JP2534285B2 - Image measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to arithmetic control means for sequentially designating addresses of an image memory storing image data, and image data sequentially outputted from the image memory according to the designation. The present invention relates to an image measuring device having a first accumulating means for accumulating.

(Prior Art) Conventionally, as shown in FIG. 4, an image measuring apparatus has a control circuit 53 for scanning an address of an image memory 51 storing image data based on a command from a microcomputer 52.
And an adder circuit 55 for adding the image data f _i output from the image memory 51 by this scanning and the signal value output from the first register 54. The first register 54 and the adder 55 Thus, the first accumulating means is configured, and the accumulated value Σf _i is calculated by this.

Further, the image measuring device includes a scanning counter 56 that counts the number of pixels corresponding to address scanning, and an image memory.
A multiplication circuit 57 for multiplying the image data f _i output from 51 by the count number i of the scanning counter 56 to obtain a multiplication value if _i.
And an addition circuit 58 for adding the multiplication value if _i of the multiplication circuit 57 and the output value of the second register 59, and Σif _i is output from the second register 59.

Now, when the control circuit 53 finishes scanning the address of the image memory 51, the microcomputer 52 calculates the image data from the accumulated value Σf _i of the first register 54 and the Σif _{i of} the second register at the end time according to the following equation. Center of gravity position of
Calculates g.

However, n is the number of pixels corresponding to the scanning start point to the end point of the address.

(Problems to be Solved by the Invention) Since the address scanning by the control circuit 53 is performed at high speed, it is necessary to perform the operation of the multiplication circuit 57 at high speed. To perform this multiplication at high speed, the multiplication circuit 57 is used. However, there was a problem that it became complicated and large-scale.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an image measuring apparatus capable of calculating the center of gravity of image data at high speed with a simple circuit configuration. .

(Means for Solving Problems) In order to solve the above problems, the present invention relates to arithmetic control means for sequentially designating addresses of an image memory storing image data, and sequentially designated from the image memory by the designation. In an image measuring device provided with a first accumulating means for accumulating output image data, a second accumulating means for accumulating accumulated values of the first accumulating means is provided, The arithmetic control means calculates the center of gravity of the image data from the accumulated values of the first and second accumulating means.

(Operation) The second accumulating means accumulates the accumulated values of the first accumulating means, and the arithmetic control means calculates the center of gravity of the image data from the accumulated values of the first and second accumulating means.

(Embodiment) An embodiment of an autorefractometer to which the image measuring device according to the present invention is applied will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing the arrangement of the optical system of the autorefractometer. In FIG. 1, 1 is a projection optical system for forming a ring-shaped image on the fundus Er of the eye E to be inspected,
2 is an imaging optical system for forming an image of the fundus Er on a CCD (image sensor) 3 as a two-dimensional image sensor, 4 is a fixation target optical system for fixing the eye E to be examined in a clouded state, 5
Is an observation optical system for observing the anterior segment Ea of the eye E to be examined.

The projection optical system 1 includes a perforated mirror 6, an infrared LED light source 7, a relay lens 8, a conical prism 9, a ring-shaped aperture stop 10, a relay lens 11, and an objective lens 21, and the imaging optical system 2 is an objective. A lens 21, a perforated mirror 6, a relay lens 13, and a CCD 3 are provided. The fixation target optical system 4 includes an objective lens 21,
Infrared transmission visible reflection mirror 14, relay lens 15, fixation target 16
The anterior eye observation optical system 5 includes an objective lens 21, a half mirror 20, a relay lens 17, an image pickup tube 18, and a monitor television.
19, ring-shaped aperture stop 10 and fundus Er, CCD3 and fundus E
r, the infrared light LED light source 7, the perforated mirror 6, and the eye Ep to be examined Ep are in a conjugate relationship. For example, the arrangement relationship between the optical systems 1 to 5 and the arrangement relationship between the respective constituent elements are disclosed in JP-A-60-164829. The detailed description is omitted here.

During the measurement, the image of the anterior segment Ea is always displayed on the screen of the monitor TV 19, the examiner appropriately monitors whether the anterior segment Ea is in a predetermined position, and the subject is The fixation target 16 is clouded and the eye E is fixed.

