JP2002084446A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device that can suppress generation of an unnatural image due to excessive edge emphasis in an ultra resolution photographing mode and express details of an object. SOLUTION: The image pickup device is provided with a setting value revision means 58 that revises a coring setting value and a contour emphasis gain setting value depending on a mode selected from a usual photographing mode and an ultra resolution photographing mode. Thus, selecting a coring setting value and a gain setting value in the ultra resolution photographing mode smaller than those in the usual photographing mode can avoid an edge from being excessively emphasized and generate a natural image, a detailed image signal is utilized and a delicate mass sense of the object can excellently be expressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an imaging apparatus such as a digital camera having a super-resolution shooting mode in addition to a normal shooting mode.

[0002]

2. Description of the Related Art A digital camera having a super-resolution photographing mode for photographing a plurality of images suitable for generating one super-resolution image from a plurality of photographed images is known.

On the other hand, in a digital camera, the edge of a photographed image tends to be blurred as compared with an actual subject due to the effects of the resolution of a photographing lens, an optical low-pass filter, and the like, and contour enhancement processing is performed to correct this. It is common.

[0004] Specifically, only high-frequency components of an image signal obtained by imaging are extracted and multiplied by a gain,
By combining this with a low frequency component, the edge blur is improved.

Conventionally, an apparatus has been proposed in which the set value of the contour emphasis gain is changed according to the set photographing scene. In a digital copying machine, the edge emphasis amount is changed between a normal mode and a photograph mode. The technology is known.

By the way, in a digital camera, when an image signal is subjected to contour enhancement processing, a gain is also applied to a noise component, so that image deterioration is caused as it is. For this reason, before applying a gain for edge enhancement, it is common to perform a coring process for removing a noise component.

[0007]

However, since the resolution of the above-described super-resolution image is higher than that of the image obtained in the normal shooting mode, it is necessary to set the same contour enhancement gain as in the normal shooting mode. In the contour enhancement process, excessive edge enhancement is performed, and an unnatural image is generated.

In the coring process, if the coring set value is the same as that in the normal photographing mode, not only noise but also a small image signal is deleted, and it becomes difficult for a subtle texture of the subject to appear in the image.

The present invention has been made in view of the above circumstances, and eliminates generation of an unnatural processed image due to excessive edge enhancement of a high-resolution image obtained in a super-resolution photographing mode. It is an object of the present invention to provide an imaging device capable of sufficiently expressing the image.

[0010]

SUMMARY OF THE INVENTION The above object is achieved by an image pickup means, a mode selection means capable of setting a super-resolution photographing mode in addition to a normal photographing mode, and a photographing operation performed by the image pickup means in the super-resolution photographing mode. A high-resolution image generating means for generating one high-resolution image from the plurality of images, and a core for an image taken by the imaging means in the normal mode or the high-resolution image in the super-resolution shooting mode. Coring and contour enhancement processing means for performing coring processing according to a ring setting value, and further performing contour enhancement processing on the image signal subjected to coring processing according to a contour enhancement gain setting value, and according to the shooting mode, The present invention is also achieved by an imaging apparatus comprising: a set value change control unit configured to change each set value.

[0011] According to this imaging apparatus, a coring / contour emphasis processing unit applies a core to an image taken in the normal mode or a high-resolution image generated by the high-resolution image generation unit in the super-resolution imaging mode. Coring processing is performed according to the ring setting value, and contour enhancement processing is performed according to the contour enhancement gain setting value. Therefore, edges in a state where noise is reduced are emphasized. At that time,
The coring set value and the contour emphasis gain set value are changed by the set value change control means in accordance with each mode of the normal shooting and the super-resolution shooting. That is, in the super-resolution shooting mode, if the coring set value and the gain set value are smaller than the respective set values in the normal shooting mode, the edge is not excessively emphasized, and a natural high-resolution image can be obtained. As well as being obtained, a fine image signal, which is information on the details of the image, is also utilized, and the subtle texture of the subject is sufficiently expressed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an external perspective view of a digital camera as an image pickup apparatus according to an embodiment of the present invention, and FIG. 2 is a rear view of the digital camera.

1 and 2, a photographing lens 11, a finder window 14, a distance measuring window 19, and the like are provided on the front surface of a camera body 1A of the digital camera 1.
Inside the camera body 1A, a CCD 12 as an example of an image pickup device that receives an optical image from the photographing lens 11 and performs photoelectric conversion is provided. And the taking lens 1
1. The imaging means includes the CCD 12 and the like.

Further, a release (shutter) button 13 and a shooting condition setting key 17 are provided on the upper surface of the camera body 1A.
And a liquid crystal panel 18 and the like. An insertion port 16 through which the recording medium 15 can be inserted and removed is provided on a side surface of the camera body 1A.

