JP2001054014A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electronic camera that automatically adjusts a gradation expression of image data in matching with diversified objects by providing a split photometric sensor, which divides the object into a plurality of areas and senses them, to the electronic camera and changing a gradation conversion characteristic in response to a split photometric result of the split photometric sensor. SOLUTION: A split photometric sensor 15 consists of a photometric element where a plurality of photoelectric conversion elements with sensitivity in RGB colors is arranged in a matrix, divides an object into a plurality of areas and applies photometric processing to them. The electronic camera is provided with a microprocessor 27. The microprocessor 27 instructs a gradation conversion section 25 to change its characteristic to a soft gradation curve and instructs a color difference arithmetic section 26 to change its characteristic to a soft gradation use color conversion matrix. Thus, the electronic camera properly and automatically adjusts its gradation conversion characteristic and its color conversion characteristic in response to a split photometric result. Thus, the electronic camera can obtain image data in an excellent gradation expression at all times in preparation for diversified photographing states.

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 changing gradation conversion characteristics of image data based on the result of divided photometry.

[0002]

2. Description of the Related Art Conventionally, in an electronic camera, γ correction or the like has been performed on captured image data for the purpose of correcting the gradation characteristics inherent to an image pickup device or matching the nonlinear gradation display characteristics of a monitor device. Has been implemented.

[0003]

In a conventional electronic camera, when a subject having a large difference in luminance exists in a screen, blackouts and overexposures are liable to occur in an image pickup device, and a minute gradation change is insufficient. The problem of seeing was easy to occur. Conversely, when the luminance difference in the screen is extremely small, the entire screen is no longer sharp, and a problem that the image looks sleepy is likely to occur.

Therefore, in the inventions according to claims 1 to 7,
An object of the present invention is to provide an electronic camera that automatically adjusts gradation expression of image data according to various subjects. It is another object of the present invention to provide an electronic camera that automatically adjusts color information of an image in accordance with a change in gradation conversion characteristics.

[0005]

An embodiment (FIG. 1, FIG. 1)
Means for solving the problem will be described while associating the reference numerals in FIG. 2). Note that the association here is for reference and does not limit the present invention.

According to the first aspect of the present invention, an imaging means (13) for imaging a subject and generating image data.
And a gradation conversion unit (25, 27) for converting the gradation of image data generated by the imaging unit into a plurality of regions. 15), wherein the gradation conversion means changes the characteristic of the gradation conversion according to the divided photometry result of the divided photometry sensor.

In the above configuration, the gradation conversion characteristic of the image data is changed in association with the result of the divided photometry. Usually, from the results of this type of split metering, the contrast in the screen,
It is possible to obtain abundant subject information such as a luminance distribution state in a screen, a backlight / direct light distribution state, and an area of an improper exposure area. Therefore, in the present invention, it is possible to finely optimize the gradation conversion characteristics of image data by utilizing such abundant subject information.

<Second Aspect> According to a second aspect of the present invention, there is provided the electronic camera according to the first aspect, wherein the gradation conversion means (2
5, 27) has means (27) for determining the in-screen contrast based on the divided photometry results. If it is determined that the in-screen contrast is weak and the visual gradation change is poor, the gradation conversion is performed. Change the characteristic to “direction to emphasize gradation change”. Conversely, if it is determined that the contrast in the screen is too strong and the visual gradation change is poor, change the gradation conversion characteristic to “ In the direction of weakening ”.

In the above configuration, the gradation converting means includes:
If it is determined from the result of the divided photometry that the in-screen contrast is weak, the gradation conversion characteristic is changed in a direction to emphasize the gradation change. As a result, the gradation expression of the image data is rich and undulating, and the details of the image are more clearly expressed, so that more beautiful image data can be obtained. On the other hand, when the gradation conversion means determines that the in-screen contrast is high based on the result of the divided photometry, the gradation conversion characteristic is changed in a direction to reduce the gradation change. In this case, a fine gradation component which is hardly seen visually on the white level side or the black level side slightly moves toward the intermediate gradation. As a result, these hardly visible gradation components appear clearly, and beautiful image data with delicate gradation expression can be obtained.

