour extracting apparatus according to the first embodiment of the present invention has been described above. Next, each part of the contour extracting apparatus according to the first embodiment of the present invention will be described in detail.

Referring again to FIG. 2, the light source 90 and the light source 9
An image reading unit that extracts linearly polarized light in a specific direction from the light output by 0 will be described.

When the light source 90 outputs random polarized light by white light or random oscillation laser, etc., by installing the polarizing plate 40, only the linearly polarized light forming a specific angle on the plane perpendicular to the traveling direction of light. Just take it out.

On the other hand, when using a light source 90 for generating linearly polarized light such as a gas laser or a semiconductor laser, the light source 90 is set so that the output linearly polarized light makes a predetermined angle in a plane perpendicular to the traveling direction of light. It is not necessary to use the polarizing plate 40. Note that the predetermined angle is, for example, the direction of the polarizer shown in FIG. 5B, as described in the operating principle of the two-dimensional polarization modulation element 20.

The linearly polarized light obtained by either of the above two methods becomes the readout light 91 of the two-dimensional polarization modulator 20.

The optimum wavelength of the read light 91 differs depending on the manufacturing conditions of the two-dimensional polarization modulator 20.
As described in the operation principle of the dimensional polarization modulator 20, for example, a visible light semiconductor laser (wavelength 670 nm), a He-Nc laser (wavelength 633 nm), or the like can be used. Further, in order to synchronize the irradiation timing of the reading light 91 with the reading timing of the two-dimensional polarization modulation element 20, for example, a visible light semiconductor laser is used and the light source 9 is used.
0 may be directly modulated. On the other hand, continuous oscillation He-Ne
When a laser is used, an acousto-optical element or the like may be installed in front of or behind the polarizing plate 40 to modulate the light.

Next, the means for forming the input image 10 on the two-dimensional polarization modulator 20 according to the first embodiment of the present invention will be described. The input image 10 is imaged and written as an image on the two-dimensional polarization modulation element 20 by the imaging lens 50 which is an imaging means. According to the size of the input image 10 and the distance between the input image 10 and the contour extracting device according to the first embodiment of the present invention, the lens 50 having a zoom function and a focusing function, such as moving back and forth in the optical axis direction, The input image 10 is formed as an image of an appropriate size on the writing surface of the two-dimensional polarization modulator 20. In particular, when the input image 10 is a three-dimensional real object having a depth in the optical axis direction, there is also an advantage that the light and dark information of the image in the desired distance range can be clarified by performing focusing using the focusing function. . The lens 50 also includes a diaphragm 51 for adjusting the amount of light for writing in the two-dimensional polarization modulator 20. The diaphragm 51 will be described later.

Next, the polarization modulator according to the first embodiment of the present invention is installed at a predetermined angle with respect to the polarization direction of the read light 91 which is linearly polarized light, writes the input image 10 and outputs the light of the input image 10. The reflection-type and photo-addressing type two-dimensional polarization modulation element 20 modulates the polarization direction of the linearly polarized light on the read side according to the intensity distribution and outputs the polarization distribution state as the two-dimensional light information 92.

Next, an image reading section for realizing the contour extraction according to the first embodiment of the present invention together with the above polarization modulating section will be described. According to the first embodiment of the present invention, for contour extraction, the contour of the input image is optically extracted by setting the two-dimensional polarization modulation element 20 at a predetermined appropriate angle and reading the output of the two-dimensional polarization modulation element 20. To do. Therefore, the image reading unit is configured as follows.

Using the operation of the two-dimensional polarization modulator 20,
In order to output the contour information of the input image 10 as two-dimensional light information, first, the polarization direction of the reading linearly polarized light 91 in FIG. 2 is changed to the polarizer in FIG. 5B.
), And the setting direction of the polarizing plate 70 is set in the same direction as the analyzer, so that the reading optical system has a crossed Nicol configuration. Here, if the attachment angle of the two-dimensional polarization modulation element 20 is set so that the MED direction of the liquid crystal of the two-dimensional polarization modulation element 20 coincides with the polarization direction of the linearly polarized light for reading 91, a black contour appears. In addition, the MED direction of the liquid crystal of the two-dimensional polarization modulation element 20 is set at 45 degrees with the polarization direction of the linear polarization 91 for reading.
If the attachment angle of the dimensional polarization modulator 20 is set, a white outline appears.

On the other hand, when the reading optical system has a parallel Nicol structure, the two-dimensional polarization modulation element 20 is attached so that the MED direction of the liquid crystal of the two-dimensional polarization modulation element 20 matches the polarization direction of the linear polarization 91 for reading. If you set the angle, a white outline will appear. Further, the MED direction of the liquid crystal of the two-dimensional polarization modulation element 20 is 4
If the attachment angle of the two-dimensional polarization modulation element 20 is set so as to form 5 degrees, a black contour appears.

By configuring the image reading unit to have a crossed Nicols or parallel Nicols configuration, the contrast of the brightness and darkness of the contour image 30 output is maximized.

According to the first embodiment of the present invention, the input image 10
The polarized image output unit that forms and outputs the contour image extracted from the above will be described.

According to the first embodiment of the present invention, two contour extraction methods are realized by the method of constructing the optical system of the image reading section. In any case, the width of the extracted contour component is the width of the polarization component in the MED direction, and is uniform over the entire input image 10 to be input.

After all, the two-dimensional optical signal 92 whose polarization state is modulated by the two-dimensional polarization modulation element 20 according to the light intensity distribution of the input image 10 passes through the semi-transparent mirror 80, and a part of it is in the polarizing plate 70. And an image forming lens 6 which is an image forming means.
A desired contour image signal 93 is imaged by 0 and output result 3
0 is obtained. Either the polarizing plate 70 or the imaging lens 60 may be installed first.

The image input unit of the contour extracting apparatus according to the first embodiment of the present invention will be described.

As shown in FIG. 2, the image input section includes an iris diaphragm 51 for adjusting the light intensity of the input image 10 and a lens 5 for forming the input image 10 on the two-dimensional polarization modulator 20.
It consists of 0 and.

