JPH07119922B2 - Depth of focus correction device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a depth-of-focus correction device that corrects a depth of focus determined by an optical system.

[Prior art]

Conventionally, the depth of focus in an image pickup device such as an electronic camera is determined as follows. That ’s As described above, since it is determined by the constants peculiar to the optical system such as the lens, there is a problem that the optical system must be changed to correct the depth of focus.

〔Purpose〕

The present invention has been made in view of the above problems, and an object thereof is to provide a depth-of-focus correction device capable of correcting the depth of focus without changing the optical system.

[Means and actions for solving the problems]

In the present invention, in order to achieve the above object, the depth-of-focus correction device is configured as in (1) below.

(1) Image separating means for spatially dividing light so as to separate an optical image from a subject incident through an optical system into a plurality of planes having different focal positions, and each of the image forming means formed by the image separating means. Discrimination for comparing the spatial frequency in the same portion of the optical image respectively imaged on each plane by the plurality of image capturing means for capturing an image and discriminating the signal portion from the image capturing means having the maximum spatial frequency A depth-of-focus correction device comprising: a hand; a selection unit that selectively extracts an image signal of a signal portion having the maximum spatial frequency; and a combination unit that combines the image signals selected by the selection unit.

With the configuration (1), a single image focused on any part of the screen can be obtained without changing the optical system. Further, even when a moving subject is imaged, it is possible to prevent the images from being misaligned when the images are combined and to fail to combine the images.

[Example showing principle]

 An embodiment of the present invention will be described below with reference to FIG.

In the figure, 1 is a three-dimensional object, 2 is an image sensor such as a CCD that captures an optical image from the object 1 through an optical system 3, and 4 is an image sensor 2 that moves the image sensor 2 in the optical axis direction. The servo mechanism located on the planes I, II, and III constitutes the image pickup means A together with the image pickup element 2. Reference numeral 6 denotes an A / D converter that converts the image signal output from the image pickup means A through the amplifier 5 into a digital signal, and 7 performs a predetermined signal processing on the image signal from the A / D converter 6 to increase the screen size. A signal processing circuit MI, MII, MIII for adjusting the position and the position, etc., stores the image signal output from the signal processing circuit 7.
In one frame memory, the image signal for one frame obtained by capturing the image on the plane I is stored in the frame memory MI, and the image signal for one frame obtained by capturing the image on the plane II is transmitted to the frame memory MII.
In addition, the image signals for one frame obtained by imaging on the plane III are stored in the frame memory MIII. Note that pixel signals obtained from the same pixel of the image pickup device 2 located on each plane are stored at the same address of each memory MI, MII, MIII. 8a, 8b, 8c are the above 3
3 differentiators connected to 3 memories MI, MII, MIII,
Of these, the difference unit 8a is connected to the frame memory MI, the difference unit 8b is connected to the frame memory MII, and the difference unit 8c is connected to the frame memory MIII. Reference numeral 9 is a comparator which constitutes the discriminating means B together with the differentiators 8a, 8b and 8c, and compares the outputs from the respective differentiators 8a, 8b and 8b to discriminate which one has the maximum value. And has the following configuration. That is, 9a ₁ is a comparator that compares the outputs a and b of the differencers 8a and 8b, 9a ₂ is a comparator that compares the outputs b and c of the differencers 8b and 8c, and 9a ₃ is the output a of the differencers 8a and 8c. Comparing c, each comparator 9a ₁ ,
From 9a ₂ and 9a ₃ , "1" is output when the non-inverting input is large. 9b _{1 and} comparator 9b ₁
9b ₂ is a gate circuit to which the signal from 9b ₂ is input, 9b ₂ is a gate circuit to which the signals from comparators 9a ₂ and 9a ₃ are input, and 9b ₃
Is a gate circuit to which the signals from the comparators 9a ₁ and 9a ₃ are input, and these three gate circuits 9b ₁ , 9b ₂ and 9b ₃ output signals from the comparators 9a ₁ , 9a ₂ and 9a _{3 in the} preceding stage. On the other hand, the signals as shown in Table 1 are output.

Also, 10a, 10b, 10c are the three frame memories MI, MI, M
3 connected between III and frame memory 11 for image composition
The number of switches constitutes a selection circuit C as a selection means, and the signals from the AND circuits 9b ₁ , 9b ₂ and 9b ₃ are used to output O.
N, OFF is controlled. 12 is a CPU that controls the above circuits, 13
Is a keyboard for inputting to the CPU 12.

Next, the operation will be described based on the flowchart of FIG.

First, in response to a control signal from the CPU 12, the servo mechanism 4 positions the image pickup element 2 on the image pickup plane I (step 1), and picks up an optical image from the subject 1 incident through the optical system 3 ( Step 2). The image signal obtained from the image pickup device 2 is stored in the frame memory MI after passing through the amplifier 5, the A / D converter 6 and the signal processing circuit 7 (step 2). After that, the servo mechanism 4 moves the image pickup device 2 to the image pickup planes II and III, and the image signals obtained by picking up images on the respective planes are stored in the frame memories MII and MIII as in the above (steps 3 to 6). The image obtained by picking up on each plane is stored in each frame memory MI, MII, MIII with the size and position of the screen adjusted by the signal processing circuit 7.
Then, after an address signal is given to the frame memories MI, MII, MIII and the image synthesizing memory 11 (step 7), the pixel signals of the same address are read out from the respective frame memories MI, MII, MIII and the image synthesizing memory 11 is read. To write mode (step 8). Frame memory MI, M
The pixel signals read from II and MIII are input to the difference units 8a, 8b and 8c. Each of the difference units 8a, 8b, 8c outputs the difference between the pixel signal currently input and the pixel signal input immediately before the pixel signal, and inputs the difference to the comparator 9. The comparator 9 compares the magnitudes of the outputs from the differentiators 8a, 8b, 8c with the three comparators 9a ₁ , 9a ₂ , 9a ₃ to compare the magnitudes of the spatial frequencies, and the signals as shown in Table 1 are compared. The gate circuit 9b ₁
Input into 9b ₂ and 9b ₃ . The gate circuits 9b ₁ , 9b ₂ , 9b ₃ receive the signals from the respective comparators 9a ₁ , 9a ₂ , 9a ₃ and output three signals as shown in Table 1. Switch receiving this signal
Any one of 10a, 10b, and 10c is turned on, and the pixel signal read from the frame memory connected to the switch that turned on is the frame memory for image synthesis in the subsequent stage.
Stored in 11.

