JPH01147971A - Picture input device - Google Patents

Abstract

PURPOSE:To obtain a picture in focus with an object to be picked up entirely whose image pickup distance varies in excess of the focal point of an image forming lens by dividing a picture of plural distance image pickup devices into small areas and selecting only the picture in focus state from each small area and synthesizing the pictures. CONSTITUTION:One and same object to be picked up is picked up (1) on plural patterns corresponding to different focal distance in response to the focus range of an image forming lens. Then plural pictures picked up are divided (2) into plural same small areas to form a model picture with a small area corresponding to the image forming distance different from the image forming distance of the small area when the picture of the small area is supposed to be a focused picture. Then the model picture is compared (4) with the picture of a small area corresponding to that of the original picture to obtain an evaluation function. The model picture to minimize the evaluation function obtained in this way is found out to decide (5) the image forming distance. The procedure as above is applied to each small area and the picture is synthesized (8) for each picture of small area in the decided image forming distance.

Description

[Detailed Description of the Invention] [Summary] Regarding an image input device that can obtain an in-focus image over the entire surface of a target object having multiple height levels, the in-focus image can be obtained from images of a multi-distance imaging device. To make it possible to obtain a completely in-focus image even for an object to be imaged whose imaging distance changes beyond the depth of focus range of an imaging lens by selecting and compositing only two images. A plurality of distance imaging means for imaging an object to be imaged on a plurality of screens corresponding to different imaging distances; an image division means for dividing each of the plurality of images t into a plurality of small regions; Assuming that the focused image is an image of a small area, an image conversion means creates a model image of the corresponding small area at different imaging distances, and compares the model image with the original image of the corresponding small area to obtain an evaluation function value. an image comparison means for determining the imaging distance of the model image that minimizes the evaluation function value, and an image synthesis method for synthesizing images for each image in a small area of the determined imaging distance. and means.

[Industrial application field]

The present invention relates to an image input device that can obtain an image that is in focus over the entire surface of a target object having multiple height levels.

In an imaging device, when multiple target objects are located at different distances from the imaging lens, or when each part of the surface of the same target object is located at a different distance from the imaging lens, the distance If the difference is not within the depth of focus determined by the lens, it is usually not possible to clearly image all parts in focus.

However, in practice, it is necessary to obtain an image that is in focus over the entire area even when the range of the object to be imaged exceeds the focal depth range of the imaging lens. There are cases.

[Prior Art] Conventionally, methods for imaging such a wide range of objects include a method in which a sensor placed on an imaging plane is moved relative to a fixed imaging lens according to the imaging distance; A method has been used in which the optical path of an imaging lens is divided using a half mirror or the like, and sensors are placed at different imaging positions to take images.

FIG. 6 shows an example of a conventional multi-distance imaging device, in which the sensor is moved.

In FIG. 6, the imaging lens 11 is fixedly provided to the imaging device. On the imaging plane, the image is detected by a sensor 12 such as a CCU area sensor (video camera sensor), and the sensor 12 is mounted on a moving stage 13 and is configured to be movable according to the imaging distance. .

Now, from the center of the imaging lens 11 to the object to be imaged 141°1
The distance to 4-14a, that is, the imaging distance is al.

al, aj, and when the distance from the lens center to the imaging plane, that is, the imaging distance, is bIs b** ba, the moving stage 13 is controlled to change the imaging distance a1 to
If the object to be imaged is moved so that the imaging distance becomes 14. Focused images can be obtained for all of the 141 to 141 rows.

FIG. 7 shows another example of a conventional multi-distance imaging device, in which a plurality of sensors are used.

In FIG. 7, the optical path of the imaging lens 11 is divided by half mirrors 15, 15, and each sensor 1
21, 12! -12 m, but at this time, each sensor 12. .

Distance to 12g and 12j, that is, imaging distance bl+bl
+b1 is the object to be imaged 141 w 141 + 14m
The distance to , that is, the imaging distance is selected so that it becomes the same focusing distance as ale"te"j. Therefore, also in the case of FIG. 7, the imaged object 14. Focused images can be obtained for all of the 143 to 143 rows.

