JPH04128604A - Edge extracting apparatus - Google Patents

Abstract

PURPOSE:To extract edges of high space frequency surely by carrying out relative displacement of an objective image and eye-cell element array by a displacement means by moving an image forming optical system toward rectangular direction to an optical axis. CONSTITUTION:The facing distance of a diffusion plane 2A of a diffusion plane part 2 and eye-cell element arraying plane 9 is made to be adjustable by moving the diffusion plane part 2 rightward and leftward in the figure by a distance adjusting means 15. An image forming optical system 13 forms the image of an object 12 as an object image on the diffusion plane 2A. When the space frequency of the edges to be extracted is high (at this time the distance adjusting means 15 sets the distance of the diffusion plane 2A and the eye-cell element array plane to be sufficiently narrow), a displacement means 16 moves the image-forming optical system 13 swingingly upward and downward in the figure and in the direction rectangular to the figure plane with a pitch of the eye-cell element array. Consequently, edges of the object image can be extracted as an array set of the eye-cell element which send swinging outputs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an edge extraction device. This device can be used as an artificial vision device.

F. Prior Art] As a method for extracting edges of a target image, ``an image of the target object is formed on a diffusion surface, and individual photoreceptor cells of a photoreceptor cell element array arranged close to and facing the diffusion surface are used. A J method has been proposed in which edge extraction is performed depending on the presence or absence of output from an element.

Since the present invention relates to such an edge extraction method, the edge extraction method will be briefly explained below.

Referring to FIG. 2(a), reference numeral 2 indicates a diffusion surface member. The diffusion surface member 2 has a thin plate shape, and the surface facing downward in the figure is a diffusion surface 2A. Specifically, ground glass, for example, can be used as the diffusion surface member.

In FIG. 2(a), reference numeral 3 indicates a center light receiving element, and reference numeral 4 indicates a peripheral light receiving element. In the example shown in this figure, the center light receiving element 3 has a circular shape, and the peripheral light receiving elements 4 have an annular shape and are arranged concentrically with the center light receiving element 3. The center light-receiving element 3 and the peripheral light-receiving element 4 form a pair to constitute a photoreceptor element.

Note that the photoreceptor cell element is composed of, for example, nine square light-receiving elements arranged closely in 3 rows and 3 columns, with one in the center serving as the center light-receiving element;
Various configurations are possible, such as using the eight surrounding light receiving elements as peripheral light receiving elements.

The output of the central light receiving element 3 is amplified by an amplifier 5, and the output of the peripheral light receiving element 4 is amplified by an amplifier 6.

The outputs of the amplifiers 5 and 6 are subjected to differential calculation by a calculator 7.

The amplifiers 5 and 6 and the arithmetic unit 7 constitute what can be called an optic nerve element connected to a photoreceptor element constituted by the central light receiving element 3 and the peripheral light receiving elements 4.

In this way, a photoreceptor cell element and an optic nerve element connected to the photoreceptor cell element are taken as one unit, and the photoreceptor cell elements arranged closely two-dimensionally are called a photoreceptor cell element array. Figure 2 (a
), reference numeral 9 indicates the photoreceptor element arrangement surface of the photoreceptor cell element array. The diffusion surface member 2 is arranged with its diffusion surface 2A closely facing the photoreceptor element arrangement surface 9.

Now, consider a state in which the diffusion surface 2A of the diffusion surface member 2 is illuminated with uniform illuminance everywhere. The amplification factor of the amplifier 5.6 is adjusted so that the output of the arithmetic unit 7 becomes 0 in this state.

An image of an object (not shown) is formed as an object image on the diffusing surface 2A by an imaging optical system (not shown). Then, each part of the diffusion surface 2A diffuses light according to the light intensity of the target image toward the photoreceptor element arrangement surface 9. When the central light-receiving element and the peripheral light-receiving collector that make up each photoreceptor cell element receive diffused light from the diffusing surface, they output a signal according to the amount of received light, but the output from the arithmetic unit connected to the photoreceptor cell element is This is only the case when the intensity of the diffused light received by the photoreceptor cell element changes within the photoreceptor cell element. When viewed dimensionally, the outline of the target image, that is, the edge of the target image can be detected.