The adjustment of the input image light will be described with reference to FIG. As a means for adjusting the brightness of the input image 10 that is the target of contour extraction, that is, the light intensity of the input image 10, for example, the iris diaphragm 51 can be used. When the light intensity of the input image 10 is changed by adjusting the iris diaphragm 51, the contour image extracted from the input image 10 changes accordingly. Therefore, while observing the output result 30 of the contour extraction processing, the iris diaphragm 5 is adjusted so that a desired light intensity can be obtained.
1 can be adjusted appropriately.

When the diaphragm 51 is opened, the two-dimensional polarization modulation element 20
The amount of light radiated on the screen increases, and the bright part of the input image becomes brighter, and an image with high contrast can be obtained. When an image containing such strong light is incident,
Light is diffused on the light-receiving surface side of the two-dimensional polarization modulation element 20, and the two-dimensional polarization modulation element 20 gives the same result as the response to the bright part even in the dark part having a small area among the elements constituting the image. Output. Therefore, it is possible to extract the contour of the portion of the image where the difference in lightness and darkness is most noticeable, and to remove fine noise and the like in the image.

The result of contour extraction by adjusting the light intensity of the input image will be described in detail with reference to FIG. First, a grayscale image as shown in FIG. 12A or 12B is input to the contour extracting apparatus according to the first embodiment of the present invention. In the figure, the shaded areas are the bright areas (white) and the dark areas (black).
And represents the halftone. 12 (c) and 12 (e) use an image reading unit having an orthogonal Nicol configuration, and FIGS. 12 (d) and 12 (f) use an image reading unit having a parallel Nicol configuration to perform contour extraction processing. It is carried out.

When the iris diaphragm 51 is opened, the contour of the portion where the difference in brightness from the background is most remarkable is extracted as shown in FIG. 12 (e) or FIG. 12 (f). On the other hand, the iris diaphragm 5
In the state where 1 is slightly squeezed, (c) of FIG.
The contour of the halftone portion in the input image is extracted in addition to the portion where the difference in brightness is remarkable as shown in (d).

It is convenient that the iris diaphragm 51 is incorporated in the lens 50, for example, and a normal camera lens can be used as this example.

Next, the adjustment of the depth of focus according to the first embodiment of the present invention will be described. If the input image 10 is a three-dimensional real object, or if a plurality of objects are image input lens 5
The numerical aperture of the lens 50 (N
The distance range in which the contour is extracted can be adjusted by adjusting the depth of focus (± λ / 2 (NA) ² ) determined by A) and the wavelength (λ) of incident light that carries the input image 10.

When the depth of focus is shallow, the distance range between the object input as an image and the device is narrow, and it can be regarded as a surface at a specific distance from the device. That is, it is possible to clearly extract the contour image in the two-dimensional plane located at the specific distance from the contour extracting device according to the first embodiment of the present invention. Furthermore, this feature can also provide distance information between the target object and the device.

On the other hand, when the depth of focus is deep, an image of an object located in a wide distance range can be obtained as an input image.

Further, the focus adjustment according to the first embodiment of the present invention will be described. By adjusting the focus, the accuracy of the extracted contour line changes. When the input image 10 is focused on the two-dimensional polarization modulation element 20 and focused, a strict thin contour line is obtained as a result of the contour extraction processing. on the other hand,
If an image is formed on the object without completely matching the focus, the contour line of the contour extraction result becomes thick and the observation becomes easy. Further, details are excluded from the strict contours of the image, and the contours of typical portions that make up the input image are emphasized.

With reference to FIG. 13, the effect of the focus adjustment according to the first embodiment of the present invention on the contour extraction result will be described. (A) and (b) of the figure show the input image,
(C), (d), (e) and (f) show output images of contour extraction. Specifically, the focus is adjusted by adjusting the focus of the lens 50 shown in FIG.

The image shown in FIGS. 13A and 13B is input to the contour extracting apparatus according to the first embodiment of the present invention so that the two-dimensional polarization modulator 20 is completely focused. The results of the contour extraction processing when an image is formed are shown in FIGS. 13C and 13D, respectively. The contour line of the contour image as the processing result is extracted as a thin line having a sufficiently high contrast with the background portion.

On the other hand, the input image of FIG. 13A and FIG.
FIG. 13E shows the result of the contour extraction processing when (b) of 3 is imaged on the two-dimensional polarization modulator 20 with a slight defocus.
13 (f), respectively. The contour line of the contour image as the processing result is extracted as a thick halftone line. In the figure, the shaded areas are the bright areas (white) and the dark areas (black).
And represents the halftone part. The contrast of the thick contour line with respect to the other portions is lower than that in (c) of FIG. 13 and (d) of FIG. 13, but the visibility is excellent because the contour line is thick. Further, although not shown in the figure, details are removed from the outline of the image, and the outline of a typical portion forming the input image is emphasized.

Next, the contour extracting device according to the present invention extracts a clear contour of the input image 10 even when the two-dimensional polarization modulator 20 used for polarization modulation is not an ideal two-dimensional polarization modulator. This will be described in detail with reference to the first embodiment of the present invention.

The principle of the above-mentioned contour extraction is that the liquid crystal in the two-dimensional polarization modulation element 20 is symmetrically rotated by 22.5 degrees from the rubbing direction to the clockwise direction or the counterclockwise direction. The dimensional polarization modulator 20 has been described as modulating the polarization direction of the readout light 91, outputting polarization OFF, polarization ON in a direction forming an angle of 90 degrees with the polarization OFF, and further outputting the intermediate state MED.

The angle between the polarization ON and the polarization OFF
Of the readout light 91, which is linearly polarized in the direction of the bisector of
A black outline is obtained by matching the direction, while the polarization is ON.
Read out the bisector of the angle between
White when set at an angle of 45 degrees to the polarization direction of 91
It is shown that the contour can be obtained. Furthermore, ideally, θ
_OFF= Θ_ONOf the two-dimensional polarization modulation element 20
Match the rubbing direction with the polarization direction of the reading light 91.
And a black contour is obtained, while the two-dimensional polarization modulator 20
The rubbing direction is 45 with respect to the polarization direction of the reading light 91.
You can obtain a white outline by setting the angle in degrees.
I also mentioned how to get out.