[Problem that the invention seeks to solve]

In the conventional multi-distance imaging device as shown in FIGS. 6 and 7, it is possible to image an object to be imaged at an imaging distance corresponding to a certain imaging distance in a focused state. However, objects to be imaged at other imaging distances are not within the focal depth range of the imaging lens, and therefore cannot be imaged in focus.

FIG. 8 shows an example of an image taken by a conventional multi-distance imaging device, in which (a) shows the relationship between the imaging device and the object to be imaged. Side 1
6 is tilted from the vertical, the imaging distance differs for each part of the surface 16. Each part of the present 16 161 + 16 goose *
It is assumed that the imaging distance is gradually decreased from 16 m.
When the imaging distance is set according to each imaging distance,
The images on the sensor 12 are (b), (c), (
dl. In each image, a position 161 , 161 corresponding to the imaging distance.

The portion corresponding to 161 is in focus, but the other portions are out of focus and a clear image cannot be obtained.

The present invention aims to solve such problems, and by selecting and combining only in-focus images from images taken by a multi-distance imaging device, the imaging distance can be adjusted to the depth of focus of the imaging lens. The object of the present invention is to make it possible to obtain a completely focused image even for an object to be imaged that changes over a range.

[Means for solving problems]

FIG. 1 shows the basic configuration of the present invention, which includes a multi-distance imaging means 1, an image dividing means 2, an image converting means 3, an image comparing means 4, a determining means 5, and an image combining means. means 6.

The multi-distance imaging means 1 images the object to be imaged on a plurality of screens corresponding to different distances to the east.

The image dividing means 2 divides each of the plurality of captured images into a plurality of small regions.

The image conversion means 3 creates model images of the corresponding small area at different imaging distances, assuming that the image of the small area is a focused image.

The image comparing means 4 compares the model image with the original image of the corresponding small area to obtain an evaluation function value.

The determining means 5 determines the imaging distance of the model image that minimizes the evaluation function value.

The image synthesizing means 6 synthesizes images for each image of the small area having the determined imaging distance.

[Effect]

The same object to be imaged is imaged on a plurality of screens corresponding to different imaging distances depending on the focal depth range of an imaging lens. The plurality of captured images are then divided into the same plurality of small regions. For each small area divided in this way, a model image of the corresponding small area is created at an imaging distance that is different from the image forming distance of this small area when the image of this small area is assumed to be the focused image. . This model image is then compared with the image of the corresponding small area in the original image to determine the value of the evaluation function. A model image with the minimum evaluation function value is found and its imaging distance is determined. Such a procedure is performed for each small area, and an image is synthesized for each image of the small area at the determined imaging distance. In this image, the one in which each of the divided small regions is closest to the in-focus state is selected, and therefore, in the combined image, all of its parts are in the in-focus state. In this way, it is possible to obtain a fully focused image even for an object to be imaged whose imaging distance to the object varies beyond the depth of focus range of the imaging lens.

〔Example〕

FIG. 2 is a block diagram showing the overall configuration of an embodiment of the present invention. In the figure, reference numeral 21 denotes a multi-range imaging device, which has a sharpening configuration shown in FIG. 6 or 7, etc.
It includes an imaging lens and a sensor such as a CCD area sensor, and can obtain n images corresponding to n imaging distances. 22 is an image input circuit that digitizes the image signal obtained from the imaging device 21 and outputs it for each image. This signal is input to the original image memory 23 consisting of n planes and stored for each image.

In the embodiment shown in FIG. 2, in order to perform further image processing, an image blurring circuit 249, an image comparison circuit≦5° determination circuit 2,
61 image synthesis circuit 279 and a synthesis image memory 28, each part is connected to each other via a bus 29, and is configured to operate according to a constant sequence under the control of a control circuit 30.

FIG. 3 shows a configuration for image processing in the embodiment shown in FIG. 2, and the same parts as in FIG. 2 are designated by the same numbers.

Different imaging distances for imaging by the imaging device 21
The image is stored in the n-plane frame memory 231 as described above.
An original image memory 23 consisting of .about.23n is stored for each K image. The images in each of the memories 231 to 23n are divided into a plurality of small areas, and the image in the corresponding small area of each image is read out and input to the image blurring circuit 24.

FIG. 4 explains image division, and shows that by dividing one screen into, for example, M vertically and N horizontally, M x N small areas can be obtained. .

In the image blurring circuit 24, for the n corresponding input small area images, other small areas having different imaging distances are assumed to be in the focused position. Create a model image for the image.

FIG. 5 explains the creation of a blurred image. In the same figure, (a) shows a two-dimensional image at each imaging distance, and...' bi-1e bit bt+I I ”
It is assumed that the imaging distance from the continuous imaging lens becomes smaller (the imaging distance becomes larger), and 1) i is the distance corresponding to the in-focus position. (b) shows the human power level (sensor output), and it is shown that it has a sharp fall for the image at the in-focus position (indicated by a black circle), but that fall at the out-of-focus position. The descent is gradual.

On the other hand, assuming that a certain image plane p is in focus, let frlpl(X*Y) be the analytically obtained sensor output corresponding to a different image plane q. Here, X and Y represent the coordinates of a small area on the screen.

The creation of such an image can be performed by known means, such as mathematical techniques or optical path tracing.

In Figure 5, (C) shows each distance when the imaging distance bt-t is the focusing position. *bl-1-k)1 e
bt+1 * '...'s light 1-1 i
i+1 Bell"", m,, , m4. −, , ffl,
-1s"', and (d) shows the original level of each distance when the imaging distance bl is the focus position.
1+1...1 mt * mt * rf)t t...
・This shows the following.

The image comparison circuit 25 compares the original level m in the blurred image thus created with the observed original level e, and evaluates the degree of approximation using the following evaluation function.

When such an evaluation is performed, the plane where the evaluation function Ep takes the minimum value can be regarded as the in-focus plane.

In FIG. 5(d), the model m1 obtained with bl as the focal position is the sharpest, and it is shown that the imaging distance bl is evaluated to be appropriate as the focal position.

The determination circuit 26 determines the evaluation function obtained in the image blurring circuit 25, and stores the memory 23. Determine ~23n.

The image synthesis circuit 27 reads out the image signal of the small area thus determined from its memory and writes it into the corresponding position in the synthesized image memory 28.

The control circuit 30 outputs an image signal from the composite image memory 28 after completing such processing for all small areas of the image in the original image memory and completing writing of all areas in the composite image memory 28. . This image is a desired image and is composed only of small areas in focus.

〔Effect of the invention〕

As explained above, according to the present invention, a desired image is obtained by dividing an image from a multi-distance imaging device into small regions, and selecting and combining only in-focus images from each small region. Therefore, it is possible to obtain a fully focused image even for an object to be imaged whose imaging distance changes beyond the depth of focus range of the imaging lens.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of the present invention, FIG. 2 is a diagram showing the overall configuration of an embodiment of the present invention, and FIG. 6 is a configuration for image processing similar to the embodiment of FIG. 2. 4 is a diagram illustrating image division, 5 is a diagram illustrating creation of a blurred image, 6 is a diagram illustrating an example of a conventional multiple distance imaging device, and 7 is a diagram illustrating conventional FIG. 8 is a diagram showing an example of an image obtained by a conventional multi-distance imaging device. 21...Multiple distance imaging device 22...Image input circuit 23...Original image memory 24...Image blurring circuit 25...Image comparison circuit 26-...Judgment circuit 27...Image synthesis circuit 28 ... Composite image memory 29 ... Bus 30 ... Control circuit

Claims (1)

[Scope of Claims] Multi-distance imaging means (1) that images an object to be imaged on a plurality of screens corresponding to different imaging distances, and an image that divides each of the plurality of images into a plurality of small regions. Splitting means (
2); image conversion means (3) for creating model images of the corresponding small area at different imaging distances when the image of the small area is assumed to be a focused image; An image comparing means (4) for comparing with the image to obtain an evaluation function value, and a determining means (4) for determining the imaging distance of the model image where the evaluation function value is the minimum.
5); and image compositing means (5) for composing images for each image of a small area having the determined imaging distance.