According to a third aspect of the present invention, in the electronic camera according to the first or second aspect, the gradation conversion means (25, 27) includes a divided photometric sensor (15).
The highest luminance value Bvmax, the lowest luminance value Bvmin, the luminance difference dBv between the highest luminance value and the lowest luminance value, the luminance value (control luminance value Bvamp) and the luminance value of the divided area, the luminance distribution in the screen, the luminance difference between the top and bottom of the screen, and the scene discrimination. At least one data is obtained, and gradation conversion is performed according to the obtained data. The characteristic is changed.

All of the above-listed data are data obtained from the results of the divided photometry and are particularly effective data for classifying the characteristics of the subject. Therefore,
By using any one of such data, it is possible to perform an operation of changing the gradation conversion characteristic that accurately reflects the characteristics of the subject.

According to a fourth aspect of the present invention, in the electronic camera according to any one of the first to third aspects, the gradation conversion means (25, 27) is provided with an image pickup means. Brightness value used as a reference for exposure setting (control brightness value Bvamp)
It is determined whether or not the luminance difference between the luminance value and the luminance value of each divided region falls within a predetermined range. If the luminance difference falls within the predetermined range, it is determined that the entire screen is in soft contrast, and the characteristic of the gradation conversion is determined. Is changed to “a direction in which a gradation change is emphasized”.

Normally, the split metering is performed in the state of the open aperture.
This is performed in a state different from the exposure condition at the time of imaging. In many cases, the exposure setting of the imaging unit is intentionally shifted due to manual exposure setting, exposure correction, or the like. Therefore, in the above configuration, the brightness value of each divided region is relatively shifted by the control brightness value Bvamp, and it is determined whether or not the relative brightness difference falls within a predetermined range, thereby determining the soft contrast. I do. In order to determine such a soft contrast, the above configuration changes the tone conversion characteristic in a direction that emphasizes the tone change. Therefore, the gradation change in the middle range is appropriately emphasized, and clear and beautiful image data rich in gradation change can be obtained.

According to a fifth aspect of the present invention, in the electronic camera according to any one of the first to fourth aspects, the gradation conversion means (25, 27) is arranged so that: The value Bvmax does not saturate in the exposure setting of the imaging means. "
Also, it is determined whether or not a condition of “the brightness difference between the highest brightness value Bvmax and the control brightness value Bvamp exceeds the first threshold value” is satisfied. If the condition is satisfied, a part of the image having the gradation information is determined. It is characterized in that it is determined that there is a tendency for overexposure, and the characteristic of the gradation conversion is changed to "a direction in which the gradation change is weakened".

In the above configuration, the following two conditions are determined. The maximum luminance value Bvmax is not saturated in the exposure setting of the imaging means. The luminance difference between the maximum luminance value Bvmax and the control luminance value Bvamp exceeds the first threshold. When these conditions are satisfied, a part of the image is
It can be determined that there is a tendency for overexposure while having gradation information. With respect to such a determination, the above-described configuration changes the gradation conversion characteristic in a direction in which the gradation change is weakened. At this time, the fine gradation component which has a tendency to overexpose and is hardly visually recognized slightly moves toward the intermediate gradation. As a result, the gradation expression of the entire screen becomes visually rich, and beautiful image data with delicate description can be obtained.

According to a sixth aspect of the present invention, in the electronic camera according to any one of the first to fifth aspects, the gradation conversion means (25, 27) includes a maximum brightness value. The luminance difference dBv between Bvmax and the minimum luminance value Bvmin is the second.
It is determined whether or not the threshold value is exceeded, and if it is greater than the second threshold value, it is determined that a high-luminance object (the sun, a lighting fixture, a highlight, etc.) is located in the screen, and the change in the characteristics of the gradation conversion is stopped. It is characterized by doing.