The liquid crystal rotation angle is symmetrically θ from the rubbing direction in the clockwise direction or the counterclockwise direction.
_OFF degree, θ _ON degree (Angle other than 22.5 degrees, eg 20
2) and the two-dimensional polarization modulation element 20 is relatively 2
A two-dimensional polarization modulator 20 that outputs polarized light OFF and polarized light ON at an angle of (θ _OFF + θ _ON ) degrees (80 degrees in this case).
Alternatively, even when the control condition is used, the above contour extraction method is applied, and the first embodiment of the present invention can be applied.

However, the above method can be explained only under the ideal modulation element or modulation condition that the rubbing direction of the two-dimensional polarization modulation element 20 and the polarization direction of the intermediate state MED are the same. That is, the liquid crystal rotation angle is asymmetrically θ _OFF from the rubbing direction to the clockwise or counterclockwise direction.
Degrees, rotated theta _ON degrees two-dimensional polarization polarization OFF and the polarizing O modulation element 20 forms an angle relatively 2 (θ _OFF + θ _ON) of
When N is output, a black outline is not obtained even if the rubbing direction of the two-dimensional polarization modulation element 20 is made to match the polarization direction of the read light 91, while the rubbing direction of the two-dimensional polarization modulation element 20 is changed. Even if it is set at an angle of 45 degrees with respect to the polarization direction of the reading light 91, a white outline is not obtained. This means that the maximum value of the rotation angle of the two-dimensional polarization modulation element 20 changes according to the product of the voltage value and the pulse width of the erase and write pulses applied to the two-dimensional polarization modulation element 20 shown in FIG. to cause. That is, when the energy given to the element is insufficient, the maximum value of the rotation angle of the element does not reach the predetermined rotation angle in the saturated state.
This has been confirmed experimentally. Therefore,
The general method for obtaining the contour image and the control conditions of the element will be described in detail below.

First, the actual characteristics of the two-dimensional polarization modulation element 20 and the contour extraction method when using it will be described.

In the actual two-dimensional polarization modulator 20, it has been confirmed by actual measurement that the rotation angle of the liquid crystal is asymmetrically θ _OFF degree and θ _ON degree from the rubbing direction to the clockwise direction or the counterclockwise direction, respectively.

The output result when the polarization direction of the reading light 91 and the rubbing direction are matched with each other by using the actual two-dimensional polarization modulator 20 in which the rubbing direction and the MED direction do not match will be specifically described with reference to FIG. This is an explanation of an example in which a desired contour image cannot be obtained.

In FIGS. 8A to 8G, θ _ON = 5.
When 5 ° and θ _OFF = 21.5 °, the polarization direction of the reading light 91 and the rubbing direction are matched, that is, θ
The output and the like in the case of = 0 degree are shown. This figure shows
Corresponding to FIG. 6 shown in the case of an ideal element, a portion with writing light (bright) is white, and there is no writing light (dark).
Parts are shown in black, and halftones are shown in diagonal lines. The shaded area including both the left-downward and the right-downward indicates a darker halftone as compared to the diagonally-downward area only for the left-down.

As shown in (b) of FIG. 8, the liquid crystal is rotated in the counterclockwise direction by θ _ON degree (5.5 degrees) with respect to the (bright) portion where the writing light is present in (a) of FIG. However, on the other hand, for the part where there is no writing light (dark), θ is turned clockwise.
_It turns _OFF (21.5 degrees). FIG. 8C is a diagram illustrating a polarization state output from the two-dimensional polarization modulation element 20. As described with reference to FIG. 5B, the read light 91 is modulated at an angle that is twice the sum or difference of the mounting angle and the tilt angle of the liquid crystal, so that the writing light (bright) portion is , And outputs polarization _ON in the direction in which the polarization direction of the reading light 91 is rotated 2θ _ON degrees (11 degrees) counterclockwise. On the other hand, with respect to a portion where there is no writing light (dark), the polarization _{OFF of the} direction in which the polarization direction of the reading light 91 is rotated by 2θ _OFF degrees (43 degrees) in the clockwise direction is output.

In addition, in FIG. 8B, the polarization direction ME
The intermediate state indicated by D always exists. The polarization direction MED appears in the bisector direction of the angle formed by the polarization OFF direction and the polarization ON direction. In this description, since 2θ _OFF ≠ 2θ _ON , the MED direction and the rubbing direction do not match.

When the input image 10 shown in FIG. 8A is written in the two-dimensional polarization modulator 20, the polarization state is as shown in FIG.
As shown in (c), the ON state and the OFF state, and the intermediate state (MED) having a constant width appears at the boundary. Since the optical system on the reading side is in the crossed Nicols state as described above, the polarized light in the rubbing direction is blocked and becomes a dark state, but the final output is a black outline as shown in (d) of FIG. In addition to the image, a halftone part is included.

On the other hand, FIG. 8E is a diagram for explaining the operation of the liquid crystal of the two-dimensional polarization modulation element 20 when θ = 45 degrees. The rotation angle of the liquid crystal is the same as in the case of θ = 0 degree, and the polarization state of the light output from the two-dimensional polarization modulation element 20 is shown in (f) of FIG. Here, when the input image 10 shown in (a) of FIG. 8 is written in the two-dimensional polarization modulation element 20, the polarization state is as shown in (f) of FIG. An intermediate state (MED) with width will appear. Since the optical system on the read side is in the crossed Nicols state as described above, polarized light in the rubbing direction passes and becomes bright, but the final output is bright as shown in FIG. In addition to the contour image, a halftone portion is included.

As described above, in the actual two-dimensional polarization modulator 20, when the rubbing direction and the MED direction do not match, the angle formed by the polarization direction of the read light 91 and the rubbing direction is 0 degree or 45 degrees. It was shown that the desired contour extraction performance could not be obtained even when set to.

Next, according to the first embodiment of the present invention, by using an actual element in which the rubbing direction and the MED direction do not match, a desired contour image can be obtained by matching the polarization direction of the reading light and the MED direction. Will be specifically described.