FIG. 2 is a block diagram showing the signal processing system of the autorefractometer. In the figure, 31 is a drive circuit for sequentially outputting the signal charges (image signals) accumulated in each pixel of the CCD 3, and 32 is an image sensor. An A / D converter for converting the image signal output from 3 into a digital signal, 33 is a target imaged on the CCD 3 by the imaging optical system 2 when the target image is projected on the fundus Er by the projection optical system 1. An image memory for storing image data of an image, in which digital signals sequentially output from the A / D converter 32 are sequentially stored at addresses corresponding to pixels of the CCD 3. 34 is an image memory 33 based on a command from a microcomputer 35 described later.
Control circuit for scanning the address of the image data and sequentially outputting the image data f _i stored at that address from the image memory 33, and 36 is the image data f _i output from the image memory 33 and the first register 37. In the first adder circuit for adding the signal value, the first adder circuit 36 and the first register 37 constitute a first accumulator, and the accumulated value S ₁ = Σfi from the first register 37 as in the conventional case. Is output.

Reference numeral 38 denotes a second adder circuit that adds the accumulated value S ₁ output from the first register 37 and the accumulated value output from the second register 39. The second adder circuit 38 and the second register 39 Accumulated value
The second accumulating means for accumulating S ₁ is configured, and the accumulated value S ₂ = Σ (N + 1−i) f _i is output from the second register 39.
The following table shows an example of the accumulated values S ₁ and S ₂ when N = 3.

Reference numeral 40 denotes a scan counter which counts the number N of pixels of the CCD 3 corresponding to the scan when the control circuit 34 scans the address of the image memory 33, which outputs N + 1 obtained by adding 1 to the count number. ing. Reference numeral 35 is a microcomputer that outputs a scan command signal to the control circuit 34 to scan the address of the image memory 33.
The centroid Ig of the image data is calculated from the accumulated values S ₁ and S ₂ output from the registers 37 and 39, the count number N + 1 output from the scanning counter 40, and the spherical refractivity of the eye E to be examined from the centroid Ig. , Astigmatism degree, astigmatic axis angle, etc. are calculated. Then, the microcomputer 35 and the control circuit 34
And constitute an arithmetic control unit.

 Next, how to find the center of gravity Ig will be described.

If the control circuit 34 scans the address of the image memory 33 at N points, the accumulated value S ₁ output from the first register 37 is S ₁
= Σf _i , the accumulated value S ₂ of the second register is Becomes From this equation, Therefore, the center of gravity position Ig is obtained as (Σif _i ) / Σf _{i, and} therefore S ₁ = Σf _i , so that Ig = {(N + 1) S ₁ −S ₂ } / S ₁ = N + 1−S ₂ / S ₁ ... Become. By the way, since N + 1 is the count number of the scanning counter 40 and S ₁ and S ₂ are the accumulated values of the first and second registers, the center of gravity position Ig can be calculated by the microcomputer 35 based on the equation. .

Next, the operation of the autorefractometer of the above embodiment will be described.

When infrared light is emitted from the LED light source 7 of the projection optical system 1, the infrared light is refracted by the conical prism 12 and then passes through the ring-shaped aperture stop 10 to be reflected by the perforated mirror 6 and the objective. Reach the fundus Er through the lens 21 and the fundus Er
A target image is formed on.

The target image formed on the fundus Er is a ring-shaped image (first ring image R), and the infrared light forming this primary ring image R ₁ is reflected by the fundus Er, and the holes of the perforated mirror 6 are reflected. Part 6a
And reaches the CCD 3, and a secondary ring image R ₂ as an image pattern is formed on the CCD 3. Then, the drive circuit 31
The CCD 3 sequentially outputs the signal charge (image signal) accumulated in each pixel, the image signal is converted into a digital signal by the A / D converter 32, and the digital signal is stored in the image memory 33 corresponding to each pixel. It will be remembered at the address.

Figure 3 is intended to illustrate the secondary ring image R _2, which are formed on the CCD 3, in FIG. 3, the secondary ring image R ₂ is formed in the hatched portion of the CCD 3. Where the first
The size of the secondary ring image R ₁ and the size of the secondary ring image R ₂ change in accordance with the refractive index of the eye E, and the shape of the eye E becomes elliptical when the eye E has astigmatism. Are known. Then, the degree of refraction and the like are obtained from this elliptical shape.

Here, in order to obtain the ellipse R ₃ , an arbitrary point O (X ₀ , Y ₀ )
Is the origin, and the scanning direction M is a direction that passes through the point O (X ₀ , Y ₀ ) and is at an angle θ with respect to the horizontal scanning direction H.
In the direction M, the measurement start point P ₁ and the measurement end point P ₂ are determined in advance.

