JPH11341501A - Electrophotographic image pickup device, electrophotographic image pickup method and medium recorded with electrophotographic image pickup control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the image pickup device by which photographing is hardly failed by expressing an object image by means of dot matrix shaped pixels, applying numerical tabulation processing to the image so as to evaluate the image and evaluating photographing conditions based on the evaluation of the image. SOLUTION: The image is expressed by dot matrix shaped pixels. An image pickup means C1 forms the object image on an imaging device or the like via an optical path, the means C1 acquires image data in gradation expression of prescribed element colors, and an image evaluating means numerically analyzes the image data. Since each of individual data is provided on each pixel expressed in a dot matrix, some tabulation processing is conducted for the analysis and the result of tabulation is compared with a prescribed evaluation reference and the comparison result gives an evaluation as to the picked-up image. Then the evaluation result as to the picked-up image is inputted to an image pickup condition evaluation means C3, where the evaluation as to the picked-up image is evaluated again to obtain the evaluation as to the image pickup conditions in the image pickup means C1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic imaging apparatus, an electrophotographic imaging method, and a medium recording an electrophotographic imaging control program.

[0002]

2. Description of the Related Art Conventionally, in this type of electrophotographic imaging apparatus,
Various automatic adjustments are made so that shooting does not fail. For example, an automatic aperture adjustment mechanism that adjusts the aperture according to the brightness of the subject image, an autofocus mechanism that automates focus adjustment, and the like are used.

[0003]

In the above-described conventional electrophotographic imaging apparatus, although various automatic adjustments are performed, it often fails when actually photographed. For example, when a person is captured under backlight conditions,
Since the background is bright, the light amount is reduced by the exposure adjustment, so that the face of a human image, which can be said to be the original subject, appears dark. It was not possible to judge whether it was under backlight conditions because it was only a relative judgment according to the subject.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an electrophotographic imaging apparatus, an electrophotographic imaging method, and a medium in which an electrophotographic imaging control program is recorded, which makes it more difficult for a photographer to fail. With the goal.

[0005]

According to a first aspect of the present invention, an image of a subject is taken via an optical path while setting predetermined photographing conditions, and the subject image is formed in a dot matrix form. Image capturing means for acquiring image data expressed in gradation by a predetermined elemental color which is represented by pixels and color-separated for each pixel, and performs a numerical tabulation process on the acquired image data to a predetermined evaluation criterion. An image evaluation unit that evaluates a captured image based on the evaluation, and a shooting condition evaluation unit that evaluates the shooting condition in the image imaging unit based on the evaluation.

According to the first aspect of the present invention, first, an image of a subject is taken through an optical path while setting predetermined photographing conditions by the image taking means. Then, the image of the subject is represented by dot matrix pixels, and image data is obtained which is expressed in gradation by a predetermined element color which is color-separated for each pixel. Then, the image evaluation means performs a numerical tabulation process on the obtained image data and evaluates the captured image based on a predetermined evaluation criterion. Are evaluated for the above photographing conditions.

That is, an image of a subject is represented by pixels in a dot matrix, the image is evaluated by performing a numerical tabulation process, and photographing conditions are evaluated based on the evaluation. This is different from the evaluation of only the shooting conditions. The image evaluation means evaluates the actually captured image data by performing a numerical tabulation process.
The specific counting process is various and is not particularly limited. The point that image data is once obtained is different from the case where the imaging conditions are simply evaluated. As a preferred example, the invention according to claim 2 is the electrophotographic imaging apparatus according to claim 1, wherein the image evaluation unit extracts a pixel of an object in a subject image based on the image data, and The above-described aggregation process is performed on the image data of the pixels of the object to evaluate the captured image.

[0008] In the invention according to claim 2 configured as described above, the image evaluation means targets only objects in the subject image at the time of numerical totaling processing. That is, the pixels constituting the object are extracted based on the image data, and the tallying process is performed only on the image data of the pixels. It is impossible to discriminate the original subject only by evaluating the shooting conditions as in the past, such as the brightness of the central part of the picture or the average brightness of the whole A desired image can be obtained only under predetermined conditions. However, if the image data is acquired, it is possible to pay attention to the object which is the original subject by various methods, and it is possible to evaluate the image only for the pixels constituting the object.

As an example of determining whether an image is an object, a method of extracting a sharp portion of an image can be adopted. As a photographer's psychology, it is natural to adjust the focus of the subject, and that part naturally becomes a sharp image. In contrast, the background is easily blurred.
Therefore, a sharp part of an image is often an object. In this case, the difference from the conventional case is that the object can be found no matter where it exists.
For example, if the object is often located in the center, it is not different from the evaluation of the conventional shooting conditions,
An object can be found if it is a sharp part whether it is on the left or right of the shooting range.

As an example of the technique, the chromaticity of each pixel can be used. This is because an object can sometimes be specified by a specific color. For example, a person may be judged as a target by searching for a skin color portion. However, it is difficult to specify the skin color in the case of ordinary color image data because it includes a brightness element. On the other hand, the chromaticity represents the absolute ratio of the color stimulus value, and is not affected by the brightness. Therefore, if it is within the range of chromaticity that can be taken for flesh color, it can be determined that the pixel is a person image. Needless to say, the same applies to the range in which trees can take green color and the range in which blue sky takes blue color, in addition to skin color.

On the other hand, the photographing condition evaluation means evaluates the photographing conditions based on the evaluation result of the picked-up image, and the evaluation is to be understood in a broad sense. In other words, it is basically based on notifying the photographer that the photographing conditions are good or bad, but also including reflecting the evaluation result in actual photographing. As a preferred example, the invention according to claim 3 is the electrophotographic image pickup apparatus according to any one of claims 1 and 2, wherein the image pickup means can change the photographing conditions, The imaging condition evaluation means is configured to control the imaging conditions in the image imaging means so that the evaluation based on the captured image is reflected in the imaging conditions.

According to the third aspect of the present invention, since the photographing condition of the image pickup means can be changed, the photographing condition evaluation means is used to reflect the evaluation of the photographed image in the photographing condition. The photographing conditions in the imaging means are controlled. Various specific configurations are possible for such active evaluation. As a preferred example, the invention according to claim 4 is the electrophotographic image pickup apparatus according to claim 3, wherein the image pickup means includes a strobe for illuminating a subject image, and the image evaluation means includes: And the photographing condition evaluating means operates the strobe in the image capturing means when the image evaluating means determines that the object in the subject image is dark.