In order to see the characteristics of the output from the arithmetic unit in the photoreceptor cell element array, light is formed into a minute spot and imaged on the diffusing surface, and this spot is focused on a straight line passing through the center of the photoreceptor cell element (taken as the X direction). ), the X coordinate of the spot and the outputs α and β of the center and peripheral photoreceptor elements of the photoreceptor cell element become as shown in FIG. 2(b). To be precise, α and β are values amplified by an amplifier, and since the output of the arithmetic unit is the difference between α and β, β is shown with a negative weight. Therefore, in FIG. 2(b), α+β becomes the output of the arithmetic unit.

The behavior of α, β, α and β is the distance between the photoreceptor element array surface 9 and the diffusion surface 2A. It depends. That is, Fig. 2 (c
) spacing as shown. becomes larger, α and α+
The mountain shape of β becomes gentler. Conversely, it will be easily understood that the smaller the distance Do becomes, the steeper the mountain shapes of α and α+β become.

Generally, a target image formed on a diffusion surface includes various spatial frequencies. In this case, Fig. 2 (bXc
), in order to extract edges with higher spatial frequencies, the distance between the photoreceptor element array surface and the diffusion surface must be adjusted. It is intuitively understood that the value should be smaller.

In fact, the edge extraction sensitivity to the spatial frequency of edges in the target image is approximately the same as the interval. The extraction sensitivity of edges with low spatial frequencies becomes relatively high as Do increases. Figure 3 shows this situation. Let R be the diameter of one photoreceptor element, and use the above spacing. , (1/4)R
, (3/4)R, (5/4)R, and 2R, the value of the spatial frequency at which the sensitivity is maximum is shown in Figure 3 (a).
), (b), and (cXd).

[Problems to be Solved by the Invention] The problem to be solved by the present invention is when the spatial frequency of edges to be extracted is high in the edge extraction method as described above. If the spatial frequency of the edges to be extracted is high, use the interval as described above.

It would be better to make it smaller, but like this. When is made extremely small, a state is created in which a change in light intensity corresponding to an edge on the photoreceptor element array surface occurs only within one photoreceptor cell.

Referring to FIG. 4, the symbol Si −1+ Si +
S i + 1 indicates photoreceptor elements adjacent to each other.

As shown in the figure, there is a sharp edge EG with an extremely high spatial frequency in the photoreceptor element S1, and if we consider that the left side of the edge EG has a uniform light intensity and the right side is a dark area, the photoreceptor element 51-1 is Since it receives uniform light irradiation, it does not output any output, and since the photoreceptor cell element S,+ does not receive light, it does not output a-power.

In addition, in the photoreceptor element S, the edge part divides the element into two, so the output α of the center photoreceptor and the output β of the peripheral photoreceptor
cancel each other out, resulting in an output of 0 or a value close to 0. Since the output of the arithmetic unit is subjected to threshold processing to remove noise, an output close to O in such a case is expressed as O.

Therefore, in the case of FIG. 4, the edge EG is not extracted even though the edge EG actually exists at the position of the photoreceptor element S1.

A photoreceptor element that does not extract an edge even though it is located at the edge EG is referred to as a "missing eye" in the photoreceptor element array.

An object of the present invention is to provide a novel edge extraction device that can reliably extract high spatial frequency edges without causing such "blind spots."

[Means for Solving the Problems] The edge extraction device of the present invention is a device for extracting edges of a target image, and includes a photoreceptor element array, a diffusion surface member, an imaging optical system, an interval adjustment device, and a displacement device. and has.

The "photoreceptor cell element array" consists of a "photoreceptor cell element" consisting of a central photoreceptor and peripheral photoreceptors installed surrounding it, and the outputs of the center and peripheral photoreceptors are amplified to a predetermined amplification ratio. One unit consists of a pair of amplifiers, and an arithmetic unit that calculates and outputs the amplified output difference between the central light receiving element and the peripheral light receiving elements based on the respective outputs of these amplifiers. It will be arranged.

As the photoreceptor elements, amplifier pairs, and arithmetic units, those described with reference to FIG. 2 can be used. One of the two amplifiers constituting the amplifier pair may be a polarity inverting amplifier whose output has the opposite polarity to the output of the other, and the arithmetic unit may be a simple adder.

The "diffusion surface member" is disposed with its diffusion surface closely facing the photoreceptor cell element arrangement surface of the photoreceptor cell element array.

The "imaging optical system" forms an image of the object as a target image on the diffusing surface of the diffusing surface member.

The "interval adjustment means" changes the interval between the diffusion surface of the diffusion surface member and the photoreceptor element arrangement surface of the photoreceptor array. By adjusting the "distance between the diffusion surface of the diffusion surface member and the photoreceptor element array surface of the photoreceptor array" by this distance adjustment means, it is possible to selectively extract an edge having a desired spatial frequency in the target image.

The "displacement means" moves the target image and the photoreceptor cell element array at right angles by an arrangement pitch of the photoreceptor cell elements within the photoreceptor cell element array plane.
relatively displaced in the direction.

The displacement means ('displacement between the target image and the photoreceptor element array in which photoreceptor element array plane') may be performed in a vibrational manner (claim 2).

Further, "relative displacement between the target image and the photoreceptor element array by the displacement means" may be performed by "displacing the imaging optical system in a direction perpendicular to the optical axis" (Claim 3). , may be carried out by "displacing the photoreceptor cell element array in the direction of the photoreceptor cell element array surface" (claim 4);
The imaging optical system and the photoreceptor cell element array may be integrated and displaced in a direction perpendicular to the optical axis of the imaging optical system (claim 5).

[Function] Returning to FIG. 4, if the edge EG is displaced, for example, to the right by the arrangement pitch of the photoreceptor elements, the photoreceptor elements S,
The pressure in S2.1 changes. Therefore, an edge exists at the photoreceptor element position where the output changes due to the relative displacement between the target image and the photoreceptor element array. Therefore, if the above displacement is performed in two orthogonal directions, even edges with high spatial frequencies as shown in FIG. 4 can be reliably extracted.

At this time, the displacement may be only one degree, but if the displacement is performed oscillatingly, that is, if the edge position is determined using the diameter of the photoreceptor element S1 as an amplitude in FIG. Vibratory pressure can be extracted continuously over time, which is convenient for subsequent information processing. In this case, the relative displacement is performed at a sufficiently high frequency so that the output vibration occurs in a sufficiently short time compared to the subsequent information processing time.

Example] Three specific examples are listed below.

FIG. 1(a) shows an embodiment of the apparatus according to claim 3.

The reference numeral 2 is the same diffusion surface member as in FIG. 2, and the reference numeral 8 does not indicate the photoreceptor element array. Reference numeral 9 indicates a photoreceptor element array surface.

Further, reference numeral 11 indicates a combination of a photoreceptor element, an amplifier pair, and an arithmetic unit constituting one unit of the photoreceptor element array. These are similar to those described with reference to FIG.

The distance between the diffusing surface 2A and the photoreceptor cell element array surface 9 of the diffusing surface member 2 can be adjusted by moving the diffusing surface member 2 in the left-right direction in the figure using the distance adjusting means 15.

An imaging optical system indicated by reference numeral 13 forms an image of the object 12 on the diffusing surface 2A as a target image.

Reference numeral 16 indicates displacement means. The displacement means 16 moves the imaging optical system unit 3 when the spatial frequency of the edge to be extracted is high (at this time, the interval adjustment means 15 sets the interval between the diffusion surface 2A and the photoreceptor element array surface to be sufficiently small). The arrangement pitch of the photoreceptor elements is vibrably displaced in the vertical direction of the figure and in the direction orthogonal to the figure, with the arrangement pitch of the photoreceptor elements as the amplitude. As a result, the edges of the target image can be extracted as a set of arrays of photoreceptor elements that produce vibratory output.

FIG. 1(b) shows an embodiment of the apparatus according to claim 4.

To avoid complication, the same reference numerals as in FIG. 1(a) are used for items that are considered to have no risk of confusion.

In the embodiment shown in FIG. 1(b), reference numeral 17 indicates a displacement means.

When the spatial frequency of the edge to be extracted is high, the displacement means 17 vibrably displaces the photoreceptor cell element array 8 in the vertical direction of the drawing and in the direction orthogonal to the drawing, using the arrangement pitch of the photoreceptor cell elements as an amplitude. As a result, the edges of the target image can be extracted as a set of arrays of photoreceptor elements that produce vibratory output.

FIG. 1(c) shows an embodiment of the apparatus according to claim 5.

In this figure as well, the same reference numerals as in FIG. 1(a) are used for parts that are considered to be free from confusion.

In the embodiment shown in FIG. 3(c), the reference numeral 18 indicates a force (displacement means).The displacement means 18 is used to integrate the imaging optical system 13 and the photoreceptor element array 8 when the spatial frequency of the edge to be extracted is high. As a result, the array pitch of the photoreceptor elements is vibrated in the vertical direction of the diagram and in the direction orthogonal to the diagram as an amplitude.This allows the edges of the target image to be extracted as the array connection of the photoreceptor elements that produce a vibratory output. .

[Effects of the Invention] As described above, according to the present invention, a novel edge extraction device can be provided. Since this device has the above-described configuration, it is possible to extract the edges of the target image without causing the "knock-outs" that have been a problem with conventional edge extraction devices.

In carrying out the present invention, when the target image and the photoreceptor element array are relatively displaced in two orthogonal directions by the arrangement pitch of the photoreceptor elements within the photoreceptor element array plane, it is assumed that the displacement is only once. Irrespective of whether it is vibrational or not, the "array pitch" does not have to be a displacement strictly equal to the array pitch, and it is sufficient that the displacement is substantially equal to the array pitch. In other words, the arrangement pitch means "approximately the arrangement pitch."

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention in detail, FIGS. 2 and 3 are diagrams for explaining the prior art, and FIG. 4 is a diagram for explaining the present invention in detail. 200. Diffusion surface member, 800. Photoreceptor cell element array, 12
．． ,. Object, 13. ,,Imaging optical system, 16.17.18.
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Claims (1)

[Scope of Claims] 1. A device for extracting edges of a target image, which comprises a photoreceptor element composed of a center light receiving element and peripheral light receiving elements surrounding the central light receiving element, and the center and peripheral light receiving elements. One unit consists of a pair of amplifiers that amplify the output of the element to a predetermined amplification ratio, and an arithmetic unit that calculates and outputs the amplified output difference between the center light receiving element and the peripheral light receiving elements based on the respective outputs of these amplifiers. a photoreceptor cell element array formed by closely arranging cell elements in a two-dimensional manner; a diffusion surface member disposed with a diffusion surface closely facing the photoreceptor cell array surface of the photoreceptor cell element array; an imaging optical system that forms an image on the diffusing surface of the diffusing surface member as a target image; and an interval adjustment means that changes the distance between the diffusing surface of the diffusing surface member and the photoreceptor element arrangement surface of the photoreceptor array. and a displacement means for relatively displacing the target image and the photoreceptor cell element array in two orthogonal directions by the photoreceptor element array pitch within the photoreceptor cell element array plane. 2. The edge extraction device according to claim 1, wherein the relative displacement between the target image and the photoreceptor element array by the displacement means is performed in a vibrational manner. 3. According to claim 1 or 2, the relative displacement between the target image and the photoreceptor element array by the displacement means is performed by displacing the imaging optical system in a direction perpendicular to the optical axis. edge extraction device. 4. Claim 1 or 2, characterized in that the relative displacement between the target image and the photoreceptor element array by the displacement means is performed by displacing the photoreceptor element array in the direction of the photoreceptor element array plane. edge extraction device. 5. In claim 1 or 2, the relative displacement between the target image and the photoreceptor element array by the displacement means causes the imaging optical system and the photoreceptor element array to be integrated into an optical axis of the imaging optical system. An edge extraction device characterized in that the edge extraction is performed by displacement in orthogonal directions.