The photographing condition setting key 17 is a liquid crystal panel 18
Is used when setting exposure conditions such as aperture priority and shutter speed priority, switching macro photography, and further setting zoom while looking at the display contents of.

As shown in FIG. 2, a liquid crystal monitor 111 for live view display and an image processing mode setting key 110 are provided on the back of the camera body 1A. With the image processing mode setting key 110, a normal shooting mode and a super-resolution shooting mode can be selected and set.

The digital camera 1 is capable of recording an image captured by the CCD 12 on a recording medium 15 in the same manner as a normal camera.

By the way, in the normal pixel density conversion, a resolution exceeding the resolution of the original image cannot be obtained, but in the super-resolution shooting mode, a high-resolution image exceeding the resolution of the original image can be obtained. Specific examples of the high-resolution image generation processing include, for example, an image shifting method disclosed in JP-A-6-225317 and JP-A-7-120665, and a GP repetition method.

FIG. 3 is a block diagram showing an electrical configuration of the digital camera 1, wherein a thin arrow indicates a flow of control data, and a thick arrow indicates a flow of image data.

In FIG. 3, the CCD 12 is set so as to be able to be slightly displaced in the optical axis direction, and is driven and displaced by the CCD position control unit 54 at the time of the second or subsequent photographing in the super-resolution photographing mode. CCD position controller 54
Is composed of, for example, a piezoelectric element.

The A / D converter 51 converts an analog image signal from the CCD 12 into a digital image signal, and the RAM 52 temporarily stores image data.

The high-resolution image generation unit 53 is obtained by turning off the processing in the normal shooting mode, and turning on the processing in the super-resolution shooting mode, and slightly displacing the position of the CCD 12 for each shooting. Processing a plurality of image data to generate a high-resolution image.

The coring and contour enhancement processing section 57
The image signal is subjected to a coring process in accordance with a coring setting value, and the coring-processed image signal is subjected to a contour emphasis process in accordance with a contour emphasis gain setting value.

The coring and contour emphasis setting value switching section 58 is operated by the CPU 50 to change the coring setting value and the contour emphasis gain setting value in accordance with the selected one of the normal photographing mode and the super-resolution photographing mode. Is to switch. In this embodiment, in the super-resolution shooting mode, the coring setting value and the contour enhancement gain setting value are switched so as to be smaller than the respective setting values in the normal shooting mode, for example, as shown in Table 2 in FIG. .

The recording medium 15 stores the image data read from the RAM 52 in the normal photographing mode, and stores the image data generated by the high-resolution image generating section 53 in the super-resolution photographing mode.

The CPU 50 controls the digital camera 1 as a whole. For example, in addition to storing shooting conditions when the release button 13 is pressed, the setting state of the image processing mode setting key 110, and the like, the shooting lens driving unit 36 is controlled based on the distance measurement result in the distance measurement window 19. Control.

Here, the coring process and the contour enhancement process will be described with reference to FIGS.

The contour emphasis process is a process performed to improve the lack of edge feeling due to low resolution.
Specifically, the image signal obtained by imaging is divided into a low frequency component and a high frequency component, and only the high frequency component is extracted,
This is a process of multiplying this by a gain and combining it with a low frequency component.

However, in this contour emphasis processing, a gain is also applied to the noise component, which causes image deterioration. Therefore, coring processing is performed on the image signal before applying the gain.

In this coring process, if the absolute value of the high-frequency component is equal to or less than a certain value X, the signal is regarded as a noise component and its signal is set to zero. Assuming that a noise component of X is present, only X is subtracted from the signal. By doing this,
The noise component can be reduced, and even if a gain for edge enhancement is applied thereafter, image degradation due to noise can be suppressed.

The coring process and the outline emphasis process will be described with reference to FIG. As shown in FIG.
In the coring and contour enhancement processing unit 57, a low-frequency component is extracted from the image signal obtained by the imaging by a low-pass filter (3 × 3) 71 which is a two-dimensional filter for contour enhancement. Then, the low frequency component is subtracted from the original image signal by the adder 72, and only the high frequency component is sent to the coring processing unit 73.

The coring processing section 73 performs processing of setting the outputs of the set values -x to x to "0" assuming that the output is the noise component in the high frequency component. Outputs smaller than the set value -x and larger than the set value x are corrected to a value obtained by subtracting x from the assumption that a noise component is present. It is desirable that the set value x substantially coincides with the noise level.
Noise components can be reduced.

The high-frequency component from which the noise component has been reduced by the coring processing unit 73 is subjected to a multiplier 74 to emphasize the contour.
For example, a constant gain is applied in accordance with the set values shown in Table 1 of FIG. 5, and high-frequency component enhancement processing is performed. The emphasized high-frequency component is added to the low-frequency component by the adder 75 to generate a contour-enhanced image signal in which noise component enhancement is suppressed. For reference, FIG. 6 shows functions before and after the coring and contour enhancement processing at this time.