[0013] In the invention according to claim 4 configured as described above, the image evaluation means evaluates the brightness of the subject image, provided that the image pickup means includes a strobe for illuminating the subject image. When it is determined that the object in the subject image is dark, the photographing condition evaluation means operates the strobe. Therefore, the strobe light is emitted even when the object is still dark, though it is bright overall. Further, as another preferable example, claim 5
According to a third aspect of the present invention, in the electrophotographic imaging apparatus according to any one of the third and fourth aspects, the image capturing unit performs dot formation when a subject image is formed on an imaging surface via the optical path. An image pickup device for performing photoelectric conversion by pixels in a matrix, and an amplifier circuit for amplifying the conversion output of the image pickup device at a predetermined amplification factor, wherein the image evaluation means performs light / dark evaluation in the subject image, The photographing condition evaluation means increases the amplification factor in the amplifier circuit when the image evaluation means determines that the object in the subject image is dark, and decreases the amplification factor when it determines that the object is bright.

[0014] In the invention according to claim 5 configured as described above, when the image pickup means forms an image of the subject on the image pickup surface via the optical system path, it performs photoelectric conversion with pixels in a dot matrix form. The image pickup device includes an image sensor and an amplifier circuit that amplifies the conversion output of the image sensor at a predetermined amplification factor. Therefore, the gradation value output as image data changes depending on the amplification factor in this amplifier circuit. In such a case, the image evaluation means evaluates the brightness of the subject image, and when the object in the subject image is determined to be dark, the photographing condition evaluation means increases the amplification factor in the amplifier circuit. Therefore, even when the image is dark, the gradation value of the image data is output with a large value. Further, when it is determined that the object in the subject image is bright, the photographing condition evaluation means decreases the amplification factor in the amplifier circuit, and even when the object is bright, the gradation value of the image data is output as being small.

In addition, it is naturally possible to involve a mechanical operation in reflecting the photographing conditions. As a preferable example, the invention according to claim 6 is based on any one of claims 3 to 5. In the electrophotographic imaging apparatus according to the aspect, the image capturing unit includes a diaphragm that adjusts a light amount in the optical path, the image evaluation unit performs evaluation of light and dark in the subject image, and the imaging condition evaluation unit includes:
When the image evaluation means determines that the object in the subject image is dark, the aperture is opened, and when it is determined that the object is bright, the aperture is controlled in the direction of decreasing the aperture.

In the invention according to claim 6 configured as described above, when the image pickup means has a stop for adjusting the amount of light in the optical path, the image evaluation means evaluates the brightness of the subject image. When the object in the subject image is determined to be dark, the photographing condition evaluation means controls the direction to open the aperture, and when the object is determined to be bright, the imaging condition evaluation means controls the direction to narrow the aperture. The aperture here is not necessarily limited to a mechanical one. For example, even if the aperture is adjusted for the charging time of the CCD element, it can be said that the aperture is completely equivalent in terms of adjusting the photographing conditions.

Further, as another preferable example involving a mechanical operation, the invention according to claim 7 is the invention according to claims 3 to 6.
In the electrophotographic imaging apparatus according to any one of the above, the image capturing means includes an auto-focus mechanism that automatically adjusts the optical system path so as to focus on a predetermined subject in the subject image, and the image evaluation means includes Evaluating the sharpness of the image in the subject image, and changing the focusing object to an object in the autofocus mechanism when the image evaluating means determines that the subject image is not sharp. There is a configuration to make it.

In the invention according to claim 7 configured as described above, the image pickup means is provided with an auto-focus mechanism for automatically adjusting the optical system path so as to focus on a predetermined subject in the subject image. In case,
The image evaluation means evaluates the sharpness of the image in the subject image, and when it is determined that the subject image is not sharp, the photographing condition evaluation means changes the focused object to an object in the autofocus mechanism.

In the conventional auto-focus mechanism, the object to be focused must be fixed at the center, but since the object is known, the object is adjusted to this object. Further, as another preferable example, the invention according to claim 8 is as follows.
8. The electrophotographic image pickup apparatus according to claim 3, wherein the image pickup means generates a tone value for lightness and darkness for each of a plurality of element colors and can individually adjust output. The image evaluation means evaluates the color balance of the subject image, and the photographing condition evaluation means adjusts the output for each element color when the image evaluation means evaluates the color balance of the subject image as unbalanced. There is a configuration.

In the invention according to claim 8 configured as described above, in the case where the image pickup means generates tone values for light and dark for each of a plurality of element colors and is capable of individually adjusting the output, image evaluation is performed. The means evaluates the color balance of the subject image, and when the color balance of the subject image is evaluated as unbalanced, the shooting condition evaluation means adjusts the output for each element color. In this way, after the subject image is represented by pixels in a dot matrix,
It is easy to understand that a method of evaluating an image by performing a numerical tabulation process and evaluating a photographing condition based on the evaluation is not necessarily limited to a substantial device, and also functions as the method. . For this reason, the invention according to claim 9 captures a subject image via an optical system path while setting a predetermined photographing condition, expresses the subject image by dot matrix pixels, and performs color separation for each pixel. An electrophotographic imaging method for acquiring image data expressed in gradations with element colors of: an image imaging step of imaging a subject image under the imaging conditions to acquire image data; and a numerical value for the acquired image data. Comprising: an image evaluation step of performing a comprehensive aggregation process to evaluate a captured image based on a predetermined evaluation criterion; and a shooting condition evaluation step of evaluating the shooting conditions in the image shooting step based on the evaluation. There is.

That is, there is no difference that the present invention is not necessarily limited to a substantial device but is also effective as a method. By the way, such an electrophotographic imaging device may exist alone, or may be used in a state of being incorporated in a certain device.
It includes various aspects. Therefore, it can be changed as appropriate, such as software or hardware. When the software of the electrophotographic imaging apparatus is used as an example of realizing the idea of the present invention, the software naturally exists on a recording medium on which the software is recorded, and it must be said that the software is used.

As an example thereof, the invention according to claim 10 captures a subject image via an optical path while setting predetermined photographing conditions, and expresses the subject image by pixels in a dot matrix form for each pixel. A medium that stores an electrophotographic imaging control program that is controlled by a computer when acquiring image data expressed by gradation with a predetermined element color that has been color-separated. An image capturing step of acquiring the obtained image data, an image evaluation step of performing a numerical tabulation process on the obtained image data and evaluating a captured image based on a predetermined evaluation criterion, and And a photographing condition evaluation step of evaluating a photographing condition.