In general, when a high-luminance object is positioned in a screen, if it is simply determined that the contrast is high and the gradation change is weakened, the gradation expression of the main subject is greatly impaired. Therefore, in the above configuration, the luminance difference dBv
If the value is larger than the threshold value, the change in the characteristics of the gradation conversion is suppressed. As a result, it is possible to reliably avoid problems such as loss of gradation expression of the main subject.

<Seventh Aspect> According to a seventh aspect of the present invention, there is provided an image capturing means for capturing an image of a subject and generating image data, and a tone converting means for performing tone conversion on the image data generated by the image capturing means. In the electronic camera provided with the image processing device, in the monochrome photographing mode, the gradation conversion means (25, 27) changes the characteristic of the gradation conversion to “the direction to make the image brighter” to clarify the fine gradation change. It is characterized by the following.

As a general tendency, in monochrome photography,
It is preferable to describe a fine gradation change as clearly as possible. Therefore, in the above configuration, in the case of the monochrome photographing mode, the characteristic of the gradation conversion is changed to “the direction to make the image brighter”. As a result, portions that are dark and flat are raised by the amount that there is no color change, and it is possible to obtain clear and beautiful monochrome image data of dark and light (fine gradation change).

<Eighth Aspect> According to an eighth aspect of the present invention, an imaging means (15) for imaging an object and generating image data.
And tone conversion means (25,
27) and color conversion means (2) for performing color conversion of image data.
6, 27), wherein the color conversion means changes the color conversion characteristics in response to the change in the characteristics of the gradation conversion by the gradation conversion means.

In the above configuration, it is possible to automatically adjust the characteristics of the color conversion with the change of the characteristics of the gradation conversion.

According to a ninth aspect, in the electronic camera according to the eighth aspect, the color conversion means (2
6, 27) is characterized in that the color conversion characteristic is changed in such a direction as to cancel the hue change of the image data caused by the characteristic change of the gradation conversion means (25, 27).

Ideally, the hue does not change by changing the characteristics of the gradation conversion. However, depending on the color temperature setting of the display monitor, etc., due to the change in the characteristics of gradation conversion,
It is expected that a slight hue shift will occur. Assuming such a situation, in the above configuration, the color conversion characteristic is changed in a direction to cancel the hue change caused by the change in the characteristic of the gradation conversion. As a result, it is possible to correct the hue shift and obtain accurate hue image data.

According to a tenth aspect of the present invention, in the electronic camera according to the eighth or ninth aspect, the color conversion means (26, 27) includes the gradation conversion means (2
The color conversion characteristics are changed in such a direction as to correct the change in the color tone of the image data caused by the characteristic change of (5, 27).

It is expected that the color of the image data will become lighter or darker due to the change in the characteristics of the gradation conversion. Assuming such a situation, in the above-described configuration, the color conversion characteristic (particularly, saturation) is changed in a direction to correct the color tone change of the image data caused by the change in the characteristic of the gradation conversion. As a result, the color density of the image data does not change drastically, and image data having a natural color tone can be obtained.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is described in claims 1 to 1.
0 is an embodiment corresponding to the invention described in FIG.

<< Structure of Embodiment >> FIG. 1 is a view showing a schematic structure of an electronic camera 11 according to the present embodiment. FIG.
As shown in FIG. 1, a photographing lens 12 is attached to the electronic camera 11. An image sensor 13 is disposed on the image space side of the photographing lens 12 via a mirror box 12a.
A finder optical system 14 is arranged in the reflection direction of the mirror box 12a. Part of the finder optical system 14 is provided with a split photometric sensor 15. The split photometric sensor 15 here is composed of a photometric element in which a plurality of photoelectric conversion elements each having sensitivity to RGB are arranged in a matrix, and divides a subject field into a plurality of regions to perform photometry.