In FIGS. 9A to 9G, θ _ON = 5.
When 5 ° and θ _OFF = 21.5 °, the polarization direction of the read light 91 and the MED direction are matched, that is, θ =
In the case of 8 degrees, and the polarization direction of the reading light 91 and the ME
When the angle formed by the D direction is 45 degrees, that is, θ
The following shows the result of contour extraction when = 53 degrees. This figure corresponds to FIGS. 6 and 8. The shaded portion in the figure indicates that the halftone is between the bright portion shown in white and the dark portion shown in black.

As shown in (b) of FIG. 9, the liquid crystal is rotated in the counterclockwise direction by θ _ON degrees (5.5 degrees) with respect to the (bright) portion where the writing light is present in (a) of FIG. However, on the other hand, for the part where there is no writing light (dark), θ is turned clockwise.
_It turns _OFF (21.5 degrees). FIG. 9C is a diagram illustrating the polarization state output from the two-dimensional polarization modulation element 20. As described with reference to FIG. 5B, the read light 91 is modulated at an angle that is twice the sum or difference of the mounting angle and the tilt angle of the liquid crystal, so that the writing light (bright) portion is , And outputs polarization _ON in the direction in which the polarization direction of the read light 91 is rotated counterclockwise by 2 (θ + θ _ON ) degrees (27 degrees). On the other hand, the polarization direction of the reading light 91 is set to 2 clockwise with respect to the portion where the writing light is not present (dark).
(Θ-θ _OFF ) degrees (27 degrees) Polarization OFF in the rotated direction
Is output.

Further, in FIG. 9B, the polarization direction ME
The intermediate state indicated by D always exists. The polarization direction MED appears in the bisector direction of the angle formed by the polarization OFF direction and the polarization ON direction. Since 2θ _OFF ≠ 2θ _ON in this description, the MED direction and the rubbing direction do not match.

After all, when the input image 10 shown in FIG. 9A is written in the two-dimensional polarization modulation element 20, the polarization states are the ON state and the OFF state as shown in FIG. 9C.
Furthermore, an intermediate state (MED) having a constant width appears at the boundary. Since the optical system on the readout side is in the orthogonal Nicols state as described above, the polarized light in the MED direction is blocked and becomes a dark state, and the final output of the contour extraction result is as shown in (d) of FIG. Only the black outline image is available.

On the other hand, in (e) of FIG. 9, θ = 53 (= 45
The operation of the liquid crystal of the two-dimensional polarization modulation element 20 at +8) degrees is shown. The rotation angle of the liquid crystal is the same as in the case of θ = 8 degrees, and the polarization state of the light output from the two-dimensional polarization modulation element 20 is the state shown in (f) of FIG. After all, when the input image 10 shown in (a) of FIG. 9 is written in the two-dimensional polarization modulator 20, the polarization state becomes (f) of FIG.
As described above, an ON state and an OFF state, and an intermediate state (MED) having a constant width appears at the boundary. Since the optical system on the reading side is in the crossed Nicols state as described above,
The polarized light in the MED direction passes and becomes a bright state, and the final contour extraction result output is only the bright contour image as shown in (g) of FIG.

Next, when the actual two-dimensional polarization modulator 20 is used, the rotation angle of the liquid crystal is symmetrically _turned clockwise or counterclockwise with respect to the rubbing direction by θ _OFF degree,
A case will be described in which the contrast of the extracted contour is low even though the degree becomes θ _ON degree.

As a result of actual measurement, when the applied voltage is about ± 7 V, I _PS ^ON has a minimum at θ = −7.5 degrees, and I _PS ^OFF has a minimum at θ = 7.5 degrees. That is, θ _ON = θ _OFF = 7.5 degrees only in the case of this specific voltage, and the rotation angle of the liquid crystal is symmetric. However, the reading light 91
A black contour image is obtained when the rubbing directions of the element liquid crystal and the rubbing direction are matched, but sufficient contrast cannot be obtained. This will be described from the measured data.

In FIG. 10, the rotation angle of the liquid crystal is θ._ON= Θ
_OFF= 7.5 degrees, θ and I_PS ^ON, And θ and I_PS
^OFFThe result of having measured the relationship of is shown. The side of (a) of FIG.
The axis is the mounting angle θ [unit: degree], and the vertical axis is the two-dimensional polarization modulator
Reflected light intensity I of child 20_PS ^ON, I _PS ^OFF[Unit: Light intensity
Arbitrary unit]. However, the measured value is analyzed numerically
In order to perform
Are omitted.

The approximation is performed by the following method. The expressions (1) and (2) described above are expressed by the expression (3) with A and B as constants.
And can be replaced by equation (4).

I _PS ^ON = A _ON + B _ON · sin ² {2 (θ + θ _ON )} (3) I _PS ^OFF = A _OFF + B _OFF · sin ² {2 (θ−θ _OFF } (4) From this, A _ON = A _OFF = 0.2, B _ON = B _OFF = 5.
It is calculated as 0. As can be easily considered from equations (3) and (4), since the I _PS cycle is 90 [degrees], (a) of FIG. 10 shows a range of 0 ≦ θ ≦ 90 [degrees]. It is drawn with.

By the way, when θ _ON = θ _OFF = 7.5 degrees, from the value of I _PS ^ON = I _PS ^{OF F according} to the above description, θ
A black contour appears at = 0 degrees, and a white contour appears at θ = 45 degrees. However, when θ _ON = θ _OFF = 7.5 degrees, there is a problem that the contrast between the contour line and other portions is low.

The contrast between the contour line and the surrounding portion can be specifically read from FIG. 10 as follows. θ = 0 ° --Light intensity of black contour: ambient light intensity = 0.
2: 0.5 = 1: 2.5 θ = 45 degrees-light intensity of white contour: ambient light intensity = 5.
2: 4.9 = 1.06: 1 Therefore, even if the rubbing direction of the two-dimensional polarization modulation element 20 and the polarization direction of the read light 91 are matched, or 2
The rubbing direction of the three-dimensional polarization modulator 20 is read out by the light 91.
Even if it is set to 45 degrees with respect to the polarization direction, a clear contour cannot be obtained with the above contrast.

