JP3985448B2 - Imaging apparatus, imaging method, and recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging apparatus and an imaging method such as a digital still camera having an autofocus function.
[0002]
[Prior art]
Regardless of whether the camera is a silver salt camera or a digital still camera, almost all models of cameras that capture recent still images are equipped with an AF (autofocus) function. This autofocus function is used to shoot automatically by selecting either the center position of the screen or a plurality of specific positions, and an image in the focused state intended by the photographer is not necessarily obtained. Not always.
[0003]
Therefore, autofocus and manual focus can be switched between auto focus and manual focus, as used in many single-lens reflex type silver halide cameras / digital still cameras. It is also possible to obtain an arbitrary in-focus state without using the function.
[0004]
[Problems to be solved by the invention]
However, as described above, a camera that does not have a manual focus function cannot obtain an arbitrary in-focus state as described above, so it must inevitably perform shooting based on the autofocus function of the camera.
[0005]
Even if the camera has a manual focus function, it is difficult to check the exact focus state unless it has a sufficiently bright optical viewfinder. Since it was developed on the premise that it is used for autofocusing, the focus ring of the lens barrel is narrow, and there are some cases where operability in manual focus is extremely bad. As a result, the autofocus function and manual focus function are The models that can be easily switched and used comfortably are very limited.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an imaging apparatus and an imaging method capable of obtaining a still image in a desired in-focus state with a simpler operation. There is.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, the detection means for calculating the evaluation value for evaluating the degree of focus of the optical image incident on the image sensor via the optical lens system, and the drive position of the lens optical system are varied to a first imaging control means for taking up the time of image of the evaluation value, Ri Do the depth of field outside the drive position of the maximum time of the lens optical system of the evaluation value and the evaluation value is a predetermined value And a second imaging control unit that drives the lens optical system to take an image at the above position, and is operated by the first imaging control unit and the second imaging control unit by the shutter button operation of the photographer. It is characterized by taking a picture .
[0008]
With such a configuration, since a plurality of images including an image out of the depth of field are taken continuously by a single shutter key operation, a desired focus can be achieved with a simpler operation. The possibility that a still image in a state can be obtained can be increased.
[0009]
According to a second aspect of the present invention, there is provided a detection step for calculating an evaluation value for evaluating a degree of focusing of a light image incident on the image pickup device via the optical lens system, and the driving position of the lens optical system is varied to change the position. a first imaging control step of capturing the maximum time of image of the evaluation value, Ri Do the depth of field outside the drive position of the maximum time of the lens optical system of the evaluation value and the evaluation value is a predetermined value And a second imaging control step for driving the lens optical system to take an image at the position as described above .
[0010]
With such a configuration, a plurality of images including an image out of the depth of field are continuously photographed by one shutter key operation, so that a still image in a desired in-focus state can be obtained. The possibility that it can be obtained can be increased.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in the case where the present invention is applied to a digital still camera having a contrast type automatic focusing function will be described below with reference to the drawings.
[0016]
FIG. 1 particularly shows the configuration of the imaging system. Reference numeral 11 denotes a lens optical system provided in a lens barrel (not shown). When the optical image obtained by the lens optical system 11 is formed on the CCD 12 which is an image sensor, the CCD 12 is driven to scan, and an analog photoelectric conversion output is sent to the analog signal processing unit 13. .
[0017]
In this analog signal processing unit 13, the gain is appropriately adjusted for each primary color component of RGB in the state of an analog value signal, and then sampled and held, converted into digital data, and then input to a DSP 14 (Digital Signal Processor). The
[0018]
The DSP 14 executes color process processing including pixel interpolation processing to generate digital value luminance signals Y and color difference signals Cb, Cr, while a focus range space set in advance via a high-pass filter 15 as shown in the figure. Only image data having a high frequency is extracted and output to the integrator 16.
[0019]
The integrator 16 integrates the output value from the high-pass filter 15 to obtain an integrated value of image data with more high-frequency components and high contrast, and the integrated value is sent to the microcomputer 17.
[0020]
As shown in FIG. 4, the microcomputer 17 includes a medium storing a control program, a ROM 17a and a RAM 17b that operates as a work memory, and includes a CPU 17c that operates based on the control program recorded in the ROM 17a. The in-focus state is determined based on the integrated value obtained from 16 and the focus adjustment stepping motor 18 is driven and controlled based on the determination result.
[0021]
The stepping drive of the stepping motor 18 is transmitted to the lens optical system 11 via the link member 19, and the lens optical system 11 is arranged at a position on the optical axis according to the instruction of the microcomputer 17, An image in a desired in-focus state is projected on the CCD 12.
[0022]
Next, the operation of the above embodiment will be described.
[0023]
FIG. 2 exemplifies the operation of automatic focus detection executed by the control of the microcomputer 17. The horizontal axis represents the driving position step of the lens optical system 11 by the stepping motor 18, and the vertical axis represents the lens optical system 11. The integrated value by the integrator 16 of the output of the high-pass filter 15 obtained corresponding to the driving position is shown, and becomes a peak because the contrast is maximized near the focal point.
[0024]
Accordingly, the position where the integral value indicated by I in the figure is the maximum is the in-focus position of the lens optical system 11, and II and III are respectively one step and two steps from the in-focus position to the near side from the subject. It is a so-called “front pin” state that has moved, and here, the positions of II and III deviate from the depth of field of the in-focus position I.
[0025]
Thus, in the operation of the present embodiment, for example, in addition to the in-focus position I as described above, the in-focus positions II and III in front of the subject out of the depth of field, a total of three in-focus states, once. It is assumed that three consecutive pictures are taken by operating the shutter button.