FIG. 2 is a block diagram showing a signal processing system of the electronic camera 11. In FIG. 2, image data captured by the image sensor 13 is linearly quantized by an A / D conversion circuit 21 and is digitally converted into image data of 12 bits for each of RGB. The digitally converted image data is sequentially processed through a clamp processing unit 22 that performs a clamp process, a white balance adjustment unit 23 that performs a white balance adjustment, and a black level correction unit 24 that performs a black level correction. It is input to the tone conversion unit 25 and the color difference calculation unit 26.

In the gradation conversion section 25, each of the RGB colors 12
Performs gradation conversion on image data of bits, and outputs RGB
Outputs 8-bit image data for each color. The color difference calculating section 26 multiplies the 8-bit image data of each of the RGB colors by a color conversion matrix to convert the image data into luminance Y, color difference Cb, and Cr. The luminance / color difference data YCbCr thus processed
Are recorded on a memory card or the like after undergoing image compression processing such as JPEG compression. On the other hand, in the electronic camera 11,
A microprocessor 27 for system control is provided. The microprocessor 27 performs the operation setting of the gradation conversion unit 25 and the color difference calculation unit 26 prior to the signal processing of the image data.

<< Operation of Embodiment >> FIG. 3 is a diagram for explaining an operation setting routine of the gradation conversion unit 25 and the color difference calculation unit 26, which is executed by the microprocessor 27. FIG. 4 is a diagram showing four types of gradation curves set by the microprocessor 27. Each of these gradation curves is in the form of table data or the like.
It is stored in the gradation conversion unit 25 in advance. FIG. 5 is a diagram showing the inclinations (corresponding to gradation changes) of the three types of gradation curves in comparison with the inclinations of the standard gradation curves. Hereinafter, the operation of this embodiment will be described along the operation steps shown in FIG.

[Step S1] First, the microprocessor 27 determines whether or not the electronic camera 11 is set to the monochrome photographing mode. Here, if the monochrome shooting mode has been set, the microprocessor 27 shifts the operation to Step S4. On the other hand, if the monochrome shooting mode has not been set, the microprocessor 27 shifts the operation to step S5.

[Step S2] Microprocessor 27
Instructs the gradation conversion unit 25 to change the characteristic to a monochrome gradation curve. The microprocessor 27
Instructs the color difference calculation unit 26 to change the characteristics to the monochrome gradation color conversion matrix. After such an instruction,
The microprocessor 27 ends the operation setting routine. The two characteristics indicated here have the following characteristics.モ ノ ク ロ Monochrome gradation curve: This characteristic raises the gradation from the black side to the middle range and makes the image brighter than the standard gradation curve (see FIG. 4). As a result of such gradation conversion, the entire image becomes visually bright. As a result, the difference in the color tone of the subject, which tends to be buried in the shaded area, is clearly expressed as a subtle shade (gradation difference), and beautiful monochrome image data can be obtained. ◎ Color conversion matrix for monochrome gradation: Here, the conversion coefficient of luminance Y is subjectively adjusted so that the color tone and color density of the color image are converted beautifully as the density of luminance Y. .

[Step S3] Microprocessor 27
Acquires the divided photometry result from the divided photometry sensor 15 at the time of imaging of the image data to be processed.

[Step S4] Microprocessor 27
Determines whether or not the following conditional expressions (1) and (2) are satisfied. | Highest luminance value Bvmax-Control luminance value Bvamp | ≦ H1 (1) | Lowest luminance value Bvmin−Control luminance value Bvamp | ≦ H2 (2) In the above equation, the control luminance value Bvamp is the electronic camera 11 Is a luminance value used as a reference for the exposure setting. For example, A
In the E photography, the control brightness value Bvamp is calculated from the divided photometry results according to the calculation conditions for multi-pattern photometry. Further, the maximum luminance value Bvmax corresponds to the maximum value among the luminance values of each divided area. The minimum luminance value Bvmin corresponds to the minimum value among the luminance values of each divided area. Further, H1, H2
Is a boundary value that determines an upper limit and a lower limit for determining whether or not the contrast is soft, and is set to, for example, a value of about Bv 0.5.