Next, according to the first embodiment of the present invention, even if the rotation angle of the liquid crystal is asymmetrical in the clockwise direction or the counterclockwise direction with respect to the rubbing direction, respectively, θ _OFF degree and θ _ON degree, a high contrast is obtained. Explain that the contour can be extracted.

In FIG. 11, the rotation angle of the liquid crystal is θ _ON = 5.
The results obtained by actually measuring the relationship between θ and I _PS ^ON , and θ and I _PS ^OFF when 5 degrees and θ _OFF = 21.5 degrees are shown. The view of the figure is based on FIG. As a result, A _ON = A _OFF = 0.
15, B _ON = B _OFF = 5.05.

By the way, θ _ON = 5.5 degrees, θ _OFF = 21.5
In the case of degrees, a black contour appears at θ = 8 degrees and a white contour appears at θ = 53 degrees from the value of I _PS ^ON = I _PS ^OFF . Next, the contrast between the contour line and its surrounding portion can be read from FIG. 11 as follows. θ = 8 degrees--Light intensity of black contour: Ambient light intensity = 0.1
5: 1.3 = 1: 8.7 θ = 53 degrees-white contour light intensity: ambient light intensity = 5.0
5: 4.1 = 1.3: 1 Therefore, if the MED direction of the two-dimensional polarization modulation element 20 and the polarization direction of the read light 91 are matched, a clear contour can be obtained.

From the above description, the outline extraction processing according to the present invention can be summarized into the following three points.

The two-dimensional polarization modulation element 20 is used for the input image 10
For the portion with light (bright), the polarization direction of the reading light is rotated clockwise in the ON state, while for the portion without light (dark), the polarization direction of the reading light 91 is turned on. O in the counterclockwise direction, which is the opposite direction to the state
The two-dimensional light information 9 is rotated by rotating as an FF state, converting the distribution state of the light intensity of the input image 10 into the distribution state of the polarization direction.
Output as 2.

With respect to the attachment angle of the two-dimensional polarization modulator 20, the bisector direction of the angle formed by the polarization direction in the ON state and the polarization direction in the OFF state is made to coincide with the polarization direction of the read light 91, thereby inputting. The light and dark boundaries of the image are extracted as black contours.

Further, by setting the bisector direction of the angle formed by the polarization direction in the ON state and the polarization direction in the OFF state at an angle of 45 degrees from the polarization direction of the read light 91, the bright / dark boundary of the input image 10 is set. Is extracted as a white contour.

Up to this point, in the first embodiment of the present invention, the optical system of the image reading section is explained as a crossed Nicols, but the optical system of the image reading section of the present invention is limited to the crossed Nicols state. It is shown below that it also includes a parallel Nicol state.

In FIG. 5B, it is assumed that the readout light 91 is linearly polarized light in the direction of the horizontal axis shown by the Polarizer, and an optical system through which linearly polarized light in the same direction passes during reading. Think That is, the optical system on the read side is set in the parallel Nicol state.

In the parallel Nicol read-out optical system, the read-out light intensities I _PS ^ON and I _PS ^OFF reflected by the two-dimensional polarization modulator 20 are expressed by formulas (1) and (2) obtained by shifting the phase by 45 degrees. 5) and the formula (6). I _PS ^ON shows the light intensity when there is writing light, and I _PS ^OFF shows the light intensity when there is no writing light. I _PS ^ON = sin ² {2 (θ + 45 + θ _ON )} ・ sin ² (2πdΔn / λ) (5) I _PS ^OFF = sin ² {2 (θ + 45−θ _ON )} ・ sin ² (2πdΔn / λ) (2) Symbols such as θ are the same as those in Expressions (1) and (2).

From the value of I _PS ^ON = I _PS ^OFF , for example, in the example of the numerical values described above, θ _ON = 5.5 degrees, θ _OFF = 2
In the case of 1.5 degrees, a white outline appears at θ = 8 degrees,
A black contour appears at θ53 degrees.

Finally, of the two-dimensional polarization modulators 20 used for contour extraction, the ones with high contrast ratio are
This is an element in which the liquid crystal rotates 45 degrees clockwise or counterclockwise from the initial direction, and accordingly, the relative angle between the polarization OFF and the polarization ON that is output is 180 degrees.
Even in such an element, the above-mentioned polarized MED always exists, and therefore the contour extraction method of the present invention is effective.

The second embodiment of the present invention will be described below with reference to FIG. The second embodiment of the present invention is characterized in that the optical system of the image reading section forms a crossed Nicols with a polarization beam splitter. On the other hand, the first embodiment of the present invention constitutes an optical system in a crossed Nicols state or a parallel Nicols state by combining a polarizing plate and a semi-transparent mirror. In view of the above points, the optical system of the image reading unit, which is a feature of the second embodiment, will be described in detail.

FIG. 14 shows the system configuration of the second embodiment of the present invention. First, the operation of the entire system will be described with reference to FIG.

The input image 10 is adjusted to an image having an appropriate light intensity by the diaphragm means 51, and is set at a predetermined mounting angle.
An image is formed on the dimensional polarization modulation element 20 by the lens 50 and written in the element. The predetermined mounting angle when installing the two-dimensional polarization modulator 20 is the same as the mounting angle of the first embodiment. On the other hand, the light output from the light source 90 is bent in the traveling direction by the polarization beam splitter 81 and is converted into linearly polarized light. The light is emitted as the reading light 91 to the reading side of the two-dimensional polarization modulation element 20, and is then reflected. The polarization state of the reflected two-dimensional optical signal 92 is modulated according to the light intensity distribution of the input image 10.

The image reading section in FIG. 14 constitutes a crossed Nicols using a polarization beam splitter 81. Therefore, from the two-dimensional optical signal 92, the two-dimensional optical signal (polarization) 93 corresponding to the contour of the input image 10 can be extracted. The lens 60 forms an image of the two-dimensional optical signal (polarized light) 93 on the output surface as the output result 30. Control unit 100
Is for controlling the two-dimensional polarization modulation element 20, erasing light of the element, and reading light 91.

The type of the input image 10 may be any image as long as it has the light intensity distribution, as described in the first embodiment. The means for forming the input image 10 on the two-dimensional polarization modulator 20 is also the same as in the first embodiment.

Further, the means for adjusting the light intensity, the depth of focus and the focus of the input image 10 are the same as in the first embodiment.

Next, a light source for image reading according to the second embodiment of the present invention and an image reading section for extracting linearly polarized light in a specific direction from the light output from the light source will be described.

The polarization beam splitter 81 transmits P-polarized light of the polarized component of light, reflects S-polarized light which is orthogonal to the P-polarized light, and bends the traveling direction. It is sufficient to extract linearly polarized light in a specific direction by utilizing this property.

When the light source 90 outputs white light or random polarized light by a random oscillation laser or the like, it is reflected by the polarization beam splitter 81 and, in a plane perpendicular to the traveling direction of light, a linearly polarized component in the horizontal direction, that is, , S-polarized light is extracted as the reading light 91.

On the other hand, when a light source 90 for generating linearly polarized light such as a gas laser or a semiconductor laser is used, the angle of the light source 90 is adjusted so that the outputted linearly polarized light becomes S polarized light on a plane perpendicular to the traveling direction of light. If set, the amount of read light 91 becomes maximum.

The linearly polarized light obtained by either of the above two methods becomes the readout light 91 of the two-dimensional polarization modulation element 20.

The wavelength of the read light 91 is optimally selected according to the manufacturing conditions of the two-dimensional polarization modulation element 20. The irradiation timing of the two-dimensional polarization modulation element 20 may be the irradiation light directly or the acousto-optic element. As described in the first embodiment, the data is modulated and synchronized by the above. On the other hand, the polarization beam splitter 81 is an optimum polarization beam splitter 8 corresponding to the selected wavelength of the readout light 91.
It is necessary to use 1.

Next, a polarization modulator for extracting a contour image according to the second embodiment of the present invention will be described. As in the first embodiment, the two-dimensional polarization modulation element 20 for polarization modulation is used.
To use.

Further, in the second embodiment of the present invention, as in the first embodiment, the two-dimensional polarization modulation element 20 is set to a predetermined angle, and the output of the two-dimensional polarization modulation element 20 is extracted. The contour information of the input image 10 is extracted by the means.

The contour information of the input image 10 is output as the two-dimensional light information 92 by using the operation of the above two-dimensional polarization modulator 20. First, the polarization direction of the readout linearly polarized light 91 in FIG. 14 matches the direction (S-polarized light) of the polarizer (Polarizer) in FIG. 5B by the polarization beam splitter 81. The reading optical system has a crossed Nicol configuration. In this state, the attachment angle of the two-dimensional polarization modulation element 20 is set so that the MED direction of the liquid crystal matches the polarization direction of the read linearly polarized light 91. As a result, the optical signal of the contour image component of the input image 10 is polarized in the same direction as the read linearly polarized light 91. Therefore, when the two-dimensional optical signal 92 reflected by the two-dimensional polarization modulator 20 enters the polarization beam splitter 81, the two-dimensional optical signal 9
The second S-polarized light (direction of Polarizer) does not pass through the polarization beam splitter 81, so that a black contour is extracted. Also,
If the mounting angle of the two-dimensional polarization modulation element 20 is set so that the liquid crystal MED direction makes 45 degrees with the polarization direction of the linearly polarized light 91 for reading, the two-dimensional polarization modulation element 20 is modulated.
The P-polarized light of the dimensional signal 92 passes through the polarization beam splitter 81, and a white outline is extracted.

However, since the optical system of the reading section according to the second embodiment of the present invention uses the polarization beam splitter 81, it does not form a parallel Nicol state. Therefore, contour extraction using the parallel Nicols state is not performed.

The image formation of the extracted contour image according to the second embodiment of the present invention is performed by the lens 60 as in the first embodiment of the present invention.
It is realized by.

Finally, a third embodiment of the present invention will be described in detail with reference to the drawings. A feature of the third embodiment of the present invention is that the transmission type two-dimensional polarization modulator 21 is used for polarization modulation.

FIG. 15 is a system configuration diagram of the third embodiment of the present invention, and the entire apparatus will be described with reference to the same diagram.

The input image 10 is imaged by the lens 50 on the two-dimensional polarization modulation element 21 installed at a predetermined angle and written in the two-dimensional polarization modulation element 21. The predetermined angle when the two-dimensional polarization modulation element 21 is installed will be described later. On the other hand, the linearly polarized read light 91 is transmitted to the two-dimensional polarization modulation element 21 after being irradiated. Transparent 2
The polarization state of the three-dimensional optical signal 92 is modulated according to the light intensity distribution of the input image 10. The polarizing plate 70 is installed so as to extract a polarization state (two-dimensional optical signal 93) having a constant width corresponding to the contour information of the image from the two-dimensional optical signal 92. The lens 60 images the two-dimensional optical signal 93 on the output result surface 30. The control unit 100 uses the two-dimensional polarization modulation element 21.
And control the reading light 91.

Further, in FIG. 15, the read light 91 is incident from the same direction as the input image 10 with respect to the two-dimensional polarization modulator 21, but it may be incident from the opposite direction.

The type of the input image 10 may be any image as long as it has the light intensity distribution, as described in the first embodiment. The means for forming the input image 10 on the two-dimensional polarization modulator 20 is also the same as in the first embodiment.

Further, the means for adjusting the light intensity, the depth of focus and the focus of the input image 10 are the same as in the first embodiment.

Next, the light source 90 and means for extracting linearly polarized light in a specific direction from the light output from the light source 90 will be described.

When the light source 90 outputs white light or random polarized light such as random direction oscillation laser, the polarizing plate 40 is installed so that the linearly polarized light 91 forms a specific angle in a plane perpendicular to the light traveling direction. Just take out. This angle will be described in the operating principle of the two-dimensional polarization modulator 21.

On the other hand, when a light source 90 for generating linearly polarized light such as a gas laser or a semiconductor laser is used, the light source 90 is set so that the output linearly polarized light makes a specific angle on a plane perpendicular to the traveling direction of light. If so, the polarizing plate 40 is not necessary.