Here, assuming that the obtained image pattern is an ellipse R ₃ indicated by a chain double-dashed line, a coordinate point for obtaining the coefficient of the elliptic equation based on the coordinate point defined as the intersection of the ellipse R ₃ and the scanning direction M. Must be at least 4 and therefore CCD3 is scanned in 4 or more directions.

Now, the image data f of the first ring image R ₂ is stored in the image memory 33.
Is stored, the control circuit 34 scans the address of the image memory 33 corresponding to the pixel in the M direction based on the instruction of the microcomputer 35, and the image data f _i is output from the image memory 33 by this scanning. It The image data f _i is accumulated by the first adder circuit 36 and the first register 37, and the accumulated value S ₁ = Σf _i is output from the first register 37. Then, the accumulated value S ₁ is accumulated by the second adder circuit 38 and the second register 39, and the accumulated value S ₂ = Σ (N + 1-i) f _i is output from the second register 39. . on the other hand,
From the scanning counter 40, the count number N + which is obtained by adding 1 to the pixel number N of the CCD 3 corresponding to the scanning of the address of the image memory 33
1 is output, and the microcomputer 35 outputs S ₁ , S
Based on the formula from ₂ , N + 1, the barycentric position Ig of the image data f _i is calculated.
Is calculated. This center of gravity position Ig is determined by the scanning direction M (P ₁ -P
_The position of the center of gravity of the image data in (between ₂ ) is the intersection of the ring R ₃ and the scanning direction M.

In the same manner, three different points of intersection are obtained.
From these intersections, the microcomputer 35 obtains the coefficients A, B, C by the following formula.

Ax ² + By ₂ + Cxy = 1 ... That is, in FIG. 2, assuming that the horizontal scanning direction is the X axis, the major axis of the ellipse R ₃ is a, the minor axis is b, and the X of the major axis a.
Assuming an angle φ with respect to the axis, the angle φ corresponds to the astigmatic axis, the major axis a corresponds to the refraction of the strong main meridian of astigmatism, and the size of the ellipse corresponds to the spherical power. , B, C, the refractive powers S, C, A can be obtained.

That is, if at least four or more coordinate points are detected and their coordinate values are obtained, A, B and C are obtained from the equations by the method of least squares, and if a, b and φ are obtained from the equations, the refractive index can be obtained.

Thus, it obtains the accumulated value S ₂ from the accumulated value S _1, and these accumulated value S _1, S _2, since the so computes the centroid position from the count number N + 1 Metropolitan of the second register 39, a conventional Therefore, it is not necessary to provide a multiplication circuit as described above, and therefore the spherical refractive index, the astigmatic degree, the astigmatic axis angle, etc. can be calculated at high speed with a simple circuit configuration.

(Effects of the Invention) The present invention is a first control unit for sequentially designating addresses of an image memory storing image data, and image data sequentially output from the image memory according to the designation. In an image measuring device provided with a calculating means, a second accumulating means for accumulating the accumulated value of the first accumulating means is provided, and the arithmetic control means is a first and a second accumulating means. Since the center of gravity of image data is calculated from the accumulated value, the center of gravity of image data can be calculated at high speed with a simple circuit configuration.

[Brief description of drawings]

Fig. 1 is a conceptual diagram showing the arrangement of the optical system of the autorefractometer, Fig. 2 is a block diagram showing the signal processing system of the autorefractometer, and Fig. 3 is a ring image formed on the CCD. FIG. 4 is a block diagram showing the configuration of a conventional image measuring device. 33 ... Image memory, 34 ... Control circuit 35 ... Microcomputer, 36 ... First addition circuit 37 ... First register, 38 ... Second addition circuit 39 ... Second register

Claims (2)

(57) [Claims] 1. An arithmetic control means for sequentially designating addresses of an image memory storing image data, and a first accumulating means for accumulating image data sequentially outputted from the image memory by the designation. In the image measuring device provided, a second accumulating means for accumulating the accumulated value of the first accumulating means is provided, and the arithmetic control means calculates from the accumulated values of the first and second accumulating means. An image measuring device, characterized in that the center of gravity of image data is calculated. 2. When the accumulated value of the first accumulating means is S1, the accumulated value of the second accumulating means is S2, and the address value N of the image memory is N, the arithmetic control means, The center of gravity Ig of the image data is (N +
1) image measuring apparatus claims paragraph 1, wherein the determination by calculation of -S ₂ / S _1.