JP4648186B2 - Digital camera characteristic evaluation method, digital camera characteristic evaluation apparatus - Google Patents

Description

The present invention is an evaluation index used for selecting an optimal electronic image capturing device (for example, a digital camera) that matches the dynamic range of the subject and for setting an optimal digital camera that matches the dynamic range of the subject. The present invention relates to a method for evaluating gradation reproduction characteristics of a digital camera and a characteristic evaluation apparatus for a digital camera.

In recent years, electronic image capturing apparatuses that directly shoot a subject and directly create an electronic image have become widespread. Electronic image capturing apparatuses mainly include digital cameras that capture still images and digital video cameras that capture moving images. (Hereafter, the electronic image capturing device is described as a digital camera, but the meaning is not limited.) The subject to be photographed with a digital camera has various brightness levels from dark to bright. There is a part of. For example, when shooting a black-haired person wearing white clothes, the hair is dark but the clothes are bright. The ratio of the luminance between the bright part and the dark part of the subject is called the subject gradation reproduction range (dynamic range).

On the other hand, a digital camera cannot capture the entire gradation reproduction range, and the gradation reproduction range that can be photographed is determined depending on the model. Further, the gradation reproduction range can be changed by setting the digital camera.

Here, the gradation reproduction range is a range from the minimum exposure amount to the maximum exposure amount that can be effectively received by the digital camera, and is represented by the difference between the two values (EV value). Here, EV is an abbreviation for Exposure Value. The exposure amount is adjusted by changing the aperture and shutter speed of the digital camera and the sensitivity of the light receiving element (hereinafter referred to as light receiving sensor).

When a subject having a gradation reproduction range wider than that of a digital camera is photographed, there is a problem that the gradation is skipped in the bright part and the dark part is crushed. Furthermore, the gradation reproduction range is not digitized with the same weighting, and there are models that are strong in bright areas and models that are strong in dark areas, depending on the camera model. Therefore, it is important to select and set an appropriate digital camera in accordance with the gradation reproduction characteristics of the subject. In addition, the illumination conditions applied to the subject can be changed in accordance with the gradation reproduction characteristics of the digital camera.

Here, the gradation reproduction characteristics are the gradation reproduction range described above, and the shape of a gradation reproduction curve (details will be described later) that corresponds to the change in the exposure amount and the change in the gradation of the captured image data. It is a concept that includes it.

For that purpose, it is necessary to grasp the gradation reproduction characteristics of the digital camera. As a method for grasping the gradation reproduction characteristics of a digital camera, for example, in Patent Document 1, a test chart is provided in a box having an imaging light source that is not affected by an external light source and an illumination light source inside. A technique for measuring and evaluating the gradation reproduction range of this digital camera by photographing a test chart through a photographing opening using a digital camera stored and provided outside the box is disclosed. (Prior art 1)
Japanese Patent Application No. 10-528625 (pages 14-15, FIG. 11)

However, in the prior art 1, since a specially devised box is used, it is necessary to become familiar with the operation of the apparatus, and there is a drawback that it cannot be easily and simply measured. Further, the conventional technique 1 has a problem that it takes time and effort to take a trial shot in order to confirm that the photographed image data does not have any gradation skip or collapse.

The present invention has been made in consideration of such a conventional technique, and an object of the present invention is to provide a method for easily measuring and evaluating the gradation reproduction characteristics of a digital camera, and the gradation reproduction characteristics of a digital camera. It is an object of the present invention to provide an apparatus for easily measuring and evaluating the above.

The present invention solves the above problems by the following means. That is, the invention of claim 1 relates to an electronic image capturing device including a light receiving sensor, a plurality of exposure conditions that define the amount of light input to the light receiving sensor, and a shooting setting that associates an exposure amount when shooting under the exposure conditions. A method for grasping gradation reproduction characteristics using data and image data including image name information associated with an exposure condition and a gradation value of a pixel, wherein an electronic image is obtained according to the exposure condition selected from the shooting setting data An electronic image shooting device setting step for setting a shooting device, an image data creation step for shooting a target subject for each of the plurality of exposure conditions, and creating a plurality of image data, and a pixel of interest from each of the image data And obtaining the image name information from the image data, referring to the shooting setting data, and associating it with the image name information A pixel exposure amount corresponding data creation step for selecting correspondence value between the gradation value of the pixel of interest and the acquired exposure amount by selecting an exposure amount value of the exposure condition, and the correspondence data From the first exposure amount calculation step for calculating the first exposure amount value when the gradation value of the pixel rises from the minimum value and the corresponding data, the gradation value of the pixel reaches the maximum value. A second exposure amount calculating step for calculating a second exposure amount value at the time of saturation, and a difference between the exposure amount values from the first exposure amount value and the second exposure amount value . A method of grasping gradation reproduction characteristics of an electronic image photographing apparatus, characterized in that the procedure includes a gradation reproduction range data creation step of creating gradation reproduction range data as values .

The invention according to claim 2 is a procedure including a gradation reproduction curve creating step of creating a gradation reproduction curve from the corresponding data. This is a method for grasping tone reproduction characteristics.

According to a third aspect of the present invention, there is provided the gradation reproduction characteristic grasping method for an electronic image photographing apparatus according to the second aspect, wherein the gradation reproduction curve is represented by a graph.

By expressing the gradation reproduction curve as a graph, the gradation reproduction characteristics can be visualized.

According to a fourth aspect of the invention, there is provided the gradation reproduction characteristic grasping method for an electronic image photographing apparatus according to the second aspect, wherein the gradation reproduction curve is expressed by a mathematical expression.

By expressing the gradation reproduction curve by a curve equation, the value of the gradation reproduction characteristic can be calculated.

The invention according to claim 5 uses a subject having a completely diffusing surface as the subject to be targeted, and the method for grasping gradation reproduction characteristics of the electronic image photographing device according to claims 1 to 4. It is.

Therefore, by using a subject having a completely diffusing surface as a subject, anyone can easily and easily create image data without using a special device and selecting a measurement place.

According to a sixth aspect of the present invention, in the method for grasping gradation reproduction characteristics of an electronic image photographing device according to any one of the first to fifth aspects, the exposure condition is a shutter speed value of the electronic image photographing device. is there.

In other words, by using the shutter speed value of the electronic image photographing device as the exposure condition data, it is possible to set various and fine photographing conditions without changing the quality of the photographed image.

The invention according to claim 7 is a gradation reproduction characteristic evaluation system for an electronic image photographing apparatus configured by connecting an electronic image photographing apparatus including a light receiving sensor and an electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus via a network. The electronic image capturing apparatus includes exposure condition data including information for specifying exposure condition data and an exposure condition that defines a light amount input to the light receiving sensor, image name information associated with the exposure condition, and pixel level. Storage means for storing image data including tone values, exposure condition data receiving means for receiving desired exposure condition data, and pixel data having a gradation value when imaged in accordance with the desired exposure conditions A light receiving sensor stored in the storage area and image name information associated with a desired exposure condition, obtaining the pixel data, and acquiring the image name information and the pixel An image photographing apparatus comprising: image data creating means for creating image data including tone values; and image data transmitting means for acquiring the image data and transmitting the image data, wherein the electronic image photographing apparatus gradation The reproduction characteristic evaluation apparatus includes shooting setting data in which a plurality of exposure conditions that define the amount of light input to the light receiving sensor and exposure amounts when shooting under the exposure conditions, and image name information associated with the exposure conditions And storage means for storing image data including pixel gradation values, exposure condition data transmission means for acquiring desired exposure conditions from shooting setting data, and generating and transmitting exposure condition data, and the image An image data receiving means for receiving data, a gradation value of a pixel of interest from the image data, and image name information from the image data to obtain a shooting setting data; A pixel that selects a value of an exposure amount of an exposure condition associated with image name information and creates correspondence data between the gradation value of the pixel of interest and each of the acquired exposure amounts From the exposure amount correspondence data creating means, the first exposure amount calculation means for calculating the value of the first exposure amount when the gradation value of the pixel rises from the minimum value from the correspondence data, and the correspondence data Second exposure amount calculating means for calculating a second exposure amount value when the gradation value of the pixel reaches a maximum value and is saturated, and the first exposure amount value and the second exposure amount value Tone reproduction range data creating means for creating gradation reproduction range data that is a value obtained as a difference in exposure amount value from, and tone reproduction curve creating means for creating a gradation reproduction curve from the corresponding data; Gradation reproduction characteristics including gradation reproduction range data and gradation reproduction curve data An electronic image photographing apparatus gradation reproduction characteristic evaluation system, comprising: an evaluation apparatus comprising gradation reproduction characteristic data creation means for creating data.

The invention according to claim 8 is the electronic image photographing apparatus gradation reproduction characteristic evaluation system according to claim 7, wherein the exposure condition is a shutter speed value of the electronic image photographing apparatus.

The invention according to claim 9 is an electronic image photographing device gradation reproduction characteristic evaluation device using image data created by an electronic image photographing device including a light receiving sensor, wherein a plurality of exposures defining the amount of light input to the light receiving sensor Storage means for storing shooting setting data associating conditions and exposure amounts when shooting under the exposure conditions, and image data including image name information and pixel gradation values associated with the exposure conditions; An exposure condition data transmitting unit that obtains a desired exposure condition from the shooting setting data and generates and transmits the exposure condition data, an image data receiving unit that receives the image data, and a gradation of a pixel of interest from the image data And obtaining the image name information from the image data, referring to the shooting setting data, and calculating the exposure amount value of the exposure condition associated with the image name information. The pixel exposure value corresponding data creation means for creating correspondence data between the gradation value of the pixel of interest and each of the acquired exposure amounts, and the gradation value of the pixel is minimized from the correspondence data. A first exposure amount calculating means for calculating a first exposure amount value when rising from the value, and a second exposure amount when the gradation value of the pixel reaches a maximum value and is saturated from the corresponding data. A second exposure amount calculation means for calculating the value of the first exposure amount, and tone reproduction range data which is a value obtained as a difference between the exposure amount values from the first exposure amount value and the second exposure amount value Gradation reproduction range data creation means, gradation reproduction curve creation means for creating a gradation reproduction curve from the corresponding data, and gradation reproduction characteristic data including gradation reproduction range data and gradation reproduction curve data Gradation reproduction characteristic data creating means An electronic imaging device tone reproduction characteristic evaluation apparatus.

According to a tenth aspect of the present invention, in the electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus according to the ninth aspect, the exposure condition is a shutter speed value of the electronic image photographing apparatus.

According to an eleventh aspect of the present invention, by incorporating the computer into a computer, the electronic image photographing device gradation reproduction characteristic evaluation system according to any one of claims 7 to 10, or the electronic image photographing device gradation reproduction. A computer program that operates as a characteristic evaluation apparatus.

A twelfth aspect of the present invention is a computer-readable recording medium on which the computer program according to the eleventh aspect is recorded.

According to the present invention, the gradation reproduction characteristics of a digital camera can be easily and easily evaluated by anyone at any time, anywhere, without requiring a special device. In addition, since an appropriate digital camera corresponding to the exposure condition of the subject can be selected using the characteristic evaluation result of the digital camera, the efficiency of photographing work by the digital camera is improved. Furthermore, it is possible to easily set optimal illumination conditions for the digital camera.

(Example)
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is an overall configuration diagram of an electronic image photographing apparatus gradation reproduction characteristic evaluation system 1 according to the present invention. The electronic image photographing device gradation reproduction characteristic evaluation system 1 is configured by connecting an electronic image photographing device gradation reproduction characteristic evaluation device 100 and an electronic image photographing device 300 (for example, a digital camera) via a network 900. The electronic image shooting apparatus gradation reproduction characteristic evaluation apparatus 100 includes shooting setting data 192 in which a plurality of exposure conditions and exposure amounts are associated, exposure condition data 191 including an exposure condition selected from the shooting setting data 192, and a digital camera. Image data 399 received from 300, gradation reproduction range data 197, gradation reproduction curve 198, and digital camera characteristic evaluation data 195 are stored.

The digital camera 300 creates image data 399 by photographing the subject 700 under the exposure condition of the exposure condition data 191 received from the electronic image photographing device gradation reproduction characteristic evaluation device 100, and creates an electronic image photographing device gradation. It transmits to the reproduction characteristic evaluation apparatus 100.

Here, there are methods for setting the exposure conditions, such as changing the shutter speed, aperture, and sensitivity of the light receiving sensor. For the reasons described below, the method for changing the shutter speed is optimal, so the exposure condition data An example of setting a shutter speed value as an exposure condition will be described in 191.

One of the reasons why the method of changing the shutter speed is optimal is that the method of changing the aperture causes a problem that the depth of the subject changes and changes the captured image. Further, in the method of changing the sensitivity of the light receiving sensor, the S / N of the light receiving sensor changes, and there is a problem that noise increases when the sensitivity is increased. On the other hand, the method of changing the shutter speed does not cause such an adverse effect.

The reason why the method of changing the shutter speed is optimal is that the method of changing the sensitivity of the aperture and the light receiving sensor determines the maximum value and the minimum value of the setting of the aperture and the light receiving sensor. Since there are few types of values that can be set between the value and the minimum value, the imaging conditions are greatly restricted. An example of the diaphragm will be described later. On the other hand, in the method of changing the shutter speed, various and fine photographing conditions can be set.

Examples of the connection method of the network 900 include a USB method, TCP / IP, IEEE1394, and a serial method.

Note that the electronic image photographing device gradation reproduction characteristic evaluation device 100 and the digital camera 300 of the electronic image photographing device gradation reproduction characteristic evaluation system 1 may not be connected to a network. At this time, examples of the storage medium used for data exchange include a hard disk and a flash memory (such as a card-shaped and stick-shaped flash memory).

FIG. 2 is a detailed configuration diagram of the electronic image photographing apparatus tone reproduction characteristic evaluation system according to the present invention. The electronic image photographing apparatus gradation reproduction characteristic evaluation system 1 is configured by connecting an electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus 100 and a digital camera 300 via a network 900.

The electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus 100 includes a control unit 105, an exposure condition data transmission unit 110, an image data reception unit 120, a photographing setting data creation unit 132, and a pixel exposure amount correspondence data creation unit 131. A first exposure amount calculation unit 133, a second exposure amount calculation unit 135, a gradation reproduction range data generation unit 137, a gradation reproduction curve generation unit 139, and a digital camera characteristic evaluation data generation unit 140. Storage means 190. The storage unit 190 includes exposure condition data 191, shooting setting data 192, image data exposure amount related data 194, digital camera characteristic evaluation data 195, correspondence data 196, gradation reproduction range data 197, and gradation reproduction. The curve 198 and image data 399 are stored.

The shooting setting data 192 includes information for specifying an exposure condition (for example, a serial number), an exposure condition (for example, a shutter speed value) that defines the amount of light input to the light receiving sensor, and exposure amount information (for example, an exposure amount value). It is included data. The exposure condition data 191 is data including a desired shutter speed value. The image data 399 is data including image name information (for example, an image name) associated with the exposure condition and a pixel gradation value. The image data exposure amount related data 194 is data that associates the value of the exposure amount with the pixel name. Corresponding data 196 is data that associates the value of the exposure amount with the gradation value of the pixel. The digital camera characteristic evaluation data 195 is data associating information for identifying a digital camera (for example, the name of the photographing apparatus) with the gradation reproduction range data 197, and is, for example, a digital camera characteristic evaluation table.

The control means 105 sets an initial value “1” for the control parameter “i”. The exposure condition data transmission unit 110 transmits exposure condition data 191 (for example, shutter speed setting data including a desired shutter speed value).

The image data receiving unit 120 receives image data taken according to the transmitted exposure condition data 191.

The shooting setting data creating unit 132 acquires exposure condition setting information (for example, a shutter speed value and an exposure amount value) input by the evaluator 500, and information for specifying shooting setting data (for example, shooting setting data). Photographic setting data including an exposure condition (for example, shutter speed value) and an exposure value (for example, EV value) that define the light quantity input to the light receiving sensor.

The pixel exposure amount correspondence data creating unit 131 obtains the tone value of the pixel of interest from the image data 399, obtains image name information (image name) from the image data 399, and transmits exposure condition data 191. Then, from the order in which the image data 399 is received, the image name information is associated with the exposure condition, the exposure setting value associated with the image name information is selected with reference to the shooting setting data 192. The correspondence data 196 between the gradation value of the pixel of interest and the acquired exposure amount is created.

Note that the pixel exposure amount correspondence data creation unit 131 may have the following procedure. That is, the pixel exposure amount correspondence data creating unit 131 acquires image name information (image name) from the image data, transmits the exposure condition data 191 and receives the image data 399 as the exposure condition from the order of reception. Reference is made to the shooting setting data 192, the exposure amount of the exposure condition associated therewith is acquired, and the image data exposure amount related data 194 that associates the exposure amount value with the image name of the image data is created. Furthermore, the gradation value of the pixel of interest and the image name are acquired from the image data, and the exposure value associated with the image name is obtained by referring to the image data exposure amount related data 194. Then, the correspondence data 196 between the exposure value and the tone value of the pixel of interest is created.

The first exposure amount calculation unit 133 calculates the value of the first exposure amount when the gradation value of the pixel rises from the minimum value from the corresponding data. The second exposure amount calculation unit 135 calculates a second exposure amount value when the gradation value of the pixel reaches the maximum value and is saturated from the corresponding data. The tone reproduction range data creating unit 137 creates tone reproduction range data that is a value obtained as a difference between the exposure amount values from the first exposure amount value and the second exposure amount value. The tone reproduction curve creating means 139 creates a tone reproduction curve (for example, a graph or a curve equation) from the corresponding data.

By the way, when the gradation value of the pixel data rises from the minimum value, it is a limit state where the gradation is not crushed, and when the gradation value of the pixel data is saturated, it is a limit state where the gradation does not skip It is.

Moreover, the gradation reproduction characteristic can be visualized by expressing the gradation reproduction curve as a graph.

On the other hand, the gradation reproduction characteristic value can be calculated by expressing the gradation reproduction curve by a curve equation. The curve equation generated from the pixel exposure value and the gradation value can be expressed by, for example, a set of line segments connecting two points (a pair of two adjacent exposure value and gradation values), It can be expressed by a spline curve at each point, or by an n-order curve (second-order, third-order, quartic curve, etc.) at each point.

The digital camera characteristic evaluation data creating means 140, from the gradation reproduction range data 197 of each digital camera, digital camera characteristic evaluation data 195 in which the photographing device name that uniquely identifies the digital camera is associated with the gradation reproduction range data 197. Create

Control means 105, exposure condition data transmission means 110, image data reception means 120, photographing setting data creation means 132, pixel exposure amount corresponding data creation means 131, first exposure amount calculation means 133, and second The exposure amount calculation means 135, the gradation reproduction range data creation means 137, the gradation reproduction curve creation means 139, and the digital camera characteristic evaluation data creation means 140 are computer programs. The storage unit 190 is a memory. Exposure condition data 191, shooting setting data 192, image data exposure amount related data 194, digital camera characteristic evaluation data 195, correspondence data 196, gradation reproduction range data 197, gradation reproduction curve 198, image Data 399 is data readable by a computer program.

The digital camera 300 includes an exposure condition data receiving unit 310, a light receiving sensor 320, an image data creating unit 330, an image data transmitting unit 340, and a storage unit 390. The storage unit 390 stores pixel data 391 and image data 399.

The pixel data 391 is data having a gradation value. The image data 399 is data including an image name and a pixel gradation value.

The exposure condition data receiving unit 310 receives exposure condition data 191 (for example, shutter speed setting data). The light receiving sensor 320 acquires a shutter speed value from the exposure condition data 191 and stores pixel data 391 having gradation values photographed according to the shutter speed value in a predetermined storage area (for example, an image memory).

The image data creation means 330 acquires the pixel data 391 and creates image data 399 including the exposure value and the pixel gradation value. The image data transmission unit 340 transmits image data.

The exposure condition data receiving unit 310, the image data transmitting unit 340, and the image data creating unit 330 are computer programs. The light receiving sensor 320 is a light receiving element. The storage unit 190 is a memory. The digital camera characteristic evaluation data 195 is text data readable by a computer program. The pixel data 391 is bitmap data that can be read by a computer program. The image data 399 is data that can be read by a computer program.

FIG. 3 shows a subject 700 having a completely diffusing surface shape. A completely diffusing surface is a surface that reflects light having the same luminance when viewed from any direction. For example, magnesium oxide, barium sulfate or the like is thickly applied to the complete diffusion surface.

In photographing using a subject 700 having a completely diffusing surface, it is possible to obtain a uniform exposure amount that does not depend on the illumination angle or the photographing angle, and the digital camera 300 can be easily and anywhere without being restricted by the photographing location. Can be taken. Further, it is not necessary to use a special device.

FIG. 4 is an example of the shutter speed value. A predetermined shutter speed value is set in the exposure condition data 191. For example, “1/5000”, “1/4000”, “1/2000”, “1/30”, “1/15”, and the like.

FIG. 5 is an explanatory diagram of a procedure for obtaining the gradation reproduction range. When the subject 700 is photographed by changing the shutter speed, the aperture, or the sensitivity of the light receiving element of the digital camera, the pixel exposure amount changes accordingly.

For example, when the shutter speed is very fast, the exposure amount from the subject 700 to the digital camera 300 is small, and the gradation of the photographed image is crushed (FIG. 5A). As the shutter speed gradually decreases, the exposure amount from the subject 700 to the digital camera 300 increases, and the gradation value of the pixel data of the digital camera 300 also increases correspondingly. Abundant gradation of captured images can be obtained (FIG. 5 (a)). Further, when the shutter speed is slowed down, the exposure amount becomes excessive and the gradation of the photographed image is skipped (FIG. 5 (c)).

Although an example in which measurement is performed by changing the shutter speed has been described, instead of changing the aperture or changing the sensitivity of the light receiving element of the digital camera 300, the gradation reproduction range can be obtained similarly. We can easily guess what we can do.

In this way, the gradation reproduction range of a digital camera can be easily measured by anyone at any time, anywhere, without using a special device.

Therefore, since the gradation reproduction range of the digital camera can be grasped, the bright part (highlight) and dark part (shadow) of the subject are measured with an exposure meter, and the difference is within the gradation reproduction range of the digital camera. By selecting and shooting, it can be confirmed before shooting that image data can be shot without gradation skipping or collapse.

In this way, by checking the gradation reproduction range, a digital camera suitable for subject characteristics (for example, shooting a subject with a large difference in light and darkness, shooting a subject with a small difference in brightness and a subtle gradation) Can be selected quickly.

FIG. 6 is an example of the shooting setting data 192. In the shooting setting data 192, a number, a shutter speed value, and an exposure amount (EV) are associated with each other. In FIG. 6, for example, “number = 001, shutter speed value (seconds) = 1/4000, exposure amount (EV) = 1”, “number = 002, shutter speed value (seconds) = 1/2000, exposure. Examples are “amount (EV) = 2”,..., “Number = 008, shutter speed value (seconds) = 1/30, exposure amount (EV) = 8”,.

FIG. 7 is an example of the correspondence data 196. In the correspondence data 196, an exposure amount (EV) and a gradation value are associated with each other. In FIG. 7, “exposure amount (EV) = 1, gradation value = 0”,..., “Exposure amount (EV) = 8, gradation value = 40”,.

FIG. 8 is an example of the image data exposure amount related data 194. In the image data exposure amount related data 194, an exposure amount (EV) and an image name are associated with each other. FIG. 8 illustrates “exposure amount (EV) = 1, image name = 001.jpg”, “exposure amount (EV) = 2, image name = 002.jpg”, and the like.

FIG. 9 is an explanatory diagram of a procedure for creating correspondence data according to the present invention. For example, the eighth exposure condition of the shooting setting data 192 is “shutter speed value (seconds) = 1/30”, and the exposure condition data 191 including this is generated and transmitted to the digital camera 300. (FIG. 9 (1)).

The exposure condition data 191 is transmitted and the image data 399 is received from the digital camera 300 by knowing that it is the image data 399 (image name = 008.jpg) taken under the eighth exposure condition from the order of receiving the image data 399 ( (2)).
With reference to the shooting setting data 192, the exposure amount = 8 (EV) under the eighth exposure condition is acquired ((3) (4)).
The image name = 008.jpg and the exposure amount = 8 are associated and recorded in the image data exposure amount related data 194 ((5)).

With reference to the image data exposure amount related data 194, the exposure amount = 8 associated with the image name = 008.jpg is obtained ((6)),
The tone value = 40 of the pixel of interest in the image data 399 (image name = 008.jpg) photographed under the eighth exposure condition is acquired ((7)), and this “exposure amount = 8” and “floor” The key value = 40 ”is associated and recorded in the correspondence data 196.

FIG. 10 is a tone reproduction curve (tone reproduction characteristic graph) generated from the pixel exposure value and the tone value. The vertical axis is the gradation value of the pixel, and the horizontal axis is the exposure value (EV value). Pixel data at the same coordinate position is selected from each image data photographed by changing the exposure amount using the shutter speed setting data 191 and graphed. For example, in this graph, the gradation value is the minimum “gradation value = 0” while the exposure value is between “EV value = 0 and 3”. When the exposure value exceeds “EV value = 3”, the gradation value also increases. When the exposure value reaches “EV value = 13”, the gradation value reaches the maximum “gradation value = 255” and is saturated. Even if the exposure value increases to “EV value = 13 or more”, the gradation value does not increase. From this, the gradation reproduction range of this digital camera is exemplified as “10 EV” which is the difference between “EV value = 3” and “EV value = 13”.
FIG. 11 is a flowchart of the electronic image capturing apparatus gradation reproduction characteristic evaluation system. Note that in the communication between the electronic image photographing device gradation reproduction characteristic evaluation device 100 and the digital camera 300, exposure condition data and image data are transmitted and received. In the electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus 100,
(1) The shooting setting data creation unit 132 acquires exposure condition setting information (for example, a shutter speed value and an exposure value) input by the evaluator 500, and specifies the exposure condition and the light receiving sensor. The shooting setting data 192 including the exposure condition that defines the amount of light input to is generated. (Step S100)
(2) The control means 105 sets an initial value “1” for the control parameter “i”. (Step S105)
(3) The exposure condition data transmission unit 110 creates and transmits exposure condition data 191i (shutter speed value) including the i-th exposure condition of the shooting setting data 192. (Step S110)
(4) The image data receiving unit 120 receives the i-th image data 399. (Step S120)
(5) The pixel exposure amount correspondence data creation unit 131 records the image data exposure amount related data 194 in association with the value of the i-th exposure amount of the shooting setting data 192 and the image name of the i-th image data. (Step S130)
(6) The pixel exposure amount correspondence data creation unit 131 acquires the gradation value of each pixel of the i-th image data. At the same time, the pixel exposure amount correspondence data creating unit 131 acquires the i-th image name, refers to the image data exposure amount related data 194, and selects the exposure amount value associated with the image name. (Step S140)
(7) The pixel exposure amount correspondence data creation unit 131 creates correspondence data 196 between the i-th exposure amount value and the gradation value. (Step S150)
(8) If there is an exposure condition not transmitted, “1” is added to i, and the process returns to step S110. When all exposure conditions have been transmitted, the process proceeds to the next step. (Step S160)
(9) The gradation reproduction range data creation unit 137 obtains the gradation reproduction range 197 using the correspondence data 196 between the exposure condition and the gradation value. (Step S180)
(10) The gradation reproduction curve creating means 139 creates a gradation reproduction curve 198 (for example, a gradation reproduction characteristic graph) from the corresponding data. finish. (Step S190)

Note that in steps S130 to S150, the pixel exposure amount correspondence data creating unit 131 does not create the image data exposure amount related data 194 but refers to the shooting setting data 192 directly from the image data 399. