JP2863290B2 - Edge extraction device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an edge extracting device. This device can be used for an artificial vision device.

[Related Art] As a method of extracting an edge of a target image, an image of an object is formed as a target image on a diffusion surface, and individual photoreceptors of a photoreceptor cell array arranged in close proximity to the diffusion surface are arranged. Edge extraction based on the presence / absence of an output from an element "has been proposed.

Since the present invention relates to such an edge extraction method, the following briefly describes the edge extraction method.

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

In FIG. 2A, reference numeral 3 is a central light receiving element, and reference numeral 4 is
Indicates a peripheral light receiving element. The center light receiving element 3 has a circular shape in the example of this figure, and the peripheral light receiving element 4 has an annular shape and is arranged so as to form a concentric circle with the center light receiving element 3. The center light receiving element 3 and the peripheral light receiving element 4 form a pair to form a photoreceptor cell element.

The photoreceptor elements are, for example, nine square light receiving elements arranged closely in three rows and three columns, with one at the center serving as a central light receiving element and eight surrounding light receiving elements serving as peripheral light receiving elements. Various configurations are possible.

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

The outputs of the amplifiers 5 and 6 are subjected to a difference calculation by a calculator 7.
The amplifiers 5 and 6 and the arithmetic unit 7 constitute what should be called an optic nerve element connected to the photoreceptor cell constituted by the central light receiving element 3 and the peripheral light receiving element 4.

The visual cell element and the optic nerve element connected to the visual cell element as one unit, and the visual cell elements arranged two-dimensionally in close contact are referred to as a visual cell element array. In FIG. 2A, reference numeral 9 denotes a photoreceptor cell array surface of the photoreceptor cell array. The diffusion surface member 2 is provided with its diffusion surface 2A closely facing the photoreceptor cell array 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 factors of the amplifiers 5 and 6 are 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 diffusion surface 2A by an imaging optical system (not shown). Then, each part of the diffusion surface 2A diffuses light corresponding to the light intensity of the target image toward the photoreceptor cell array surface 9. When the central light receiving element and the peripheral light receiving element constituting each photoreceptor cell receive the diffused light from the diffusing surface, they output a signal corresponding to the amount of received light. This is only when the intensity of the diffused light received by the photoreceptor cell changes within the photoreceptor cell. Therefore, a set of photoreceptor elements according to the computing unit that outputs the light in the photoreceptor cell array is two-dimensional. In other words, the outline of the target image, that is, the edge of the target image can be detected.

In order to observe the characteristics of the output from the computing unit in the photoreceptor cell array, light is imaged as a minute spot on the diffusion surface, and this spot is formed as a straight line (X
Moving along the direction), the X of the spot
The coordinates and the outputs α and β of the photoreceptor elements at the center and the periphery of the photoreceptor cell are as shown in FIG. 2 (b). To be precise, α and β are values amplified by the amplifier, and β is given a negative weight since the output of the arithmetic unit becomes the difference between α and β. Therefore, in FIG. 2B, α + β is the output of the arithmetic unit.

alpha, beta, behavior of alpha + beta is different by the distance D ₀ between the visual cell element array surface 9 diffusing surface 2A. That is, FIG. 2 (c)
Yamagata distance D ₀ Gayori larger the alpha and alpha + beta as shown in becomes gentle. Conversely, it will be readily understood that the smaller the distance D _{0, the} steeper the peaks of α and α + β.

By the way, in general, a target image formed on a diffusion surface contains various spatial frequencies. In this case, FIG. 2 (b)
From what has been described with reference to (c), in order to extract the edge of the higher spatial frequencies, the distance D ₀ between the visual cell element array surface and the diffusion surface it is intuitively that should be smaller Will be understood.

In fact, the edge extraction sensitivity to spatial frequencies of the edge in the target image changes depending on the distance D _0, extraction sensitivity of the edge having a low spatial frequency with increasing D ₀ becomes relatively high. FIG. 3 illustrates this situation. 1 visual cells element pieces of diameter and R, the distance _{D 0, (1/4) R,} (3,4)
When sequentially increasing R, (5/4) R, and 2R, the values of the spatial frequency at which the sensitivity becomes maximum are as shown in FIGS. 3 (a), (b), (c), and (d).
It can be seen that they become smaller in the order of.

[Problem to be Solved by the Invention] The present invention has a problem when the spatial frequency of an edge to be extracted in the edge extraction method as described above is high. Although if the spatial frequency of the to be extracted edges is high may be reduced spacing D ₀ As described above, when the thus was very small D ₀ is on the visual cell element array surface, corresponding to the edge This results in a state in which the change in light intensity occurs only in one photoreceptor cell.