Of course, the recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium to be developed in the future. Also, the duplication stages of the primary duplicated product, the secondary duplicated product, and the like are equivalent without any question. In addition, the present invention is not limited to the case where the present invention is used even when the supply is performed using a communication line. further,
The concept of the present invention is not completely different even when part is software and part is realized by hardware, and part is stored on a recording medium and read as needed as needed. Such a form may be adopted.

[0024]

As described above, the present invention provides an electrophotographic imaging apparatus capable of preventing photographing failure by evaluating a photographing condition after photographing a subject image once. Can be. According to the second aspect of the present invention, since the image is evaluated after extracting the original subject, the risk of failure can be further reduced. Furthermore, according to the third aspect of the present invention, since the evaluation result is reflected in the photographing condition, the operability can be improved as compared with the case where the photographing condition has to be adjusted by itself.

Further, according to the invention of claim 4,
The strobe can be automatically emitted even when the subject becomes dark like backlight. Further, according to the invention of claim 5, when the image is dark, the image can be made as bright as possible at the stage of acquiring the image data. Although the image data can be corrected by digital processing in the subsequent process, if the quantization range can be made large at the stage of obtaining the image data, the range of the correction processing will be widened.

Further, according to the invention according to claim 6,
Similarly, when an image is dark, the image can be brightened by a mechanical operation. Further, according to the invention of claim 7, the versatility of focusing is widened even with an autofocus mechanism which tends to be fixed. Furthermore, according to the invention according to claim 8, it is possible to adjust an image which is greatly affected under photographing conditions such as color balance.
Further, according to the ninth aspect of the invention, it is possible to provide an electrophotographic imaging method having the same effect, and according to the tenth aspect of the invention, it is possible to provide a medium in which an electrophotographic imaging control program is recorded. .

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an electrophotographic imaging apparatus according to an embodiment of the present invention in a claim correspondence diagram. In an electrophotographic imaging device that converts a subject image into image data, such as a digital still camera, an image is represented by pixels in a dot matrix, and each pixel represents color and brightness. In order to capture a subject image, the image capturing means C1 is provided with an optical path for setting predetermined photographing conditions. The image capturing means C1 forms a subject image on an image sensor or the like via the optical path, Acquires image data consisting of gradation representations of predetermined element colors,
The image evaluation means C2 numerically analyzes the image data. Since individual data is provided for each pixel in a dot matrix, some sort of tallying processing is performed in the analysis, and the tallying result is compared with a predetermined evaluation criterion to evaluate the captured image. Then, the evaluation result of the captured image is input to the imaging condition evaluation means C3, and based on this evaluation, the image imaging means C1 is re-evaluated so as to evaluate the imaging condition. That is, if the evaluation is that the captured image is dark, an imaging condition that can cause the darkness is derived, and an evaluation that can be good at the time of re-imaging is given.

FIGS. 2 to 5 are block diagrams showing the schematic arrangement of a digital still camera to which the present electrophotographic image pickup apparatus is applied. The controller 10 performs various mechanical and electronic controls, and as shown in FIG. 3, its main components are a CPU 11, a ROM 12, and a RAM 13, which are mutually connected via a bus 14 and It is electrically connected to main external components via the I / O 15. The imaging unit 20 is one of the main components.
Are connected to the controller 10. The imaging unit 20 is shown in more detail in FIG. 4, and includes a distance measuring unit 21 a and an autofocus mechanism 21 b as a part of the optical path 21. In this embodiment, the distance is measured by the distance measuring unit 21a by triangulation or the like, and the autofocus mechanism 21b performs focusing based on the measurement result. In this case, the target of focusing is the center position predicted in advance. Further, the imaging unit 20 includes an imaging device 22 including a CCD device and an AGC circuit 23 that amplifies output data of the imaging device at a predetermined amplification rate.
And an A / D converter 24 for converting an analog output value of the AGC circuit 23 into digital data. These are individually connected to and controlled by the controller 10, and the imaging data is output to the image processing unit 30 as conversion data of the A / D converter 24.

The image processing section 30 is a hardware circuit provided for tuning the characteristics of the optical path 21 and the characteristics of the image pickup device 22. In the case of a single-chip CCD element, red, green, and blue light receiving elements must be arranged in a plane, and individual light receiving elements arranged in two dimensions vertically and horizontally are covered with a red, green, and blue (RGB) filter. A subject image is captured. Then, since a certain pixel has only green data, another pixel has only red data, and the next pixel has only blue data, data of other element colors is complementarily generated from surrounding pixels. . The filter complementing circuit 31 implements such complementing by hardware, and is indispensable in the image pickup device 22 composed of a single CCD device.

In a single-chip CCD, even if the variation in the light receiving sensitivity of each pixel is not large, since a filter called RGB is put on the CCD, the output characteristics may be naturally biased. Although the automatic white balance circuit 32 eliminates such a bias, it is realized by a hardware circuit, so that it is generally averaged or the data distribution in a specific range is fixed. . The main function of the γ correction circuit 33 is to make the light receiving sensitivity of the image sensor 22 flat.

When the data is input, the filter complementing circuit 31 is only executed mechanically as it is. However, the automatic white balance circuit 32 and the γ correction circuit 33 have a correction function designed by a hardware circuit. It is also possible to input a specific instruction from the controller 10 as well, and it is possible to intentionally shift the white balance as described later, or to apply a different γ correction to each element color by a γ correction circuit. This enables active adjustment.

The image data passing through the image processing unit 30 is temporarily stored in the DRAM 40, and is temporarily stored in the DRAM 40.
Reads out image data from the DRAM 40 and performs a predetermined tallying process. The result of the tallying process is input to the controller 10 as the evaluation value of the captured image.
0 reads out the image data to be evaluated from the DRAM 40 and stores it in the flash memory 60. On this occasion,
Since the image data becomes too large if the output image of the image sensor 22 remains as it is, the image data is stored after being converted into a compression format such as JPEG by the encoding unit 70.

In addition, the controller 10 is connected to an operation display section 80, and is provided with an image display panel such as an LCD together with various operation elements such as a shutter button (not shown). Of course, the controller 10 sequentially inputs the operation status of each operator, and displays the captured image on the display panel. Further, as described later, the evaluation result for the captured image is also displayed on the display panel. Further, a strobe light 90 is provided for night photography, and emits light when operated by the operation element or when predetermined judgment processing is performed by the controller 10.