[0026]
FIG. 3 shows a characteristic of an integral value corresponding to the lens driving position shown in FIG. 2 in the process (hereinafter referred to as an evaluation value) in which an automatic focusing operation is performed by half-pressing the shutter button of the camera. ) Is stored in the RAM 17b in the microcomputer 17 until the peak of the integral value is detected (focused), and then the in-focus position I where the shutter button is fully pressed to detect the peak of the integral value. 3 shows the operation after taking and storing one image, and shows the processing contents related to the photographing at the positions II and III out of the in-focus position executed by the microcomputer 17.
[0027]
In this case, the stored position of the lens optical system 11 and the integrated value as the evaluation value are stored in an order that gradually moves away from the in-focus position I toward the subject (camera side). Shall. Further, as shown in FIG. 5, the driving position of the lens optical system 11 and the evaluation value are stored correspondingly.
[0028]
Thus, at the beginning, the number of images (in this embodiment, “2”) that are to be captured (in this embodiment, “2”) is the number of images including the focal point among the evaluation values obtained by the automatic focusing operation. After confirming that the number is smaller than the number stored on the near side (step S01), the value corresponding to the head position II among the evaluation values is larger than a preset value (threshold value), and the lens optical system 11 confirms that the minimum focus state is secured at position 11 (step S04), and confirms that the position of the lens optical system 11 is outside the depth of field (step S05). Then, the lens optical system 11 is moved to the position II outside the depth of field and the image in a state where the depth of field is shifted is captured (step S06).
[0029]
Thereafter, it is determined whether or not all the images have been captured (step S07). If it is determined that the capturing has not ended, the process returns to step S04, and the evaluation value at the position III is set to the set value again in the same manner as described above. (Step S04) and the depth of field is confirmed (step S05), and the lens optical system 11 is moved to the position III outside the depth of field to move the depth of field. An image with a shifted depth is captured (step S06).
[0030]
If it is determined in step S07 that all the images have been captured, the process ends.
[0031]
In step S01, it is determined that the number of images scheduled to be photographed by shifting the focus (in this embodiment, “2”) is larger than the number of evaluation values stored on the near side of the subject including the focal point by the automatic focusing operation. In such a case (for example, when the automatic focusing operation is started from the vicinity of the peak of the integrated value as a result), the lens optical system 11 is again used to obtain the integrated value characteristic as shown in FIG. Moving from the in-focus position I outside the depth of field on the near side of the subject (step S02), a necessary number of evaluation values are newly obtained (step S03), and then the process proceeds to step S04.
[0032]
As described above, since a plurality of images with different in-focus states are continuously photographed by a single shutter key operation, including images that are intentionally out of the depth of field, the operation is simpler. However, it is possible to increase the possibility of obtaining a still image in a desired in-focus state.
[0033]
In the above embodiment, the in-focus position and the position where the focus is shifted from the in-focus position to the near side of the subject are continuously photographed. This is due to the characteristic that the rear side of the subject extends in a larger range than the front side of the subject with respect to the position, and the present invention is not limited to this, and images are taken over a plurality of positions before and after the in-focus position. The number of images taken continuously may not be limited.
[0034]
Further, although the present embodiment has been illustrated for the case where it is applied to a digital still camera, the present invention can produce the same effect without any problem even if it is a silver salt camera.
[0035]
In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.
[0036]
Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, at least one of the problems described in the column of the problem to be solved by the invention can be solved, and described in the column of the effect of the invention. In a case where at least one of the obtained effects can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.
[0037]
【The invention's effect】
According to the present invention , since a plurality of images with different in-focus states are continuously photographed by a single shutter key operation, a still image in a desired in-focus state can be obtained with a simpler operation. Can increase the sex.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an image pickup system of a digital still camera according to an embodiment of the present invention.
FIG. 2 is a diagram showing a relationship between a lens driving position and an integral value indicating a focused state according to the embodiment.
FIG. 3 is a flowchart showing processing details of continuous shooting executed after capturing an image in a focused state according to the embodiment;
FIG. 4 is an exemplary block diagram showing an internal circuit configuration of the microcomputer according to the embodiment;
FIG. 5 is a view showing a correspondence between a driving position of the lens optical system according to the embodiment and an evaluation value;
[Explanation of symbols]
11 ... Lens optical system 12 ... CCD
13 ... Analog signal processing unit 14 ... DSP
15 ... High pass filter (HPF)
16 ... Integrator 17 ... Microcomputer
18 ... Stepping motor 19 ... Link member

Claims (2)

Detection means for calculating an evaluation value for evaluating the degree of focusing of a light image incident on the image sensor via the optical lens system;
First imaging control means for varying the driving position of the lens optical system to capture an image at the maximum of the evaluation value;
Ri Do the depth of field outside the drive position of the maximum time of the lens optical system of the evaluation value, and the second the evaluation value is to capture an image by driving the lens optical system to a position equal to or higher than a predetermined value Imaging control means ,
An imaging apparatus characterized in that imaging is performed by the first imaging control means and the second imaging control means by a photographer operating a shutter button . A detection step for calculating an evaluation value for evaluating the degree of focusing of a light image incident on the image sensor via the optical lens system;
A first imaging control step for varying the driving position of the lens optical system to capture an image at the maximum of the evaluation value;
Ri Do the depth of field outside the drive position of the maximum time of the lens optical system of the evaluation value, and the second the evaluation value is to capture an image by driving the lens optical system to a position equal to or higher than a predetermined value And an imaging control step.

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