JPS61157080A - Electronic camera - Google Patents

Abstract

PURPOSE:To obtain the focused pictures of subjects having different distances by changing a relative distance between a lens system and an image pickup element so as to divide the image pickup surface of the image pickup element into plural areas and synthesizing picture information with the highest contrast. CONSTITUTION:Signal charged arising in picture element groups 111-1MN are outputted from a horizontal CCD shift register 3 in terms of time series, and stored in a picture memory 5 through an arithmetic circuit 4. Picture information built-in the previous state is sequentially outputted at every line in synchronizing with the horizontal CCD shift register 3, and the arithmetic circuit 4 compares said information with that having a different focusing position in the same picture element. The difference of the output values between adjacent picture elements gives the contrast information at the position, and the larger output difference turns out to be a signal nearer to the focusing point. Accordingly the position of the lens system is sequentially changed, whereby a focused image from a near focusing point to far one can be obtained.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention also relates to an electronic camera using an image sensor.
Therefore, it particularly relates to an imaging method that focuses on objects both near and far.

[Technical background of the invention and its problems]

An electronic camera is equipped with an image sensor in place of the film in a normal camera, and stores image information obtained from the image sensor in an image memory. FIG. 3 shows a schematic configuration of such an electronic camera. In the figure, 1 is the main body of the camera, 12 is a lens, and 13 is an image sensor.

In the above configuration, the lens 12 and the image sensor I3
By changing the relative distance to the subject 15. ．． 15□
Or 15. Focus with the camera.

FIG. 4 shows the configuration of the image sensor.

In other words, pixels 1G, 16 arranged in a matrix
．． There are vertical CCD shift registers 17, 17, . . . between each column. ... are provided, and the pixels 16, 16 .
The signal charges obtained from ... are time-seriesized for each column and supplied to the horizontal CCQ shift register 18. Then, each of the vertical COD shift registers 17, 17 .・・・
The transferred signal charges are time-series by the horizontal CCD shift register 18 to obtain image information OUT.By the way, when photographing a subject with depth as shown in FIG. Because there is a depth of field, a zero point does not fit for the entire distance C, and depending on the relative distance between the lens 12 and the image sensor 13, for example,
As shown in +), near-focus, intermediate-focus, and far-focus images are obtained.

In FIGS. 6(a) to 6(C), solid lines indicate in-focus images, and broken lines indicate out-of-focus images.

In this manner, when a conventional camera focuses on a certain subject, objects that are outside the depth of field (depth of focus) in front and behind it are not in focus.

[Purpose of the invention]

This invention was made in view of the above circumstances,
The purpose is to provide an electronic camera that can obtain in-focus images even when objects are at different distances.

[Overview of the invention]

That is, in this invention, in order to achieve the above object, the relative distance between the lens system and the image sensor is changed to obtain image information at a plurality of focal positions from a near focus to a far focus, and image information of the image sensor is obtained. A subject image is obtained by dividing the surface into a plurality of regions, comparing the image information at each focal position for each corresponding image region, and synthesizing the image information with the highest contrast of each image region at each focal position. Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an image sensor (solid-state image sensor) and an image memory section of an electronic camera. The subject image is formed on a two-dimensionally arranged pixel group 1.1 to 1. Vertical CCD shift register groups 2° to 2M are arranged between each of the pixel columns, and the pixel groups 11. - Sequentially transfer signal charges corresponding to optical signals (image signals) generated at JMN. Above vertical CCD register group 2, ~2M
A horizontal COD shift register 3 is provided at one end, and sequentially transfers the signal charges transferred by each of the vertical CCD shift register groups 2I to 2M.

Now, if an image is taken with the lens system at its closest focus (L=1), pixel group 11. The signal charges generated in ~IMN (signal charges on the n-th line are indicated by z+(n)) are output from the horizontal COD shift register 3 in time series.

These signal charges are then stored in the image memory 5 as image information via the arithmetic circuit 4.

To store the image information in the image memory 5, input CC
D A shift register 6 is used, and each line is sequentially stored.

