JP2003262909A - Electronic camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make easily judgeable whether or not a subject is brought into a focused state without depending on the individual skill of a photographer. <P>SOLUTION: A control part 19 performs an edge deciding processing and warning processing based on edge detection data transmitted from an image signal processing part 14. Whether the edge whose length is equal to or above a specified length exists all over the image pickup plane is detected. When the edge whose length is equal to or above the specified length does not exist at all, a high-strength warning is issued. The pairing property in the direction of the edge is judged. When the pairing property in the direction of the edge is not found at all, it is judged as a situation that the subject is not normally brought into focus, so that a middle-strength warning is issued at a step 32. A specified area on the image pickup plane is enlarged. Whether or not the sharpness of the edge is equal to or above a specified value is judged concerning the enlarged specified part, and a warning is issued when the specified sharpness is not found. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera for detecting whether a focus is good or bad.

[0002]

2. Description of the Related Art In recent years, electronic still photography using an electronic camera has become widespread. Electronic cameras use CCD (Charged 1) to capture the optical image formed by an optical lens that captures the subject.
Coupled Device) After photoelectric conversion by a camera, image processing of the electric signal is performed and conversion into digital image data, the captured image can be displayed on a display device or stored in a storage device as digital data.

The advantages of electronic still photography over silver halide photography are that they can be stored as digital image data, there is no deterioration in image quality due to aging, and that image processing is easy. Furthermore, unlike silver halide photography, it is not necessary to develop the film, so you can check the photographic image immediately after shooting, and it is also a great advantage that you can delete unnecessary images such as out of focus and retake them. Is. However, since a display device such as a liquid crystal monitor usually attached to an electronic camera is limited in size and resolution, the photographer cannot perceive a defect such as a focus shift simply by displaying the captured image as it is on the display device. There are many things.

As an example of solving such a problem,
There is JP-A-11-196301. In the publication, as shown in FIG. 11A, a monitor image of a subject displayed during image recording is selected and an image portion in a focus frame 81 for focus confirmation is selected and enlarged, and a portion 83 or all of the screen is displayed. 82 (FIG. 11 (b),
(b ')). The user can refocus and reshoot the image by looking at the enlarged image. A re-captured image 84 is shown in FIG.

[0005]

However, in Japanese Unexamined Patent Publication No. 11-196301, it is easy to confirm the state of focus deviation or blurring by enlarging a part of the display screen. If you just enlarge the focus position of the subject, you may miss a slight defocus or blur. Further, since the subtle focus deviation and the recognition of the blur depend on the subjectivity of the photographer, there is a problem that the degree of recognition varies depending on the skill of each photographer. It is an important concern for the photographer whether or not the subject is in focus accurately, especially when there is a possibility that the autofocus function may become insufficient, such as when shooting at night, the focus pass / fail judgment is performed. Effectiveness is high.

Therefore, in order to solve the above problems, an object of the present invention is to provide an electronic camera capable of easily determining whether a subject is in focus or not, regardless of the photographer's personal skill. To do.

[0007]

The present invention is an electronic camera that captures a subject image and stores it in a recording medium.
An edge detection unit that detects an edge from the captured subject image and outputs detection data; a determination unit that determines the focus degree of focus based on the edge detection data;
A warning means for changing the degree of warning according to the degree of focus of the focus is provided.

The determining means is characterized by the sharpness, length, and
It is characterized in that the focus degree is determined by at least one of the directions. Further, the edge detecting means detects the specific area of the captured subject image.

The warning means may issue a warning when the sharpness of the edge is less than a predetermined sharpness as a result of the determination, and the length of the edge is a predetermined length. A warning may be issued if there is no edge longer than the length, a warning may be issued if there is no pair of edges in the direction, and the determination result by the determination means is displayed. The degree of warning may be changed according to the result of the calculation based on a predetermined rule.

In the present invention, in consideration of the case where an ordinary photographer uses an electronic camera or the like, the focus degree of focus is determined and a warning such as an alarm is issued. First, an edge is detected from a subject image by the method of Japanese Patent Laid-Open No. 2000-172855, and the sharpness, length and direction are determined. That is, a threshold value used for edge determination is determined from the variation of pixels in the edge detection direction, and edge detection is performed based on this threshold value.
At this time, edge detection may be performed uniformly on the entire screen,
Edge detection may be performed by enlarging a specific area. In particular, with respect to sharpness, it is preferable to attach importance to edge detection of a specific area and to detect edge of the entire screen with respect to length and direction.

This is because in the case of normal photographing, it is usual to select a person or landscape as a subject. At this time, the edge has a certain length and a certain direction. Furthermore, the edges of the subject are paired in the vertical direction. For example, there is at least one pair in men's pants and women's skirts. Also, as there is at least one pair in a mountain or a tower, the pairing property is generally found in people, buildings, landscapes, etc.

That is, first, it is determined whether or not the focus is achieved by the presence or absence of the edge, and when it is determined that the focus may be achieved (the edge is present), the sharpness of the edge, the length,
The pairing of directions is calculated according to a predetermined rule, and the degree of warning is changed based on the result, so that the photographer recognizes the degree of focus.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of a captured image of a subject according to the present invention, and FIG. 2 is an enlarged view of a specific portion of the captured image of the subject shown in FIG.

In FIG. 1, an image 1a taken by the electronic camera of the present invention is an image displayed on the image display section.
The image 1a is composed of a lecturer 4 who is on the podium and two audiences 5 and 6, and is an image taken by focusing on the part 2a of the lecturer 4. In FIG. 2, an image 2b is an enlarged view of the specific portion 2a in focus in FIG. 1, and intersects with a horizontal dotted line 8 as an example of an edge.
There are edges 7a and edges 7b in the vertical direction.

FIG. 3 is a block diagram showing the structure of the electronic camera according to the present invention. An example of the structure of the electronic camera of the present invention will be described with reference to FIG. The imaging unit 11 is composed of an optical system lens and a CCD, and an optical image of a subject is captured by the CCD.
Each of the R, G, and B pixels is photoelectrically converted and sent to the image pickup signal processing unit 12 as a charge signal. The imaging signal processing unit 12 performs signal processing such as gamma correction and white balance correction on the charge signal, and temporarily stores image data such as JPEG in the frame storage unit 13. Frame storage unit 1
The image data stored in No. 3 is displayed on the image display unit 15 via the control unit 19. Further, the image data is sent to the image signal processing unit 14, and the image data is analyzed to perform processing such as edge detection. The edge detection data output from the image signal processing unit 14 is determined by the control unit 19 as to whether or not it is in focus. If the edge detection data is out of focus, the warning display unit 18 notifies the photographer. It

The control unit 19 controls not only the judgment function concerning the notification of the warning information but also each processing unit constituting the electronic camera. The input unit 16 has an input function such as buttons and dials for the photographer to operate the electronic camera, and also serves as an interface for transmitting the input action of the photographer to the control unit. The auxiliary storage unit 17 is composed of a removable storage medium such as a flash memory, and has a function of saving a captured image. The warning display unit 18 has a function of making the photographer recognize the warning. In addition to the LED lamp indicating the warning, the warning display unit 18 also has an alarm voicing function for making a sound notification to the photographer. Further, the image display unit 15 may also serve as the warning display unit 18, and it is also possible to display the image on the imaging screen in a superimposed manner.

FIG. 4 is a flow chart of the operation of the electronic camera according to the present invention, and FIG. 5 is a flow chart showing in detail the edge determination, focus acceptance / rejection determination processing and warning processing of the electronic camera according to the present invention. The operation flow of the electronic camera of the present invention will be described with reference to FIGS. 4 and 5.

First, the electronic camera has an optical system lens and a CCD.
An image is picked up by focusing on a part of the subject by the image pickup unit 11 including a camera (step S1).
1). Next, the picked-up image is processed by the pick-up signal processing unit 12 to process the RGB signals of the CCD camera into an image format such as JPEG which can be displayed on the screen display unit 15, and is temporarily stored in the frame storage unit 13. Memorized in. The image stored in the frame storage unit 13 is displayed on the image display unit 15 under the control of the control unit 19 (step S1).
2).

Next, the photographer determines whether or not to perform the focus determination process (step S13). When the photographer intentionally blurs the subject, the focus determination process is not performed, so the process proceeds to step S17. When the focus determination process is performed, the edge detection process of step S14 is performed. In the edge detection process, the image signal processing unit 14 analyzes the image data sent from the frame storage unit 13 to detect an edge. A specific edge detection method is disclosed in JP 2000
The method of 172855 can be used.
That is, a threshold value used for edge determination is determined from the variation of pixels in the edge detection direction, and edge detection is performed based on this threshold value.

Next, the control section 19 performs edge determination processing and warning processing based on the edge detection data sent from the image signal processing section 14 (step S15). In the edge determination processing, the warning points are initially set (step S21). Here, the initial value of the warning point is Y0. Next, it is determined whether or not there is an edge in the captured image (step S22), and if there is no edge, a warning of strength is issued from the warning display unit 18 (step S3).
1) Make the photographer recognize that the subject is out of focus. As an example where there is no edge, the case where the focus is out of focus as a whole is main. In other special cases,
It is possible that the photograph was taken of a clear sky or a solid white wall, but this can be easily determined by the photographer depending on the composition at the time of shooting.

Next, in step S23, it is detected whether an edge having a predetermined length or more exists in the entire image pickup screen. The purpose of detecting an edge having a predetermined length is to detect a small edge of about 2 to 3 pixels, noise, etc. may have been detected, and it is often not the original edge. Also, as can be easily analogized, many vertical edges are seen in people and landscapes, and these are usually at least ¼ of the vertical length of the screen. If there is no edge longer than the predetermined length, an intensity warning is issued in step S31. If there is an edge longer than the predetermined length, the warning points are changed from Y0 to A1 according to the maximum length of the edge. Only (reduce) operation (step S24), step S
Go to 25. Here, the warning point after the operation is set to Y1 in step S24.

In step S25, the pairing property in the edge direction is determined. As mentioned above, in normal shooting, at least 1
Although there is a pair of pairs, this pair is usually located at the center of the vertically divided screen, and this point is also taken into consideration in the determination of the pairness. If there is no pairing in the direction of the edge, it can be determined that the image is not in focus normally, so a moderate warning is issued in step 32. If there is a pair of directions, the warning points are changed from Y1 to A2 according to the number of pairs.
Only (reduce) operation (step S26), and the process proceeds to step S27. Here, the warning point after the operation is set to Y2 in step S26.

Next, enlargement is performed on a specific area on the captured image. (For example, in the example of FIG. 2, the focused portion 2a is enlarged as an image 2b.) The purpose of using the enlarged image for edge detection is that the range in which the electronic camera focuses is not the entire screen in many cases. Due to.
In particular, when the aperture is widened, the area in focus is inevitably narrowed, and the sharpness of the edges at both ends of the screen drops, so it is not appropriate to judge the sharpness of the entire screen.

It is judged whether or not the sharpness of the edge is greater than or equal to a predetermined amount with respect to this enlarged specific portion (step S28). If there is no predetermined sharpness, step S28 is performed.
At 32, a moderate warning is issued, and when the sharpness is equal to or higher than a predetermined sharpness, the warning point Y2 is operated (reduced) by A3 according to the sharpness (step S29). Here, the warning point after the operation in step S29 is set to Y3. That is, the final warning point is Y3, and Y3 = Y0-
It can be expressed by A1-A2-A3.

Next, in step S30, when the final warning point Y3 has a certain warning point or more, in order to make the photographer recognize that the focus may not be in focus in step S33. Issue a weak warning. If the warning point Y3 has not reached a certain warning point or more, no warning is given and the process proceeds to step S16. In step S16, the photographer determines whether or not to continue shooting. If shooting is to continue, the process returns to step S11. If shooting is not continued, the process ends.

According to the electronic camera of the present invention, it is first determined whether or not the focus is achieved by the presence or absence of the edge, and when it is determined that the focus may be achieved (the presence of the edge), the sharpness and the length of the edge are determined. It is possible to make the photographer recognize whether or not the focus is acceptable by calculating the pairing of the direction and the direction according to a predetermined rule and changing the degree of warning based on the result.
That is, it is possible to easily determine whether or not the subject is in focus regardless of the skill of the photographer who is involved in the focus. In particular, it is effective when there is a high possibility that the autofocus function will be insufficient at night, or when there is a slight focus shift and it is difficult to make a judgment only with the monitor display image.

Next, referring to FIG. 5 to FIG.
An example of a specific method of calculating a warning point will be described for an image captured with 600 pixels in the vertical direction. First, in step S21, the initial value Y0 of the warning points is set to 10 points. At step S22, the edge of the image is tried to be detected. Since the edge is detected, the process proceeds to step S23. In step S23, it is detected whether the maximum edge length existing in the image is equal to or longer than a predetermined length (L1).

FIG. 6 is a diagram showing criteria for judging a point operation according to the length of an edge. When the maximum edge length L1 existing in the image is 300 pixels, the point operation of point Y1 = Y0-3 is performed, so Y1 becomes 7 points (step S24).

Next, the pairing in the edge direction is detected (step S25), and the warning point is operated according to the number (D1) of the pairing in the edge direction (step S26).
FIG. 7 is a diagram showing a judgment criterion based on the number of pairs in the edge direction. If there are eight P1s in the image, the point operation of point Y2 = Y1-0 is performed, so Y2 becomes 7 points (step S26).

Next, a specific area (area where the photographer tries to focus) on the screen is enlarged (step S
27), the edge having the lowest sharpness is detected among the edges existing in the specific area (step S28), and the warning point is operated (step S29). FIG. 8 is a diagram showing a criterion for determining the sharpness of an edge, and FIG. 9 is a diagram showing an example of a method for determining the sharpness.

In FIG. 9, since the edge is located between the pixels P3 and P4, several pixels are extracted from P3 to the left and several pixels to the right to extract pixels P1 to P4.
6 forms one pixel column. In FIG. 9, the pixel row is composed of 3 pixels on each side of the edge,
The number of pixels forming the pixel row is increased or decreased according to the brightness distribution.

Next, the brightness data for each pixel existing in the specific area is extracted to find the maximum and minimum values of brightness, and a first threshold value is set between the minimum and maximum values of brightness. The second threshold value is set between the first threshold value and the maximum value. The setting of the first threshold value and the second threshold value is performed in consideration of the luminance distribution around the edge.

Next, the number of pixels (T1) existing between the first threshold value and the second threshold value is counted. In FIG. 9, since the number of pixels existing between the first threshold value and the second site is two, Y3 is determined according to the determination criteria shown in FIG.
= Perform point operation Y2-2. As a result, Y3 is 5 points. Since the edge sharpness is determined based on the number of pixels in this way, the determination can be easily performed.

Next, it is determined whether the warning points are below a certain level (step S30). FIG. 10 is a diagram showing the criteria for determining the warning points, and according to FIG.
Since 3 is 5 points, the process proceeds to step S33 and the photographer is warned of the degree of weakness.

[0035]

As described above, according to the electronic camera of the present invention, a general photographer can easily recognize whether the image is in focus or not. Therefore, if the image is out of focus, re-shooting or in-focus is achieved. Nevertheless, since it is not necessary to perform reshooting, the efficiency of electronic camera shooting can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a captured image of a subject according to the present invention.

FIG. 2 is an enlarged view of a specific portion of a captured image of the subject shown in FIG.

FIG. 3 is a block diagram showing a configuration of an image pickup apparatus according to the present invention.

FIG. 4 is a flowchart relating to a shooting operation of the electronic camera according to the present invention.

FIG. 5 is a flowchart showing in detail the edge determination, focus determination processing, and warning processing of the electronic camera according to the present invention.

FIG. 6 is a diagram showing criteria for determining a point operation based on the length of an edge.

FIG. 7 is a diagram showing a judgment criterion based on the number of pairs of edge direction.

FIG. 8 is a diagram showing a judgment standard based on a sharpness of an edge.

FIG. 9 is a diagram showing an example of a method of determining the sharpness of an edge.

FIG. 10 is a diagram showing a criterion for determining the sharpness of an edge.

FIG. 11 is a diagram showing an example of a conventional electronic camera.

[Explanation of symbols]

1a Captured image 2a Specific part of captured image 2b 2a enlarged image 3a, 3b edge 7a, 7b Vertical edge 8 Auxiliary line showing the crossing direction of edge 11 Imaging unit 12 Imaging signal processing unit 13 frame storage 14 Image signal processing unit 15 Image display section 16 Input section 17 Auxiliary storage 18 Warning display 19 Control unit

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) H04N 5/232 G02B 7/11 D // H04N 101: 00 G03B 3/00 AF term (reference) 2H011 AA03 BA31 BB04 DA05 2H051 AA00 BA47 CE14 CE16 DA26 DA32 DB01 GA13 GA19 2H102 AA33 AA34 BA01 BB05 BB08 BB32 5C022 AA13 AB21 AC03 AC18

Claims (7)

[Claims] 1. An electronic camera for capturing a subject image and storing the same in a recording medium, the edge detecting unit detecting an edge from the captured subject image and outputting detection data, and based on the edge detection data, An electronic camera comprising: a determination unit that determines a focus degree of focus; and a warning unit that changes a degree of warning according to the focus degree of the focus. 2. The electronic camera according to claim 1, wherein the determination unit determines the focus degree of focus based on at least one of the sharpness, length, and direction of the edge. 3. The electronic camera according to claim 1, wherein the edge detection unit detects a specific area of the captured subject image. 4. The warning device according to claim 1, wherein the warning means issues a warning when the sharpness of the edge is less than or equal to a predetermined sharpness as a result of the determination. Electronic camera described. 5. The length of the edge of the warning means is
4. The electronic camera according to claim 1, wherein a warning is issued when there is no edge longer than a predetermined length. 6. The electronic camera according to claim 1, wherein the warning means issues a warning when there is no pair of edge directions. 7. The warning means calculates the judgment result of the judgment means according to a predetermined rule, and changes the degree of warning based on the calculation result. Electronic camera.