The linearly polarized light obtained by either of the above two methods becomes the readout light 91 of the two-dimensional polarization modulation element 21.

Next, the input image is written at a predetermined angle with respect to the polarization direction of the linearly polarized light, and the polarization direction of the linearly polarized light on the read side is modulated according to the light intensity distribution of the input image. A transmissive and optically addressable two-dimensional polarization modulator 21 according to the third embodiment of the present invention, which outputs three-dimensional light information, will be described.

Here, a modulation element using liquid crystal will be described as a typical example, but the present description is applicable to any element as long as it modulates the polarization state.

The control method of the two-dimensional polarization modulator 21 is the same as the control of the two-dimensional polarization modulator 20 according to the first embodiment of the present invention.

Next, the operation of the two-dimensional polarization modulator 21 will be described. The reading light 91 is the two-dimensional polarization modulation element 21.
Through. The transmitted two-dimensional optical signal 92 is the input image 1
The polarization state is modulated according to the light intensity distribution of 0. The above will be described in detail with reference to FIG.

16A to 16H are described in a state where the direction of the light source 90 is seen from the output result surface 30.
16A shows the input image 10 in which the left half is bright and the right half is dark. FIG. 16B is a diagram for explaining the operation of the liquid crystal of the two-dimensional polarization modulation element 21.

The alignment direction of the liquid crystal when no control pulse is applied to the two-dimensional polarization modulator 21 is the initial direction of the liquid crystal. When a control pulse is given, the liquid crystal in the two-dimensional polarization modulator 21 has no writing light (dark) in FIG.
For the part, it is rotated by θ degrees (here, 45 degrees) from the initial direction to the clockwise direction, while for the part where the writing light is (bright), it is rotated from the initial direction to the counterclockwise direction by θ degrees ( Here, it is set to 45 degrees).

FIG. 16C shows the two-dimensional polarization modulator 2
It is a figure explaining the polarization modulation state of No. 1.

In other words, the operation of the liquid crystal is rephrased as the modulation state of the linearly polarized light 91, and the two-dimensional polarization modulation element 21 has a reading light for a portion where there is no writing light (dark) in FIG. Polarization OF in the same direction as the polarization direction of 91
Output F. On the other hand, in the portion where the writing light is (bright), the polarization ON of the direction in which the polarization direction of the reading light 91 is rotated by 2θ degrees (here, 90 degrees) is output counterclockwise. That is, in the two-dimensional optical signal 92, a portion that is not different from the polarization direction of the read light 91, and that and 2θ
There is a portion which is modulated in the direction of polarization.

Since the two-dimensional polarization modulation element 21 has a non-linear characteristic of ON state and OFF state due to polarization modulation, even if the input image 10 is a grayscale image, it is completely 2
Valued. The binarization level may be controlled by the timings of E, W, and R, the applied voltage, or the writing light amount. This is the same as the two-dimensional polarization modulator 20 according to the first embodiment of the present invention.

By the way, depending on the polarization state, binarization (ON
/ OFF), in the actual two-dimensional polarization modulation element 21, the OF is continuously turned off at the boundary between the bright and dark parts of the input image 10.
Transition from F to ON. Therefore, there always exists the intermediate state indicated by the polarization direction MED. The polarization direction MED appears in the bisector direction of the angle formed by the polarization OFF direction and the polarization ON direction, and coincides with the initial direction of the liquid crystal. This intermediate state is 2
It can also be intentionally created by a control condition of the dimensional polarization modulator 21 or a method such as a slight defocusing by the image forming means on the writing side. This is the same as the two-dimensional polarization modulator 20 according to the first embodiment of the present invention.

After all, when the input image 10 shown in (a) of FIG. 16 is written in the two-dimensional polarization modulation element 21, the polarization state becomes the ON state and the OFF state as shown in (d) of FIG. An intermediate state (MED) with a constant width will appear.

An optical means for extracting the contour of the input image 10 from the predetermined angle of the two-dimensional polarization modulation element 21 and the output of the two-dimensional polarization modulation element 21 according to the third embodiment of the present invention will be described.

In order to output the contour information of the input image 10 as two-dimensional light information by using the operation of the above two-dimensional polarization modulator 21, first, the polarization direction of the read linearly polarized light 91 in FIG. 16 (b), the two-dimensional polarization modulation element 21 may be installed such that it is aligned with the OFF direction and the initial direction of the liquid crystal, that is, the MED direction is the vertical direction in FIG. 16 (d). . These are the measures to maximize the contrast of the light and dark of the output 30.

FIG. 16E shows the setting direction of the polarizing plate 70, and in FIG. 16E, it is described that polarized light in the vertical direction (MED direction) is passed. The result obtained by passing the polarizing plate 70 in the state of (e) of FIG. 16 to the output of (d) of FIG. 16 which is the two-dimensional optical signal 92 is (f) of FIG. 16 and only the contour component is obtained. Appears in a bright state. On the other hand, FIG.
(G) indicates the setting direction of the polarizing plate 70, and it is described that the polarized light in the lateral direction (direction perpendicular to the MED direction) is passed through in the figure. The result obtained by passing the polarizing plate 70 in the state of (g) of FIG. 16 to the output of (d) of FIG. 16 which is the two-dimensional optical signal 92 is (h) of FIG. 16 and only the contour component is obtained. Appears in the dark.

Although there are the above-described two types of contour extraction methods, in either case, the width of the contour component is the width of the polarization component in the MED direction and is equal over the entire input image 10 that is the input. .

The method of imaging the contour extraction result according to the third embodiment of the present invention is the same as that of the first embodiment of the present invention, and is performed as follows. The polarization state of the readout light 91 is the input image 1
It is modulated by the two-dimensional polarization modulation element 21 according to the light intensity distribution of 0. A part of the modulated two-dimensional optical signal 92 passes through the polarizing plate 70 set at an appropriate angle, and the desired contour image signal 93 is imaged as the output 30 by the image forming lens 60 which is an image forming means. . Either 70 or 60 may be installed first.