Next, image is taken in the state C1=2) in which the lens system is shifted one step from the near focal point, and as before, the horizontal CCD
From the shift register 3, charge signal processing t(
n) output. At this time, from the output CCD shift register 7 provided at the bottom of the image memory section 5,
The image information stored in the image memory in the previous state (i=x) is sequentially output as image information R1(n) for each line in synchronization with the horizontal CCD shift register 3. This horizontal COD shift register 3 and each image signal from the output CCD shift register 7 are synchronized, and the movable contact 8a of the changeover switch 8 is connected to the fixed contact 8b.
By connecting to both sides, the arithmetic circuit 4 can compare image information of different focal positions in the same pixel.

In this state, the arithmetic circuit 4 calculates the image information R1-1(n) of the n-th line image and the horizontal COD of the n-th line.
The image information l1(n) from the shift register 3 is compared.

Next, FIG. 2 (
This will be explained with reference to a) to (C). (a) Figure and (b)
J diagrams respectively show the image information Ij(n) of the n-th line output from the horizontal COD register 3 and the output C
These (De
w image information l1(n) l R1-1(n) is supplied to the fL calculation circuit 4. Both information IL(n) and Rj-1(
In case n), since the focal position of the lens is shifted by one step, the image rotor changes depending on how the lens is focused.

Here, the difference in output values between adjacent pixels provides contrast information depending on their positions. Therefore, IL(n) and nt-
, (n), and select the larger contrast information value (selecting the one with the larger difference in output between adjacent pixels), as shown in Figure 2(c). As a result, a signal RL(n) closer to the in-focus point can be obtained.

The above-mentioned operation is repeated until the far focal point is reached by sequentially changing the position of the lens system. After that, the movable contact 8a of the changeover switch 8
is connected to the fixed contact 8c side and image information is read out from the image memory section 5 via the output CCD shift register, a focused image from near focus to far focus is obtained.

In the above embodiment, the image information with the lens position shifted was compared by using the same image sensor and storing one image in the image memory unit. It is also possible to arrange several image sensors and extract the maximum contrast information from the image information obtained from each image sensor.

In addition, the contrast information may be extracted by comparing contrast information within a predetermined area, instead of comparing the contrast information for each pixel by taking the output difference between adjacent pixels as described above.

Furthermore, the image memory section may be formed on the same chip as the solid-state image sensor, or may be formed on a separate chip,
An image pickup tube may be used instead of the solid-state image sensor.

〔Effect of the invention〕
As described above, according to the present invention, it is possible to provide an electronic camera that can obtain in-focus images even when objects are at different distances.

[Brief explanation of the drawing]

FIG. 1 (J is a diagram for explaining an electronic camera according to an embodiment of the present invention, FIG. 2 is the above-mentioned figure): A diagram for explaining the operation performed by the arithmetic circuit at z, FIG.
The figure is a schematic configuration diagram of an electronic camera, Figure 4 is a diagram showing the configuration of the image sensor in Figure 3 above, Figure 5 is a diagram showing an example of a subject, and Figure 6 is an image obtained at each focal position. It is a diagram. 12...Lens, 13...Image sensor, 15++15□
, 15, . . . subject, 11. ~ IMN... Pixel group, 21-2M... Vertical CCD shift register group, 3... Horizontal CCD shift register, 4... Arithmetic circuit, 5... Image memory, 6... Input COD
Shift register, 7... CCD shift register for output, 8... Selector switch. Applicant's agent Patent attorney Takehiko Suzue No. 2 Figure 5 Figure 6 Procedural amendment tts* 6Q, "jOa

Claims (1)

[Claims] A subject image is formed on an imaging device via a lens system, the image information obtained from this imaging device is recorded in an image memory, and the image information in this image memory is output as a hard copy of the subject image to the outside. In an electronic camera, a means for obtaining image information at a plurality of focal positions from a near focus to a far focus by changing the relative distance between a lens system and an imaging device, and a means for obtaining image information at a plurality of focal positions from a near focus to a far focus, and dividing an imaging surface of the imaging device into a plurality of image areas. ,
a comparison means for comparing the image information at each focal position for each corresponding image area, and image information with the highest contrast of each image area at each focal position based on the output of this comparison means, and the selected image information is 1. An electronic camera comprising means for synthesizing image information to obtain a subject image.