In the present embodiment, the hardware configuration is as described above. However, the configuration as a digital still camera is generally common, and other configurations are naturally possible. Further, in this example, the digital still camera is realized, but the digital still camera can be incorporated and realized.
The controller 10 performs overall control of the present digital still camera. FIGS. 6 and 7 show a schematic control procedure at the time of photographing a subject image by a flowchart.
Schematically, the flow is as follows: first, an image is input as a provisional image, the photographing conditions are corrected based on the image, and the main photographing is performed when the image becomes appropriate.

In step 100, a provisional input instruction is issued. The shutter button gives an instruction for the main shooting by a full stroke, and gives an input of a temporary image by a half stroke. Therefore, the controller 10
Determines that there is a provisional input instruction when a half stroke is detected. When there is a provisional input instruction, the controller 10 executes provisional image input in step 105. The provisional image input means shooting under general shooting conditions. Therefore, the distance measuring unit 2
1a, focusing is performed by the auto-focus mechanism 21b while measuring the distance to the subject, and the exposure and shutter speed are determined while detecting the brightness by the image sensor 22. And outputs the image data corresponding to the image formed by the AGC circuit 23 to the AGC circuit 23. Also in the AGC circuit 23, the gain is automatically adjusted by a predetermined adjustment function, and the output is A / D converted by the A / D converter 24.

Based on the A / D-converted image data, the image processing unit 30 performs filter complementation, white balance adjustment, and γ correction so that the image data that has been adjusted as much as possible in terms of hardware can be used. Generated and the DRAM 40
To end the provisional image input. Next, in steps 110 to 125, the controller 10 simultaneously performs object extraction and tallying processing. This totaling process is performed while sequentially moving the pixel of interest over the entire image data as shown in FIG.

Based on the empirical fact that an object has a sharper image compared to other parts, the present invention determines that pixels whose image is sharp are pixels of the object. In the image data, RGB luminance is represented by a gradation value for each pixel, and the difference of the same data between adjacent pixels is large in an edge portion of the image. This difference is a luminance gradient, which is called an edge degree. In step 110, the edge degree at each pixel is determined. When considering the XY orthogonal coordinates as shown in FIG. 9, the vector of the degree of change of the image can be calculated by obtaining the X-axis direction component and the Y-axis direction component, respectively. In a digital image composed of pixels in the form of a dot matrix, pixels are adjacent to each other in a vertical axis direction and a horizontal axis direction as shown in FIG. 10, and its brightness is represented by f (x, y). In this case, f
(X, y) is R (x, y), G, which is each luminance of RGB.
(X, y), B (x, y), or the entire luminance Y (x, y). Note that R (x, y), G (x , Y), B (x, y) and the overall luminance Y (x, y) cannot be converted without strict reference to a color conversion table or the like. The correspondence may be used.

In FIG. 10, the difference value fx in the X direction and the difference value fy in the Y direction are: fx = f (x + 1, y) -f (x, y) fy = f (x, y + 1) -f It is represented as (x, y). Therefore, the magnitude | g (x, y) | of a vector having these as components is | g (x, y) | = (fx ** 2 + fy ** 2) ** (1 /
2) is expressed as Of course, the degree of edge is | g (x,
y) | Note that, as shown in FIG. 11, pixels are originally arranged vertically and horizontally in a grid pattern, and there are eight adjacent pixels when focusing on the central pixel. Therefore, similarly, the difference between the image data and each adjacent pixel may be represented by a vector, and the sum of the vectors may be determined as the degree of change of the image.

Since the edge degree is obtained for each pixel as described above, a pixel having a larger edge degree than a certain threshold value is determined to be a pixel of an object. Is to be counted.
This counting process will be described later. Then step 12
At 0, the target pixel is moved as shown in FIG. 8, and the processing from step 110 is repeated until it is determined in step 125 that the tallying has been completed for all pixels. Of course, when the processing has been completed for all the pixels, it means that the object pixels have been extracted and the aggregation processing has been completed.

In this example, the extraction is performed on the assumption that the object pixels are sharp pixels, but the present invention is not limited to this. For example, in the case of a snapshot, a person is an object as a subject. Therefore, if a skin color pixel that can be said to be peculiar to a person in a sense is found, it can be said that the object is extracted. Therefore, it may be determined whether or not the pixel is a skin color pixel based on the chromaticity of each pixel, and the number of skin color pixels may be totaled. As for the chromaticity, the xy chromaticity of each pixel is calculated. Now, assuming that the RGB gradation data of the target pixel in the RGB color system is (R, G, B), r = R / (R + G + B) g = G / (R + G + B) Chromaticity coordinates xc in the color system,
xc = (1.1302 + 1.6387r + 0.6215)
g) / (6.7846-3.0157r-0.3857)
g) yc = (0.0601 + 0.9399r + 4.5306)
g) / (6.7846-3.0157r-0.3857)
g) The following relationship is established. Here, since the chromaticity represents the absolute ratio of the color stimulus value without being influenced by the brightness, it can be said that it is possible to determine what kind of object the pixel is based on the chromaticity. . For skin color,
Since the chromaticity of each pixel is within the range of 0.35 <xc <0.400.33 <yc <0.36, if the chromaticity of each pixel is within this range, the pixel is human skin. Thus, it can be said that the object was extracted. Therefore, if it is within such a range, the tallying process may be performed.

Incidentally, the counting process in step 115 corresponds to the image evaluation process in step 130, and the images to be tabulated are different according to the evaluation process. Therefore, first,
The image evaluation processing will be described. In the present embodiment, five items of “contrast”, “brightness”, “color balance”, “saturation”, and “sharpness” are evaluated, and a totaling process is performed to obtain an image evaluation value representing each item. ing. First, the contrast indicates the width of the luminance of the entire image, and the sense of the captured image as a failure is generally when the width of the contrast is narrow. The distribution of the luminance of each pixel of a certain image as a histogram is shown by a solid line in FIG. When the distribution shown by the solid line is taken, the difference between the brightness of the bright pixel and the brightness of the dark pixel is small, but if the brightness distribution spreads as shown by the dashed line, the difference between the brightness of the bright pixel and the brightness of the dark pixel is obtained. Is increased, and the range of contrast is widened.

Therefore, assuming that such a histogram is created, it is necessary to perform an aggregation process using the interval from the maximum value of the luminance to the minimum value of the luminance as the width of the contrast.
In this case, however, the conversion is a luminance, and if the image data has luminance as an element, the aggregation can be directly performed. However, the image data is represented by RGB gradation values (256 gradations). So it doesn't have a luminance value directly. In order to obtain the luminance, it is necessary to perform color conversion to the Luv color space, but this is not a good solution due to the problem of the amount of calculation and the like. Use expressions. Y = 0.30R + 0.59G + 0.11B Assuming that the luminance is represented in this manner, the luminance distribution of the photographic image appears substantially in a mountain shape as shown in FIG. Of course, the position and shape are various. The width of the luminance distribution is determined depending on where the both ends are determined. However, the point where the number of distributions becomes “0” by extending the base cannot be set as the both ends. This is because the number of distributions may change around “0” in the tail part, and the number of distributions changes while approaching “0” without limit statistically.

For this reason, a portion which is shifted inward by a certain distribution ratio from the side where the luminance is the largest and the side where the luminance is the smallest in the distribution range is defined as both ends of the distribution. In the present embodiment, as shown in the figure, the distribution ratio is set to 0.5%.
Of course, this ratio can be changed as appropriate. In this manner, by cutting the upper and lower ends by a certain distribution ratio, white points and black points caused by noise or the like can be ignored. That is, if such processing is not performed, even if there is even one point, a white point or a black point will be at both ends of the luminance distribution. Although it is “0” and the uppermost end is a gradation “255”, such a problem can be solved by setting a part inside 0.5% of pixels from the upper end part as an end part. Disappears. Then, 0.5% of the number of pixels is calculated based on the actually obtained histogram, and the number of distributions is accumulated in order from the upper luminance value and the lower luminance value in the reproducible luminance distribution in order. Then, the luminance value having the value of 0.5% is defined as the maximum luminance Ymax and the minimum luminance Ymin.

The width Ydif of the luminance distribution is equal to the maximum luminance Ymax.
Ymin = Ymax−Ymin Pcont = 100 × Ydif / 255, where the contrast evaluation value Pcont is a perfect score of 100 points. In addition, the process of totalizing the luminance as described above is performed in step 115, and the process of obtaining the evaluation value Pcont is performed in step 130. next,
The lightness will be described. The lightness as the image evaluation value here means an index of the lightness and darkness of the entire image, and is the median (median) of the distribution obtained from the above-described histogram.
Use Ymed. Therefore, the tallying process in this case is performed simultaneously with the tallying process for contrast.
On the other hand, when analyzing the image evaluation value, the following is performed.

The lightness evaluation value Pbrgt is calculated from the following equation using Ymed_target which is a predetermined ideal value. Pbrgt = 100− | Ymed−Ymed_targ
et | Here, if Pbrgt <0, then Pbrgt = 0.
Note that the actual value of the ideal value Ymed_target is "1
06 "is used, but it is not fixed. In addition, it may be possible to change it to reflect the preference. In this case, the brightness is represented by a perfect score of 100 and the median Ym
It is evaluated whether the image is bright depending on whether ed is larger or smaller than the ideal value Ymed_target. For example,
If the median Ymed is "85", the ideal value Yme
Since d_target is smaller than “106”, it is primarily evaluated as “dark”, and secondarily the lightness evaluation value Pbrgt is numerically expressed as “79”. FIG.
In this manner, the brightness evaluation value Pbrgt is changed to the median Ym.
An aspect that changes based on ed is shown in a graph. In this case as well, the process of totalizing the luminance is performed in step 115, and the process of obtaining the evaluation value Pbrgt is performed in step 1.
30.

FIG. 15 shows a histogram of the luminance. When the peaks of the luminance distribution are shifted toward the dark side as shown by the solid line, the peaks are shifted to the bright side as a whole by the broken line. It can be determined that it is preferable to move.
Conversely, when the peaks of the luminance distribution are generally shifted to the bright side as shown by the solid line in FIG. 16, it can be determined that it is preferable to move the peaks to the dark side as a whole by the dotted line. . Next, the color balance will be described. The color balance referred to here is the R component, G
It indicates whether or not there is a certain unbalance tendency between the component and the B component. For example, if a photograph looks reddish and it represents the real situation at the time of shooting, it does not matter if it does not, it can be said that some adverse effect has appeared. However, it can be said that such an imbalance cannot be understood unless it is actually compared with the real situation, so it may not be possible to make an ex post evaluation.

In the present embodiment, this will be evaluated from the uniformity of the frequency distribution for each color. Depending on the situation at the time of shooting, it may be more natural that the frequency distribution of each color component becomes non-uniform, and in such a case, the color should not be corrected. However, if we look back from the results, it is determined that the frequency distribution should be uniform if the frequency distribution of each color component is somewhat similar, and if the frequency distributions are not similar, it should not be uniform. it can.

For this reason, in the tabulation process, a histogram is created for each color component in order to later check the similarity of the frequency distribution for each color component. At this time, the frequency distribution is not obtained for all the gradation values, but the region of 256 gradations is divided into 8 to 16 (n division), and the frequencies belonging to each region are totaled. In the case of eight divisions, as shown in FIG. 17, “0 to 31”, “32 to 63”.
The frequency distribution is calculated for eight areas of “55”. Therefore, in step 115, the process of creating this histogram corresponds.

On the other hand, when the above-described histogram is created for each color component for all the pixels, the number of pixels (r1, r2...
n), (g1, g2 ... gn), (b1, b2 ... bn)
(Here, n = 8) is vectorized as a component. RG
B, feature vectors VR, VG, VB
VR = (r1, r2... Rn) Σri = 1 VG = (g1, g2... Gn) Σgi = 1 VB = (b1, b2... Bn) Σbi = 1 Find the correlation. The cross-correlation is expressed as a dot product: corr_rg = (VR · VG) / | VR | · | VG | corr_gb = (VG · VB) / | VG | · | VB | corr_br = (VB · VR) / | VB | · | VR , The inner product of the vectors can be said to represent the similarity between the two vectors, and the value is "0" to "1". Here, the evaluation value Pbaln of the color balance is represented by 100 points based on the minimum value corr_x. That is, evaluation is performed as Pbaln = 100 × corr_x. Of course, the process of obtaining the evaluation value Pbaln is performed in step 130.

It should be noted that the color balance may be corrected for each of the n-divided regions. However, it is possible to cope with the problem by roughly increasing or decreasing the overall brightness of each color component. The correction of the RGB values using the γ curve may be performed. FIG. 18 shows an adjustment state in which the overall luminance is increased or decreased by using the γ curve in the γ correction circuit 33. If the red component is large in the color balance, the γ correction circuit 33 By adjusting γ, the balance can be adjusted.

Next, the saturation will be described. Here, the saturation refers to the vividness of the entire image.
For example, it is an evaluation as to whether the primary color is captured vividly or grayish. The saturation itself is Lu
Although represented by the size from the reference axis in the uv plane in the v color space, the amount of calculation for converting the color space is enormous as described above. To For this, the following calculation is performed as the saturation alternative value X. X = | G + B−2 × R | Originally, the saturation becomes “0” when R = G = B, and reaches the maximum value when mixing a single color of RGB or a predetermined ratio of any two colors. Although it is possible to directly express the saturation from this property, it is possible to obtain the maximum saturation in the case of cyan, which is a single color of red and a mixed color of green and blue, according to the simplified above equation. Is "0" when is uniform. In addition, green and blue single colors also reach about half of the maximum value. Of course, the expression X '= | R + B−2 × G | X ″ = | G + R−2 × B |

In the tallying process of step 115, the distribution of the histogram for the alternative value X of the saturation is obtained. If the distribution of the histogram for the alternative value X of the saturation is obtained, the saturation is from the minimum value “0” to the maximum value “5”.
11 ", the distribution is roughly as shown in FIG. On the other hand, the analysis of the image evaluation value is performed based on this histogram. That is, a saturation index for this image is determined based on the aggregated histogram. A range occupied by the higher-order “16%” is obtained from the distribution of the saturation alternative value X, and the lowest saturation “S” within this range represents the saturation of this image, and the evaluation value of the saturation Psato is obtained as follows.

Psatur = 25 × (S ** 1/2) / 4 However, if S> 256, Psatur = 100.
When the evaluation value Psato is obtained in this way, if the value of the evaluation value Psato is small, it is preferable to use a filter or the like to emphasize the saturation at the time of shooting. Of course, in step 130, the evaluation value Psato is obtained. Finally, the sharpness will be described. The sharpness as an image evaluation value is evaluated based on the already used edge degree. However, even if the edge degree is obtained for each pixel, the sharpness degree of the image cannot be obtained only by calculating the edge degrees of all the pixels and averaging them. It can be said that the average value is not suitable because the average value easily changes depending on the ratio of the background region. For this reason, it is determined whether or not the pixel is an edge portion, and only when the pixel is an edge portion, the same edge degree Ddif is integrated (Σ
Ddif) and the number of pixels in the edge portion are integrated (@Edge_Pixel). Since the determination as to whether or not this is an edge portion is made substantially by comparison with a certain threshold value, the object pixels need only be summed up and averaged. That is, when analyzing the image evaluation value, the accumulated edge degree (ΣDdif) is calculated by the number of pixels (ΣEdge_Pixe).
l), and the average value Dd of the edge degree in the edge portion
Calculate if_ave. Of course, the larger the average value Ddif_ave of the edge degree is, the sharper the image is. The evaluation value Psharp is Psharp = 4 × Ddif_ave (where Psharp = 1 if Psharp> 100).
00. ). Therefore, in step 115, the integration of the edge degree Ddif and the number of pixels in the edge portion are performed, and in step 130, the average value Ddi of the edge degree is calculated.
f_ave will be obtained.

In step 130, evaluation values are obtained for each of the items "contrast", "brightness", "color balance", "saturation", and "sharpness" so that only the photographing conditions can be observed as in the conventional case. Then, a more specific failure that could not be determined can be determined. Therefore, in step 135, it is determined whether the image is appropriate based on each evaluation value. If the image is not appropriate, a photographing condition correction operation process is performed in step 140. In addition,
FIGS. 20 to 22 show a situation in which such an evaluation value is displayed on the image display panel of the operation display unit 80. FIG. This display is an example of the case where the display is performed in step 130. In the example shown in FIG. 20, "score display" and "evaluation character display" are performed so that each evaluation value is used as a score and "score display" is used to make it easier to realize using symbols and words.

In the "symbol display" and the "evaluation character display", they are classified and displayed based on the score. For example, "70
"-89" points correspond to "good" or "O", "90" points or more correspond to "very good" or "◎", and "50-69" points correspond to "normal" or "normal". “△” is assigned, and “49” or less is assigned as “bad” or “x”. On the other hand, as described above, since each evaluation value is a perfect score, a total score is displayed in the case of a score display, and an average score is calculated in a similar manner for symbol display and evaluation character display while displaying the total score. Determine display symbols and display characters.

On the other hand, in the example of FIG. 21, the evaluation value is displayed as a bar graph, and in the example of FIG. 22, a star chart is displayed. In the case of the star chart display, the total area is not displayed because the internal area connected by a straight line corresponds to the total. Of course, these displays are only examples, and are not necessarily required. As shown in FIG. 7, in the photographing condition correction operation, while re-evaluating the photographing condition based on the evaluation value obtained as described above,
This is reflected in the shooting conditions. For example, step 20
At 0, it is determined whether the contrast is low and whether the image is dark based on the evaluation value Pcont or the evaluation value Pbrgt. If the contrast is low or the image is dark, the flash flag is turned on in step 205. If the strobe flag is ON, the strobe 90 will emit light at the next shooting. It can be considered that such a relationship is obtained by re-evaluating the photographing conditions with respect to the evaluation value of the image, and obtaining a result that there is room for increasing the contrast or that it is preferable to photograph the image brighter. . This means that the flash 90 is controlled so that the evaluation is reflected in the photographing conditions.

Although it is generally preferable to reflect the photographing conditions in the evaluation of the image, it is more kind to inform the photographer of the reflection result. Is displayed on the image display panel of the operation display unit 80. In this example, the photographing conditions are reflected by emitting light from the strobe 90, but this also means that the exposure amount is increased. Therefore, if there is an optical diaphragm mechanism, it can be reflected in the photographing conditions by opening it. Further, when the image pickup device 22 including a CCD device is provided as in the present embodiment, it is possible to increase the exposure time by increasing the charging time of the CCD device. Of course,
In these cases, the reverse control is also possible.

In step 215, the evaluation value Pbal
It is determined whether or not the color balance is large based on n. If the bias is large, step 220
The gain of the AGC circuit is individually adjusted for each element color. For example, when it is found that the balance is that the red component is lower than the other components, the gain for the red pixel may be increased. In the case of a single CCD element, the gain may be adjusted for each pixel covered with a filter of each element color, and in the case of a three CCD element, the gain of the AGC circuit may be adjusted for each CCD element.

In any case, it can be said that, based on the evaluation value of the image, a poor color balance caused by natural conditions or unbalance of the CCD element was found as a photographing condition, and this was reflected in the photographing condition. Also in this case, in step 225, a message to shift the color balance is displayed on the operation display unit 80. Next, in step 230, the evaluation value Psharp
It is determined whether or not the sharpness is low based on. To increase the sharpness, the focus position may be changed by the auto-focus mechanism 21b. However, when the distance is measured by the triangulation method in the distance measuring unit 21a, the focus target becomes a fixed position in the shooting range. Therefore, the only way to change the focus is to shift the shooting range. Therefore, a warning to correct framing is displayed on the operation display unit 80 in step 235. In this case, it can be said that, based on the evaluation of the image, the deficiency of the photographing condition that the sharpness of the object is reduced in the normal auto focus is evaluated.