As described above, in the third embodiment of the present invention, it is assumed that the liquid crystal in the element is rotated by 45 degrees from the initial direction in the clockwise direction or the counterclockwise direction by the application of the control pulse. Polarization OFF in the same direction as the polarization direction of the readout light 91 and polarization O in the same direction as the polarization O
It has been described that N is output.

By the way, the liquid crystal of the two-dimensional polarization modulation element 21 is symmetrically θ from the initial direction in the clockwise or counterclockwise direction.
The polarization is turned off by an angle of 2 degrees (an angle that is not 90 degrees, for example, 80 degrees) relative to the two-dimensional polarization modulation element 21 that is rotated by an angle (an angle that is not 45 degrees, for example, 40 degrees). Even when an element that outputs polarization ON is used, the above description according to the third embodiment of the present invention is valid. In fact, when 2θ = 180 degrees, the contrast between the contour and the other portions becomes maximum.

Further, the liquid crystal of the two-dimensional polarization modulator 21 asymmetrically rotates from the initial direction to θ ₁ degree (eg 45 degrees) clockwise and θ ₂ degrees (eg 40 degrees) counterclockwise, Along with them, the two-dimensional polarization modulator 21
The above description is valid even when an element that outputs polarized light OFF and polarized light ON which forms an angle of relative (θ ₁ + θ ₂ ) degrees (for example, 85 degrees) is used.

Further, the angle θ at which the liquid crystal rotates clockwise or counterclockwise from the initial direction (for example, 22.5 degrees).
With that, the relative angle between the output of polarization OFF and the output of polarization ON does not become 2θ degrees (for example, 90 °).
The above description is applicable to the case of using the (degree) element.

[0180]

As described above, an input image including all spatial frequencies, that is, an object illuminated by natural light
Since a two-dimensional image can be directly processed as an input target, a two-dimensional contour image of an object moving at high speed can be extracted. It is possible to realize a very simple and high-speed contour extracting device that can be configured with an optical device such as liquid crystal that consumes little energy or an optical component that causes little loss of optical signals at low cost. Functions such as noise removal and edge enhancement can be realized by means of adjusting the light intensity and focus of the input image. Since these means can be easily controlled like a camera lens, the contour can be extracted while confirming the result in real time. Furthermore, the contour extraction device of the present invention can be connected in parallel to extract the boundary of color information as a contour.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a system configuration diagram of a first embodiment of the present invention.

FIG. 3 is a diagram showing a structure of a two-dimensional polarization modulation element.

FIG. 4 is a diagram showing control pulses of a two-dimensional polarization modulator according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of an operation principle of the two-dimensional polarization modulation element.

FIG. 6 is a diagram illustrating contour extraction processing according to the first embodiment of this invention.

FIG. 7 is a diagram showing a contour extraction processing result according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating a contour extraction process in which a correct contour cannot be obtained.

FIG. 9 is a diagram showing the polarization angle of read light and M
It is a figure explaining the outline extraction process which matched the ED direction.

FIG. 10 is a graph showing the output light intensity of a two-dimensional polarization modulator with a symmetric rotation angle.

FIG. 11 is a graph showing the output light intensity of a two-dimensional polarization modulator with an asymmetric rotation angle.

FIG. 12 is a diagram showing a contour extraction processing result by light intensity adjustment according to an embodiment of the present invention.

FIG. 13 is a diagram showing a contour extraction processing result by focus adjustment according to an embodiment of the present invention.

FIG. 14 is a system configuration diagram of a second embodiment of the present invention.

FIG. 15 is a system configuration diagram of a third embodiment of the present invention.

FIG. 16 is a diagram illustrating contour extraction processing according to the third embodiment of this invention.

[Explanation of symbols]

 10 Input image 20 Reflective two-dimensional polarization modulator 21 Transmissive two-dimensional polarization modulator 30 Output result 40,70 Polarizer 50,60 Lens 51 Aperture 80 Semi-transparent mirror 81 Polarization beam splitter 90 Light source 91 Linearly polarized light Read light 92 Modulated 2D optical signal 93 Contour component 2D optical signal 100 Control unit 200 Image input means 210 Polarization modulation means 220 Image reading means 230 Polarized image output means

Claims (9)

[Claims] 1. A polarization modulator that receives read light and write light and changes the polarization angle of the read light according to the light intensity of the write light; and write the light of an input image to the polarization modulator. A means for supplying light as a light, an image reading means for supplying light polarized in one direction as the reading light to the polarization modulating means, and a light polarized at a predetermined angle out of the output light of the polarization modulating means And a polarization image output means for outputting the contour of an image, wherein the relative angle between the polarization direction of the characteristic of the polarization modulation means and the polarization angle of the readout light is set to a predetermined angle. apparatus. 2. A first polarization corresponding to the two types of intensities read out from the polarization modulation unit to which light of predetermined two types of light intensity is input as the polarization direction on the characteristic of the polarization modulation unit. The image contour extracting device according to claim 1, wherein the angle is an intermediate angle between the angle and the second polarization angle. 3. The first polarization angle depends on the intensity of light at which the polarization angle of the polarization modulation means reaches a value in a saturated state, and the second polarization angle is the light whose input to the polarization modulation means is blocked. 3. The image contour extraction device according to claim 2, wherein the contour extraction device responds to the intensity of the image. 4. The bisector direction of the angle formed by the first polarization angle and the second polarization angle coincides with the direction of the polarization angle of the readout light. Image contour extraction device. 5. The bisector direction of the angle formed by the first polarization angle and the second polarization angle forms an angle of 45 degrees with the polarization direction of the readout light. Item 3. The image contour extraction device according to item 3. 6. The image input means comprises means for adjusting the light intensity of the input image.
An image contour extraction device described. 7. The image contour extracting apparatus according to claim 1, wherein the image input unit has a unit for adjusting a depth of focus of the input image. 8. The image contour extracting apparatus according to claim 1, wherein the image input unit has a unit for adjusting a focus of the input image. 9. The image contour extracting apparatus according to claim 1, further comprising means for controlling timings of the writing light and the reading light and controlling irradiation of the reading light.