When both of the above conditional expressions (1) and (2) are satisfied, (luminance value of each divided area−control luminance value Bvamp) falls within a predetermined range (−H2 to H1). Can be determined to be soft contrast. In this case, the microprocessor 27 shifts the operation to Step S7. On the other hand, when either of the conditional expressions (1) and (2) is not satisfied, the microprocessor 27 shifts the operation to Step S8.

[Step S5] Microprocessor 27
Instructs the gradation conversion unit 25 to change the characteristic to a high gradation curve. Similarly, the microprocessor 27
The color difference calculation unit 26 is instructed to change the characteristics to the color conversion matrix for high contrast gradation. After such an instruction, the microprocessor 27 ends the operation setting routine. The two characteristics indicated here have the following characteristics.硬 High gradation curve: A characteristic in which gradation change in the middle range is greatly emphasized as compared with the standard gradation curve (see FIG. 5).
As a result of such gradation conversion, inconspicuous gradation changes concentrated in the middle range are enlarged, and clear and beautiful image data rich in gradation changes is obtained. ◎ Color conversion matrix for high contrast gradation: A conversion coefficient for the color difference CbCr which cancels the hue change due to the high gradation curve and corrects the saturation change. Note that, specifically, the subjective evaluation of the image after the color difference conversion is repeated on a trial basis, so that image data having a natural color is obtained.
A conversion coefficient is defined.

[Step S6] Microprocessor 27
Determines whether or not the following conditional expressions (3) and (4) are satisfied. L1 ≦ | maximum luminance value Bvmax−control luminance value Bvamp | ≦ L2 (3) | maximum luminance value Bvmax−minimum luminance value Bvmin | ≦ L3 (4) In the above equation, L1 is the control luminance value In the electronic camera 11 whose exposure is set based on Bvamp, this is a threshold value for determining whether or not the maximum luminance value Bv tends to overexpose, and is set to, for example, a value of about Bv2. Also,
L2 is a threshold value for determining whether or not the maximum luminance value Bv is saturated in the electronic camera 11 whose exposure is set by the control luminance value Bvamp, and is set to, for example, a value of about Bv3. Further, L3 is a threshold for determining whether or not a high-luminance body such as the sun is located in the screen, and is set to a value of, for example, about Bv5.

When both of the above conditional expressions (3) and (4) are satisfied, a part of the image having the gradation information tends to be overexposed, and high brightness such as the sun is displayed on the screen. It can be determined that the object does not exist. In this case, the microprocessor 27 shifts the operation to Step S9. On the other hand, when one of the conditional expressions (3) and (4) is not satisfied,
The microprocessor 27 shifts the operation to step S10.

[Step S7] Microprocessor 27
Instructs the tone conversion unit 25 to change the characteristic to a soft tone curve. Similarly, the microprocessor 27
The color difference calculation unit 26 is instructed to change the characteristics to the color conversion matrix for soft gradation. After such an instruction, the microprocessor 27 ends the operation setting routine. The two characteristics indicated here have the following characteristics.軟 Soft tone curve: A characteristic in which the tone change in the middle range is weaker than the standard tone curve (see FIG. 5). As a result of such tone conversion, tone components that are visually inconspicuous due to the tendency of overexposure shift toward the intermediate tone. At the same time, a gradation component that is visually inconspicuous due to underexposure or the like also moves toward the intermediate gradation. As a result, the gradation expression of the entire screen becomes visually smooth and rich, and beautiful image data with delicate depiction is obtained. A color conversion matrix for soft gradation: a conversion coefficient for the color difference CbCr is determined so as to cancel a hue change due to a soft gradation curve and to correct a change in saturation. Note that, specifically, the subjective evaluation of the image after the color difference conversion is repeated on a trial basis, so that image data having a natural color is obtained.
A conversion coefficient is defined.

[Step S8] Microprocessor 27
Does not instruct the change of characteristics. As a result, the gradation conversion unit 25
Maintains the setting of the standard gradation curve (for example, γ correction curve) as it is. Further, the color difference calculation unit 26 maintains the setting of the standard gradation color conversion matrix as it is. As described above, the electronic camera 11 appropriately and automatically adjusts the gradation conversion characteristics and the color conversion characteristics in accordance with the result of the divided photometry. Therefore, it is possible to always obtain image data with good gradation expression in response to various photographing situations.

<< Effects of Embodiment >> According to the operation described above, in the present embodiment, if it is determined that the in-screen contrast is weak according to the conditional expressions (1) and (2), the gradation conversion is performed in a direction to emphasize the gradation change. Change characteristics. As a result, it is possible to correct soft contrast and obtain beautiful image data.

In this embodiment, when it is determined that the contrast in the screen is high by the conditional expression (3), the gradation conversion characteristic is changed in a direction to reduce the gradation change. As a result, it is possible to correct hard contrast and obtain beautiful image data with delicate depiction. Further, in the present embodiment,
When the conditional expression (4) is not satisfied, it is determined that the high-luminance body is located in the screen, and the change of the characteristic of the gradation conversion is stopped. As a result, it is possible to reliably avoid problems such as loss of gradation expression of the main subject.

Further, in the present embodiment, in the monochrome photographing mode, the characteristic of the gradation conversion is changed to "the direction for brightening the image". As a result, clear and beautiful monochrome image data can be obtained. In this embodiment, the color conversion characteristics are automatically adjusted in accordance with the change in the gradation conversion characteristics. As a result, it is possible to always obtain image data having a natural color tone irrespective of a change in the characteristics of gradation conversion.

<< Supplementary Items of the Embodiment >> In the above-described embodiment, the divided photometric sensor 15 is provided separately from the imaging device 13 (imaging means). However, the present invention is not limited to such a configuration. . For example, the image sensor 13 may be used as a split photometric sensor. In the above-described embodiment, the gradation curve and the color conversion matrix are selected according to the flowchart shown in FIG. 3, but the present invention is not limited to this. For example, a table as shown in FIG. 6 may be used. In this case, an appropriate gradation curve and color conversion matrix can be quickly selected by referring to the table based on the divisional photometry result (or shooting mode).

In the above-described embodiment, detailed conditions are determined by combining two or more of the maximum luminance value and the control luminance value. By such a condition determination, it is possible to finely distinguish various subjects and change the gradation conversion characteristics more accurately. However, the present invention is not limited to such condition determination. In general, any device may be used as long as the gradation conversion characteristic is changed according to the result of the divided photometry. For example, from the result of the divided photometry, the “highest brightness value Bv
“max”, “minimum luminance value Bvmin”, “maximum luminance difference in screen dBv”, “luminance difference between control luminance value Bvamp and luminance value of divided area”, “luminance value of divided area”, “average luminance difference” May be obtained, and the gradation conversion characteristic may be changed in accordance with the data.

Further, "luminance distribution in the screen" or "luminance difference between the upper and lower parts of the screen" may be obtained from the results of the divided photometry, and the gradation conversion characteristics may be changed in accordance with the data. From these data, the light distribution state of the subject (backlight / direct light, etc.)
In addition, since it is possible to determine the ratio of the sky occupying the screen and the like, it is possible to select a gradation conversion characteristic suitable for these. Alternatively, the divided photometry results may be classified based on actual measurement data in various photographing scenes to determine a photographing scene, and the gradation conversion characteristics may be changed in accordance with the scene determination. By such an operation, it is possible to select a gradation conversion characteristic suitable for a shooting scene.

In the above-described embodiment, it is determined whether or not a high-luminance object exists in the screen based on the maximum luminance difference dBv. This method is an excellent method that can reliably determine whether or not the maximum luminance difference dBv falls within the gradation expression area of the image sensor, but is not limited thereto. Generally, it is determined whether or not the value of the highest luminance value Bvmax protrudes in the screen. If the value of the maximum luminance value Bvmax protrudes, it is determined that a high-luminance body is present, and a change in the characteristics of gradation conversion is suppressed. do it.

[0048]

As described above, according to the first aspect of the present invention, since the gradation conversion characteristic of image data is changed in association with the divided photometry result, it is possible to correspond to detailed luminance information of a photographic scene. As a result, the gradation expression of the image data can be properly optimized.

According to the second aspect of the present invention, if it is determined from the result of the divided photometry that the in-screen contrast is weak, the gradation conversion characteristic is changed in a direction to emphasize the gradation change, so that a beautiful image rich in gradation expression is provided. Data can be obtained.
On the other hand, if the in-screen contrast is determined to be strong based on the divided photometry results, the gradation conversion characteristics are changed in the direction to reduce the gradation change, so that the gradation expression of the entire screen becomes visually rich and delicate. Beautiful image data can be obtained.

The data enumerated in the third aspect of the present invention are all data obtained from the results of the divided photometry, and are data obtained by extracting the characteristics of the subject. Therefore, by changing the characteristics of the gradation conversion in response to one of such data, it is possible to change the characteristics accurately reflecting the characteristics of the subject.

According to the fourth aspect of the present invention, it is determined whether or not (the luminance value of each divided area−the control luminance value Bvamp) is all within a predetermined range. It is possible to accurately determine whether or not contrast is present. Further, since the gradation conversion characteristic is changed in a direction to emphasize the gradation change in accordance with the soft contrast determination, it is possible to obtain image data rich in gradation change.

According to the fifth aspect of the present invention, it is possible to accurately determine whether or not a portion having a tendency to overexpose exists in the screen while having gradation information. In addition, the tone conversion characteristics are changed in such a way that the tone change is weakened in response to such locations, so that the tone expression on the entire screen is visually rich and delicate image data can be obtained. It becomes possible.

According to the sixth aspect of the present invention, since the change in the characteristics of the gradation conversion is suppressed when the high-luminance body is located in the screen, it is possible to reliably avoid the problem that the gradation expression of the main subject is impaired. It is possible to do.

According to the seventh aspect of the invention, in the case of the monochrome photographing mode, the characteristic of the gradation conversion is changed to "the direction of brightening the image", so that clear monochrome image data can be obtained.

According to the eighth aspect of the present invention, it is possible to automatically adjust the color conversion characteristics in accordance with the change in the gradation conversion characteristics.

According to the ninth aspect of the present invention, it is possible to obtain a correct hue image data by canceling out a hue change caused by a change in characteristics of gradation conversion.

According to the tenth aspect of the present invention, the change in the color tone of the image data caused by the change in the characteristics of the gradation conversion is corrected.
Good image data with a natural color tone can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an electronic camera 11 according to an embodiment.

FIG. 2 is a block diagram showing a signal processing system of the electronic camera 11.

FIG. 3 is a diagram illustrating an operation setting routine executed by a microprocessor 27;

FIG. 4 is a diagram showing a gradation curve.

FIG. 5 is a diagram showing a gradient of a gradation curve (gradation of gradation change).

FIG. 6 is a diagram illustrating an example of a matrix for selecting a gradation curve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Electronic camera 12 Photographing lens 12a Mirror box 13 Image sensor 14 Finder optical system 15 Split photometric sensor 21 A / D conversion circuit 24 Black level correction unit 25 Gradation conversion unit 26 Color difference calculation unit 27 Microprocessor

Claims (10)

[Claims] 1. An electronic camera comprising: an imaging unit configured to image a subject to generate image data; and a gradation conversion unit configured to perform gradation conversion on the image data generated by the imaging unit. An electronic camera, comprising: a divided photometric sensor that divides the photometric data into a plurality of regions, and performs photometry, wherein the gradation conversion unit changes a characteristic of the gradation conversion according to a divided photometry result of the divided photometry sensor. . 2. The electronic camera according to claim 1, wherein said gradation conversion means has means for determining an in-screen contrast based on said divided photometry result, and said in-screen contrast is weak and visual. If it is determined that the gradation change is poor, the gradation conversion characteristic is changed to “a direction in which the gradation change is emphasized”. Conversely, if the contrast in the screen is too strong and the visual gradation change is poor, An electronic camera characterized in that when it is determined, the tone conversion characteristic is changed to "a direction in which tone change is weakened". 3. The electronic camera according to claim 1, wherein the gradation conversion unit is configured to: (a) a maximum luminance value Bvmax; (b) a minimum luminance value Bvmin; A brightness difference dBv between the highest brightness value and the lowest brightness value; a brightness difference between a brightness value (control brightness value Bvamp) used as a reference for the exposure setting of the imaging means and a brightness value of the divided area; An electronic camera characterized in that at least one of the following: distribution, luminance difference between the top and bottom of a screen, and scene determination is obtained, and the gradation conversion characteristic is changed in accordance with the data. 4. The electronic camera according to claim 1, wherein the gradation conversion unit includes a luminance value (control luminance value Bvamp) as a reference for setting an exposure of the imaging unit. It is determined whether or not the luminance difference from the luminance value of each divided region falls within a predetermined range. If the luminance difference falls within the predetermined range, it is determined that the entire screen has a soft contrast, and the gradation conversion characteristic is determined. An electronic camera characterized in that the direction is changed to "direction to emphasize gradation change". 5. The electronic camera according to claim 1, wherein the gradation conversion means includes: “the highest luminance value Bvmax is not saturated in the exposure setting of the imaging means”; Maximum brightness value Bvmax and control brightness value B
whether the luminance difference from vamp exceeds the first threshold ”is satisfied, and if the condition is satisfied, it is determined that a part of the image having the gradation information has a tendency to overexpose. An electronic camera characterized in that the characteristics of gradation conversion are changed to "directions in which gradation change is weakened". 6. The electronic camera according to claim 1, wherein said gradation conversion means includes a luminance difference dB between a maximum luminance value Bvmax and a minimum luminance value Bvmin.
It is determined whether or not v is greater than a second threshold. If the value of v is greater than the second threshold, it is determined that the high-luminance body is located in the screen, and the characteristic change of the gradation conversion is stopped. Electronic camera. 7. An electronic camera, comprising: an imaging unit configured to image a subject to generate image data; and a gradation conversion unit configured to perform gradation conversion on the image data generated by the imaging unit. An electronic camera characterized in that, in a monochrome photographing mode, a characteristic of gradation conversion is changed to "a direction for brightening an image" to sharpen a minute gradation change. 8. An image pickup means for picking up an image of a subject to generate image data, a gradation conversion means for performing gradation conversion of the image data, and a color conversion means for performing color conversion of the image data. In the electronic camera, the color conversion unit changes a color conversion characteristic in response to a change in a gradation conversion characteristic by the gradation conversion unit. 9. The electronic camera according to claim 8, wherein the color conversion unit changes a color conversion characteristic in a direction to cancel a hue change of image data caused by a change in characteristics of the gradation conversion unit. An electronic camera characterized by the following. 10. The electronic camera according to claim 8, wherein the color conversion unit has a color conversion characteristic in a direction to correct a color tone change of the image data caused by a change in the characteristic of the gradation conversion unit. An electronic camera characterized by changing the following.