However, the autofocus is performed by the distance measuring unit 21a.
In the case where is not used, it is also possible to increase the sharpness by changing the photographing conditions. For example, autofocus may be performed by obtaining a spatial frequency in real time based on image data. That is, the spatial frequency of a part of the image is obtained, and the focus position can be changed such that the spatial frequency is closer to the high frequency side. If it is determined that the sharpness is not good after the evaluation, it is possible to change the part of the image for which the spatial frequency is to be obtained. For example, the spatial frequency is determined at the center of the image until then, but it is often effective to change the spatial frequency to a part slightly lower than the center of the image. When shooting a human image, the center of the object can be said to be the center of the image if shooting up, but when shooting the entire human body, the human body image will fit in the part from the center of the image to the lower side Because there are many. In addition, since the image may be photographed vertically, in this case, it can be said that it is effective to focus on the region from the central region to the right side of the screen. Therefore, the focus position is sequentially changed with reference to the frequency of use. What should I do?

Finally, at step 240, the evaluation value Psa
It is determined whether the vividness is high or low based on tu. It is completely unknown how to determine the effect of vividness. That is, there is a case where the color of the subject itself lacks vividness, and as an external factor, an illumination condition or the like can also influence. Therefore, what can be done on the camera side can only propose that "it is recommended that a color emphasis filter be installed because the vividness is low due to some factor," and the like. Therefore, in step 245, a warning that the color emphasis filter should be attached is displayed on the operation display unit 80. Also in this case, it can be said that the evaluation of the photographing condition such as the lighting condition was performed based on the result of evaluating the image.

In FIG. 23, the automatic adjustment items of the photographing conditions may be displayed so that the operator can select which element should be automatically adjusted. In this case, the selection result is stored as a flag, and this flag is stored in step 20.
It may be determined whether or not to perform the above-described correction operation with reference to 0, 215, 230, and 240. On the other hand, in Steps 210 and 225, various messages are displayed while the photographing conditions are corrected. However, as shown in FIG. You may do it. For example,
If the contrast is poor, an evaluation such as "weakness of illumination has been detected" or "it seems better to emit a strobe light" may be displayed. Of course, in this case, a manual adjustment method to be reflected on the photographing condition may be displayed together. Such a change in the display can be realized only by displaying a corresponding message from the evaluation value of the image in accordance with the determination shown in FIG.

When the photographing condition correcting operation is completed, a provisional image is input again in step 105, and the above-described evaluation is performed.
As described above, in the photographing condition correcting operation, there are those that can correct the photographing conditions and those that cannot. Those that can be corrected are corrected by re-inputting the temporary image, but those that cannot be corrected may still be judged to be improper. Therefore, although not explicitly shown in the flowchart, when a warning message is displayed for a shooting condition that cannot be corrected, a flag is set in accordance with the evaluation value, and a second step 1 is executed.
When it is determined at 35 that the image is appropriate, the flag is referred to, and if the flag is set, it is ignored even if the evaluation value is bad.

When the image is appropriate, the image under the condition is actually photographed and taken in step 145 and stored in the DRAM 40 as described above.
The encoding unit 70 converts the data into a compression format such as JPEG and stores it in the flash memory 60. next,
The operation of the present embodiment having the above configuration will be described. If the photographer wants to take a picture with no more failures than normal auto shooting, he will try to half-stroke the shutter button. Then, the CP in the controller 10
U11 detects this half stroke at step 100 in the main routine, determines that there is a provisional input instruction, and executes provisional image input at step 105. In this provisional image input, photographing is performed under general photographing conditions. Therefore, focusing is performed by the autofocus mechanism 21b while measuring the distance to the subject by the distance measuring unit 21a as usual, and brightness is measured by the image sensor 22. Is detected to determine the exposure and shutter speed, and an appropriate timing and an appropriate gain of the AGC circuit 23 are automatically adjusted based on the exposure and shutter speed.

Then, under such photographing conditions, the image sensor 2
2 is output to the AGC circuit 23, amplified by the adjusted gain and A / D converted by the A / D converter 24, and then filtered by the image processing unit 30. Complementation, white balance adjustment, and gamma correction are performed. These adjustments are as much as possible in terms of hardware.
The data is written to the RAM 40.

Next, the controller 10 executes step 110
In steps 125 to 125, object extraction and tabulation processing are performed at the same time, and in step 130, referring to the tabulation results, "contrast", "brightness", "color balance",
Image evaluation values are obtained for five items of “saturation” and “sharpness”. Further, it is determined whether or not the image is appropriate in step 135 based on the evaluation value of the obtained image,
If it is not appropriate, a photographing condition correction operation is executed in step 140 in order to reflect the evaluation value on the photographing condition.

By performing the photographing condition correcting operation,
If the contrast is low, a strobe will be fired at the next photographing, and the bias of the color balance will be corrected. In other words, focusing on only the shooting conditions, adjusting the hardware as much as possible and evaluating the image actually captured by the provisional image input, if there is still a bad point, In order to make this more favorable, it will be reflected in the photographing conditions. Therefore,
By performing the actual photographing in step 145 under the photographing conditions reflected in such a manner, it is possible to make the photographing more difficult to fail. Further, the image data obtained by the actual shooting is stored in the flash memory 60 in the encoding unit 70 in a predetermined compression format.

As described above, in step 105, the imaging unit 2
After saving the image data taken at step 0 in the DRAM 40, the CPU 11 in the controller 10 proceeds to step 110.
In steps 125 to 125, an aggregation process is performed based on the image data, and in step 130, an evaluation value for the image is obtained based on the aggregation result.
The photographing condition is corrected in step 140 as necessary while judging whether or not the image is appropriate based on the same evaluation value, and the photographing condition is reflected from the actually photographed image data. The number of photographing failures is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of an electrophotographic imaging apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a digital still camera to which the electrophotographic imaging device is applied.

FIG. 3 is a block diagram of a controller in the digital still camera.

FIG. 4 is a block diagram of an imaging unit in the digital still camera.

FIG. 5 is a block diagram of an image processing unit in the digital still camera.

FIG. 6 is a flowchart of a main routine in the digital still camera.