FIG. 7 is a block diagram showing the coring and contour emphasis processing section 57 applied in this embodiment.

The coring and contour enhancement processing section 57
Low-pass filter (5 × 5) 71A, adder 72A, coring processor 73A, multiplier 74A, and adder 75
A high-frequency component emphasis means 70A comprising a low-pass filter (3 × 3) 71, an adder 72, a coring processing unit 73, a multiplier 74, and an adder 75 similar to FIG. 70 are connected in series.

The coring and contour emphasis processing section 57
Examples of coring value and gain setting value in
The contents shown in Table 2 of FIG. 8 are adopted. In the normal photographing mode, the set value of the parameter pattern 1 is designated, and in the super image photographing mode, the set value of the parameter pattern 2 is designated. As can be seen from Table 2, in the super-resolution shooting mode, the coring set value and the contour enhancement gain set value are set smaller than the respective set values in the normal shooting mode.

Next, a photographing sequence by the digital camera 1 having the above configuration will be described with reference to flowcharts shown in FIGS. Steps are abbreviated as “S”.

Prior to photographing, the user uses the photographing mode setting key 17 and the liquid crystal panel 18 to set exposure conditions such as aperture priority and shutter speed priority and to set white balance mode switching. Further, the user operates the image processing mode setting key 1 while watching the liquid crystal monitor 111.
10 is operated to select the normal shooting mode or the super-resolution shooting mode.

In FIG. 9, in S101, the CPU 50
Determines whether or not the release button 13 has been pressed, and if the release button 13 has been pressed (the determination in S101 is YE
In steps S) and S102, the CPU 50 reads the photographing conditions and image processing mode settings at that time. If the release button 13 is not pressed (NO in S101), the process waits until the release button 13 is pressed. Thereafter, distance measurement is performed in S103.

In S104, the CPU 50 determines whether or not the super-resolution shooting mode is OFF. If the super-resolution shooting mode is set to OFF, that is, if the normal shooting mode is set (YES in S104). YES), S105
Then, the CPU 50 instructs the coring and contour emphasis setting value switching unit 58 to adopt the setting values of the parameter pattern 1 in Table 2 in FIG. 8 for normal shooting, and performs normal shooting.

That is, in step S106, the CPU 50 drives the photographing lens 11 through the photographing lens driving unit 56 so as to focus on the subject.
Integrates (exposes) the CCD 12 for the integration time calculated by
At 108, the image signal is read as data.

In S109, the read image signal is A
Is converted into digital image data by the / D converter 51,
In S110, the digital image data is temporarily stored in the RAM 52. Then, in S111, the CPU 50 sets the high-resolution image generation unit 53 to OFF (no processing), and
At 112, the image data is read from the RAM 52, and the coring and the contour emphasis processing section 57
After performing image processing on the image data in accordance with the coring set value and the gain set value of the parameter 1, S113
Then, the data is recorded on the medium 15.

On the other hand, if the super-resolution shooting mode is set to ON in S104 (the determination in S104 is N
O), super-resolution shooting is performed, and the process proceeds to S201 in FIG.

In FIG. 10, in S201, the CPU 5
0 is the coring and contour enhancement set value switching unit 5
8 to adopt the set value of the parameter pattern 2 in Table 2 of FIG. 8 for super-resolution imaging, and perform super-resolution imaging.

That is, in step S202, the CPU 50 drives the photographing lens 11 through the photographing lens driving unit 56 so as to focus on the subject. In step S203, the CPU 50 integrates the CCD 12 with the integration time calculated by the CPU 50. Reads the image signal as the first image data.

In S205, the read image data is A
Is converted into digital image data by the / D converter 51,
In S206, the digital image data is temporarily stored in the RAM 52.

Next, in S207, the CPU 50 sets the CC
The position of the CCD 12 is displaced by a predetermined amount via the D position control unit 54, and it is determined whether or not the position of the CCD 12 is displaced by a predetermined amount.
The determination at 207 is YES), and the process proceeds to S208. If it has not been displaced by the predetermined amount (NO in S207), it waits until it is displaced.

In S208, the CPU 50 determines whether or not a plurality of images have been shot. If a plurality of images have not been shot (NO in S208), the process returns to S202, and the second shooting is performed as described above. If a plurality of (two) images have been captured (the determination in S208 is YES), in S209, these two image data are read from the RAM 52, and
At 0, the high-resolution image generation unit 53 is turned on to generate one super-resolution image from two images.

Next, in S211, the coring and contour enhancement processing section 57 performs image processing on the super-resolution image data in accordance with the coring set value and the gain set value of the parameter 2, and then records it on the medium 15. .

As described above, in the super-resolution photographing mode, the coring setting value and the contour enhancement gain setting value are smaller than the respective setting values in the normal photographing mode. Generation can be avoided. Furthermore, since the detailed information of the image is utilized even after the coring process, the texture of the subject such as the crushing feeling of tangerine skin and the fluffing feeling of kiwi skin is sufficiently expressed.

The coring and contour enhancement processing unit 5
7 is not limited to that of FIG. 7, but as shown in FIG.
A medium frequency component emphasizing means 70A having a low-pass filter (5 × 5) 71A;
And a selector 61,
In the normal imaging mode, the high-frequency component enhancement means 70 having a low-pass filter (3 × 3) 71 is used for processing, and in the super-resolution imaging mode, a low-pass filter (5 × 5) 71A is provided. Medium frequency component emphasis means 7
The configuration may be such that the selectors 61 and 62 are controlled so as to perform processing at 0A.

That is, in general, the main purpose of image processing in the normal photographing mode is to increase the resolution. Therefore, it is preferable to emphasize high-frequency components.
× 3) High frequency component emphasizing means 70 having 71 is used. On the other hand, in the image processing in the super-resolution shooting mode, a sufficient resolution can be obtained. Therefore, it is more effective to enhance the contrast by emphasizing the middle frequency component than to enhance the high frequency component. And means for enhancing the medium frequency component 7 having a low-pass filter (5 × 5) 71A
0A is used.

Table 3 in FIG. 12 shows examples of coring setting values and contour emphasis gain setting values in the coring and contour emphasis processing section 57 shown in FIG. In the normal shooting mode, the set value of the parameter pattern 3 is specified.
In the super image capturing mode, the set value of the parameter pattern 4 is specified.

The coring setting value and the contour emphasis gain setting value in the coring and contour emphasis processing section 57 shown in FIG.
4, the same effect as described above is exhibited.

In the above-described embodiment, the shift photographing method has been described as a method of photographing a super image. However, another method may be used.

[0057]

As described above, according to the present invention, the coring set value and the contour enhancement gain set value can be changed according to the selected mode of the normal shooting and the super-resolution shooting mode. If the coring set value and the gain set value in the image shooting mode are smaller than the respective set values in the normal shooting mode, the edges are not excessively emphasized, and a natural image can be generated, and a fine image signal is also generated. It can make good use of the subtle texture of the subject.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a digital camera according to an embodiment of the present invention.

FIG. 2 is a rear view showing the same digital camera.

FIG. 3 is a block diagram showing an electrical configuration of the digital camera.

FIG. 4 is a basic configuration diagram of coring and contour enhancement processing means.

FIG. 5 is a table showing an example of a coring set value and an outline emphasis gain set value applied to the configuration in FIG. 4;

FIG. 6 is an explanatory diagram of functions before and after coring and contour enhancement processing.

FIG. 7 is a configuration diagram of coring and contour enhancement processing means applied to this embodiment.

8 is a table showing an example of a coring setting value and an outline emphasis gain setting value applied to the configuration of FIG. 7;

FIG. 9 is a flowchart showing a shooting sequence of the digital camera.

FIG. 10 is a flowchart showing a process in a super image shooting mode.

FIG. 11 is a configuration diagram showing another example of coring and contour enhancement processing means.

12 is a table showing an example of a coring set value and an outline emphasis gain set value applied to the configuration of FIG. 11;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Digital camera (imaging device) 11 ... Photographing lens 12 ... Image sensor 58 ... Coring and contour emphasis setting value switching part (setting value changing means) 57 ... Coring and contour Emphasis processing section 70: High-frequency component emphasis means 70A: Medium-frequency component emphasis means 110: Image processing mode setting key (mode selection means)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Shinichi Fujii, Inventor Shinichi Fujii 2-3-1-13 Azuchicho, Chuo-ku, Osaka City, Osaka International Building Minolta Co., Ltd. F-term (reference) 2H054 AA01 5C021 PA12 PA16 PA17 PA34 PA66 RB00 XB03 YC08 ZA02 5C022 AA13 AB00 AC01 AC69

Claims (1)

[Claims] 1. An image pickup means, a mode selection means capable of setting a super-resolution photographing mode in addition to a normal photographing mode, and one image from a plurality of images photographed by the image pickup means in the super-resolution photographing mode. High-resolution image generating means for generating a high-resolution image, and coring processing according to a coring setting value for an image taken by the imaging means in the normal mode or the high-resolution image in super-resolution shooting mode. And coring / contour enhancement processing means for performing contour enhancement processing on the image signal subjected to the coring processing according to the contour enhancement gain setting value, and setting values for changing each of the setting values according to the shooting mode An imaging device, comprising: changing means.