For example, assume that the signal output from the differentiator 8b is the maximum. In this case, the comparators 9a ₁ , 9a ₂ and 9a ₃ output signals of "0", "1" and "1", respectively.
The pixel signal read from the MII is stored in the image compositing frame memory 11.

After this, in steps 9 and 10, the frame memories MI, MI
The addresses designated to the I, MIII and the image synthesizing frame memory 11 are increased, and the above steps 7 to 8 are repeated for all pixel signals for one frame. As a result, a clear image with a deep depth of focus is composited in the image composition frame memory 11 in any part of the subject.

Next, a second embodiment showing the principle of the present invention will be described with reference to FIGS. 3 and 4. The same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The second embodiment is different from the difference units 8a and 8a shown in the first embodiment.
The CPU 12 performs the discrimination by b and 8c and the comparator 9 and the selection by the selection circuit C, and its operation is as shown in the flowchart of FIG.

First, in steps 1 to 8, as in the first embodiment, 3
Imaging on planes I, II, III, storage of each image signal obtained in frame memories MI, MII, MIII, frame memories MI, MII, MI
Performs operations such as reading pixel signals from II. After this,
In step 9, the difference between the pixel signal read from each frame memory MI, MII, MIII and the pixel signal immediately before it is obtained. Then, of the differences, it is determined whether or not the difference in the frame memory MI is the maximum (step 10). If the difference is the maximum, the pixel signal from the frame memory MI is stored in the image compositing frame memory 11. (Step 11),
If it is not the maximum, in step 12, it is judged whether or not the difference in the frame memory MII is the maximum. If the difference in the frame memory MII is maximum, the pixel signal output from the frame memory MII is stored in the image compositing frame memory 11 (step 13). The signal is stored in the image compositing frame memory 11 (step 14). After that,
By steps 15 and 16, pixel signals for one frame are stored in the image compositing frame memory 11.

Next, a third embodiment showing the principle of the present invention will be described. In the third embodiment, instead of the comparator 9 in the first embodiment, magnitude comparators 14a, 14b, 14c for comparing the magnitudes of outputs a, b, c from the difference units 8a, 8b, 8c, and The comparator 16 including the ROM 15 from which the signals Sa, Sb, and Sc shown in Table 2 are read according to the output signal of FIG.

The signals Sa, Sb, Sc read from the ROM 15 are sent to the switch 10
It is input to a, 10b, 10c and this switch 10a, 10b.10c
Is ON when the input signals Sa, Sb, Sc are "1". The rest of the configuration is the same as that of the first embodiment, and it is possible to obtain a clear image with a deep depth of focus, as in the above embodiments.

In the above embodiment, the case where the image is picked up on three planes I, II, and III is shown, but in the characteristic embodiment of the present invention, the light is spatially divided by using a prism or the like, and three planes I, II, and II, III
An image is picked up by the three image pickup elements arranged above. Further, the number of image pickup planes is not limited to three and may be an arbitrary plurality of planes, but it is desirable to configure a plurality of planes. In any case, according to this characteristic embodiment of the present invention, the blurring does not occur even for a moving subject, so that the image quality is improved.

〔effect〕

As described above, according to the depth-of-focus correction apparatus of the present invention, not only the effect that the depth of focus can be corrected without changing the optical system, but also when a moving subject is imaged The images will not be misaligned when they are combined, and the combination will not fail.

[Brief description of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention, and FIG.
The figure is a flow chart showing the operation of the one shown in FIG.
FIG. 3 is a block diagram showing a second embodiment of the present invention, and FIG.
FIG. 5 is a flow chart of what is shown in FIG. 3, and FIG. 5 is a block diagram showing an essential part of a third embodiment of the present invention. 1 ... Subject 2 ... Imaging element (A ... imaging means) 4 ... Servo mechanism (A ... imaging means) 3 ... Optical system 8a, 8b, 8c ... Differentiator (B ... discrimination means) 9 , 16 …… Comparator (B …… discriminating means) 10a, 10b, 10c …… switch (selecting means C)

Claims (1)

[Claims] 1. An image separating means for spatially dividing light so as to separate an optical image from a subject incident through an optical system into a plurality of planes having different focal positions, and the image separating means. A plurality of image pickup means for picking up each image, and the spatial frequency in the same portion of the optical image picked up on each plane by the plurality of image pickup means are compared to determine the signal portion from the image pickup means having the maximum spatial frequency. A depth-of-focus correction device comprising: a discriminator, a selection unit that selectively extracts an image signal of a signal portion having the maximum spatial frequency, and a combination unit that combines the image signals selected by the selection unit.