FIG. 7 is a flowchart of a photographing condition correcting operation in the digital still camera.

FIG. 8 is a diagram illustrating a state in which a processing target pixel is moved.

FIG. 9 is an explanatory diagram in a case where the degree of change of an image is represented by each component value of rectangular coordinates.

FIG. 10 is an explanatory diagram in a case where the degree of change of an image is obtained by a difference value between adjacent pixels in the vertical axis direction and the horizontal axis direction.

FIG. 11 is an explanatory diagram in a case where the degree of change of an image is obtained between all adjacent pixels.

FIG. 12 is a diagram illustrating a distribution range when a luminance distribution is expanded.

FIG. 13 is a diagram illustrating edge processing of a luminance distribution and edges obtained by the edge processing.

FIG. 14 is a graph showing how the evaluation value of brightness changes.

FIG. 15 is a diagram showing a concept of increasing brightness by γ correction.

FIG. 16 is a diagram showing a concept of darkening by γ correction.

FIG. 17 is a diagram illustrating a method of extracting an element to be used as a feature vector for each color component.

FIG. 18 is a diagram showing a correspondence relationship of luminance changed by γ correction.

FIG. 19 is a schematic diagram of a tallying state of a saturation distribution.

FIG. 20 is a diagram showing an evaluation value display screen when comprehensive display is selected.

FIG. 21 is a diagram showing an evaluation value display screen when bar graph display is selected.

FIG. 22 is a diagram showing an evaluation value display screen when star chart display is selected.

FIG. 23 is a diagram showing a list display screen when an automatic adjustment item is selected.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Controller 11 ... CPU 12 ... ROM 13 ... RAM 14 ... Bus 20 ... Imaging part 21 ... Optical system path 21a ... Distance measuring part 21b ... Autofocus mechanism 22 ... Imaging element 23 ... AGC circuit 24 ... A / D converter 30 ... Image processing unit 31 Filter complement circuit 32 Automatic white balance circuit 33 Gamma correction circuit 40 DRAM 50 Image evaluation unit 60 Flash memory 70 Encoding unit 80 Operation display unit 90 Strobe

Claims (10)

[Claims] An image of a subject is taken through an optical path while setting predetermined photographing conditions, and the subject image is represented by dot-matrix pixels, and a predetermined elemental color obtained by color separation for each pixel. Image capturing means for acquiring the represented image data; image evaluating means for performing numerical tabulation processing on the acquired image data to evaluate a captured image based on a predetermined evaluation criterion; An electrophotographic imaging apparatus comprising: a photographing condition evaluation unit that evaluates the photographing condition in the imaging unit. 2. The electrophotographic imaging apparatus according to claim 1, wherein the image evaluation unit extracts a pixel of an object in the subject image based on the image data, and converts the image data of the pixel of the object into an image. An electrophotographic imaging apparatus, wherein the tallying process is performed as a target to evaluate a captured image. 3. The electrophotographic image pickup apparatus according to claim 1, wherein said image pickup means is capable of changing said photographing condition, and said photographing condition evaluation means is capable of changing a photographed image. An electrophotographic imaging apparatus, wherein an imaging condition in the image imaging means is controlled so that an evaluation based on the image is reflected in the imaging condition. 4. The electrophotographic image pickup apparatus according to claim 3, wherein the image pickup means includes a strobe for illuminating a subject image, and the image evaluation means evaluates the brightness of the subject image. An electrophotographic imaging apparatus, wherein the photographing condition evaluation means operates a strobe in the image imaging means when the image evaluation means determines that an object in the subject image is dark. 5. An electrophotographic image pickup apparatus according to claim 3, wherein said image pickup means is configured to output an image of a subject on an image pickup surface via said optical path. An image sensor that performs photoelectric conversion with pixels in a dot matrix form, and an amplifier circuit that amplifies a conversion output of the image sensor at a predetermined amplification factor, wherein the image evaluation unit performs evaluation of brightness in the subject image, The photographing condition evaluating means increases the amplification factor in the amplifier circuit when the image evaluating means determines that the object in the subject image is dark, and decreases the amplification factor when determining that the object is bright. Electrophotographic imaging device. 6. The electrophotographic image pickup apparatus according to claim 3, wherein the image pickup means comprises:
An aperture for adjusting the amount of light in the optical system path; the image evaluation means evaluates brightness of the subject image; and the photographing condition evaluation means determines that the object in the subject image is dark. An electrophotographic imaging apparatus characterized in that the aperture is opened when the shutter is opened, and the aperture is controlled in the direction to stop when it is determined that the aperture is bright. 7. The electrophotographic image pickup apparatus according to claim 3, wherein the image pickup means comprises:
An auto-focus mechanism for automatically adjusting the optical system path so as to focus on a predetermined subject in the subject image, wherein the image evaluation means evaluates the sharpness of the image in the subject image, and The electrophotographic imaging apparatus is characterized in that when the image evaluation means determines that the subject image is not sharp, the autofocus mechanism changes the focused subject to an object. 8. The electrophotographic image pickup apparatus according to claim 3, wherein the image pickup means comprises:
It is possible to generate a tone value for lightness and darkness for each of a plurality of element colors and individually adjust the output.
The color balance of the subject image is evaluated, and the photographing condition evaluating means adjusts the output for each element color when the image evaluating means evaluates the color balance of the subject image as unbalanced. Electrophotographic imaging device. 9. An image of a subject is taken through an optical path while setting predetermined photographing conditions, and the subject image is represented by dot matrix pixels, and gradation is determined by a predetermined element color obtained by color separation for each pixel. An electrophotographic imaging method for acquiring expressed image data, comprising: an image imaging step of acquiring an image data by imaging a subject image under the imaging conditions; and performing a numerical tallying process on the acquired image data. An electronic photograph comprising: an image evaluation step of evaluating a captured image based on a predetermined evaluation criterion; and a shooting condition evaluation step of evaluating the shooting conditions in the image shooting step based on the evaluation. Imaging method. 10. An image of a subject is taken via an optical path while setting predetermined photographing conditions, and the subject image is represented by dot matrix pixels, and gradation is determined by a predetermined element color obtained by color separation for each pixel. A medium storing an electrophotographic imaging control program which is controlled by a computer when acquiring the expressed image data, comprising: An image evaluation step of performing a numerical tabulation process on the image data and evaluating a captured image based on a predetermined evaluation criterion; and a photographic condition evaluation for evaluating the photographic conditions in the image imaging step based on the evaluation. And a recording medium storing an electrophotographic imaging control program.