Referring to FIG. 4, reference numerals S _i-1 , S _i , and S _{i + 1} indicate photoreceptor elements adjacent to each other.

Sharp in a portion of the photoreceptor cell element S _i as shown in the figure, i.e., there is a very high edge EG of the spatial frequency, the left uniform light intensity of the edge EG, a photoreceptor cell element right consider as dark portion S _{i- 1} does not produce output because it receives uniform light irradiation,
Since the photoreceptor cell element _{Si + 1} does not receive light, it does not output any light.

In the photoreceptor cell element _Si , the edge portion bisects the element, so that the output α of the central light receiving element and the output β of the peripheral light receiving element
Cancel each other, and the output becomes 0 or a value close to 0. Since the output of the arithmetic unit is subjected to threshold processing for noise removal, an output close to 0 in such a case is represented as 0.
For this reason FIG. 4, in fact despite the edge EG is present at the position of the visual cells element S _i is the edge EG is not extracted.

A photoreceptor element that does not extract an edge in spite of being located at the position of the edge EG in this manner is referred to as a “crosstalk” in the photoreceptor element array.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel edge extracting device capable of reliably extracting an edge having a high spatial frequency without generating such a “strigger”.

[Means for Solving the Problems] The edge extracting apparatus of the present invention is an "apparatus for extracting edges of a target image", and includes a photoreceptor cell array, a diffusing surface member, an imaging optical system, an interval adjusting means, and a displacement means. And

The “photoreceptor cell array” is composed of a central photoreceptor, a “photoreceptor cell” provided to surround the central photoreceptor, and an output of the central / peripheral photoreceptor to a predetermined amplification ratio. A pair of amplifiers and an arithmetic unit for calculating and outputting an amplified output difference between the central light receiving element and the peripheral light receiving element based on the output of each of these amplifiers are defined as one unit, and the photoreceptor elements are closely arranged two-dimensionally. Do it.

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

The “diffusion surface member” is disposed with the diffusion surface closely opposed to the photoreceptor cell array surface of the photoreceptor cell array.

The “imaging optical system” forms an image of the target object as a target image on the diffusion surface of the diffusion surface member.

The “interval adjusting means” changes an interval between the diffusion surface of the diffusion surface member and the photoreceptor cell array surface of the photoreceptor cell array. By adjusting the “distance between the diffusion surface of the diffusion surface member and the photoreceptor cell array surface of the photoreceptor cell array” by the interval adjustment means, an edge having a spatial frequency to be extracted in the target image can be selectively extracted.

The “displacer” relatively displaces the target image and the photoreceptor cell array in two orthogonal directions within the photoreceptor cell array plane by the arrangement pitch of the photoreceptor cell elements.

The "displacement between the target image and the photoreceptor cell array in the photoreceptor cell array plane" by the displacing means may be performed in an oscillatory manner (claim 2).

The "relative displacement between the target image and the photoreceptor cell array by the displacement means" may be performed by "displacing the imaging optical system in a direction perpendicular to the optical axis" (claim 3). This may be performed by "displacing the photoreceptor cell array in the direction of the photoreceptor cell array plane" (claim 4),
This may be performed by "displacing the imaging optical system and the photoreceptor cell array integrally in a direction orthogonal to the optical axis of the imaging optical system" (claim 5).

[Operation] Returning to FIG. 4, when the edge EG is displaced, for example, rightward by the arrangement pitch of the photoreceptor cell elements, the photoreceptor cell element S _i is displaced.
The output of S _{i + 1} changes. Therefore, an edge exists at the position of the photoreceptor element 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, it is possible to reliably extract even a high spatial frequency edge as shown in FIG.

At that time, although the displacement may be only once, when the displaced oscillatory, i.e. performs the cell diameter element S _i viewing the position of the edge as the amplitude in Figure 4, operations leading to the visual cell element S _i The vibratory output can be continuously taken out from the container in time, which is convenient for the 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 as compared with the subsequent information processing time.

[Examples] Hereinafter, three specific examples will be given.

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

Reference numeral 2 denotes a diffusion surface member as in FIG.
Indicates a photoreceptor cell array. Reference numeral 9 denotes a photoreceptor cell array surface.

Reference numeral 11 denotes a combination of a photoreceptor element, an amplifier pair, and a computing unit that constitute one unit of the photoreceptor cell array. These are the same as those described with reference to FIG.

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

The imaging optical system denoted by reference numeral 13 forms an image of the object 12 on the diffusion surface 2A as an object image.

Reference numeral 16 denotes a displacement means. When the spatial frequency of the edge to be extracted is high (at this time, the distance adjusting means
15 sets the distance between the diffusing surface 2A and the photoreceptor cell array surface to be sufficiently small), and causes the imaging optical system 13 to vibrate in the vertical direction of the drawing and the direction perpendicular to the drawing with the arrangement pitch of the photoreceptor device as the amplitude. To be displaced. As a result, the edge of the target image can be extracted as an array of photoreceptor elements that output an oscillating output.

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

In order to avoid complication, the same reference numerals as those in FIG. 1 (a) are used for those which do not seem to be confused.

In the embodiment shown in FIG. 1B, reference numeral 17 denotes a displacement means.
When the spatial frequency of the edge to be extracted is high, the displacement means 17 vibrates the photoreceptor cell array 8 in an up-down direction in the drawing and a direction perpendicular to the drawing, using the arrangement pitch of the photoreceptor cells as an amplitude. As a result, the edge of the target image can be extracted as an array of photoreceptor elements that output an oscillating output.

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

In this figure, the same reference numerals as those in FIG. 1 (a) are used for those which do not seem to be confused.

In the embodiment shown in FIG. 1C, reference numeral 18 denotes a displacement means.
When the spatial frequency of the edge to be extracted is high, the displacement unit 18 integrates the imaging optical system 13 and the photoreceptor cell array 8 and vertically orients the array pitch of the photoreceptor elements in a direction perpendicular to the drawing. Vibrationally displaces as amplitude. As a result, the edge of the target image can be extracted as an array of photoreceptor elements that output an oscillating output.

[Effects of the Invention] As described above, according to the present invention, a novel edge extraction device can be provided. Since this device is configured as described above, it is possible to extract the edge of the target image without causing "crossing" which is a problem in the conventional edge extracting device.

In the practice of the present invention, when the target image and the photoreceptor cell array are relatively displaced in the two orthogonal directions by the array pitch of the photoreceptor elements in the photoreceptor cell array plane, the displacement is 1
Regardless of whether the vibration is limited or not, the “arrangement pitch” does not need to be a displacement strictly equal to the arrangement pitch, and it is sufficient that the displacement is substantially equal to the arrangement pitch. That is, the arrangement pitch means “about the arrangement pitch”.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention, FIGS. 2 and 3 are diagrams for explaining a conventional technique, and FIG. 4 is a diagram for explaining a problem of the present invention. 2 ... diffusion surface member, 8 ... photoreceptor cell array, 12 ... object, 13 ... imaging optical system, 16, 17, 18 ... displacement means

Claims (5)

(57) [Claims] 1. An apparatus for extracting an edge of a target image, comprising: a photoreceptor element comprising a central light receiving element and a peripheral light receiving element surrounding the central light receiving element; A pair of amplifiers for amplifying the amplified output to a predetermined amplification ratio, and an arithmetic unit for calculating and outputting the amplified output difference between the central light receiving element and the peripheral light receiving element based on the output of each of these amplifiers.
A photoreceptor cell array in which the photoreceptor cell elements are closely arranged two-dimensionally as a unit, and a diffusion surface member provided with a diffusion surface close to and facing the photoreceptor cell array surface of the photoreceptor cell array. An imaging optical system that forms an image of a target object as a target image on the diffusion surface of the diffusion surface member, and sets an interval between the diffusion surface of the diffusion surface member and the photoreceptor cell array surface of the photoreceptor cell array. An interval adjusting means for changing, and displacing means for relatively displacing the target image and the photoreceptor cell array in two orthogonal directions within the photoreceptor cell array plane by the arrangement pitch of the photoreceptor cell elements. Edge extraction device. 2. The edge extracting apparatus according to claim 1, wherein the relative displacement between the target image and the photoreceptor cell array by the displacement means is performed in an oscillatory manner. 3. The relative displacement between the target image and the photoreceptor cell array by the displacement means according to claim 1 or 2, is performed by displacing the imaging optical system in a direction orthogonal to the optical axis. An edge extraction device, characterized in that: 4. The method according to claim 1, wherein the relative displacement between the target image and the photoreceptor cell array by the displacement means is performed by displacing the photoreceptor cell array in the direction of the photoreceptor cell array plane. An edge extraction device, characterized in that: 5. The imaging optical system according to claim 1, wherein relative displacement between the target image and the photoreceptor cell array by the displacement means is performed by integrating the imaging optical system and the photoreceptor cell array. An edge extracting device characterized by being displaced in a direction orthogonal to an optical axis.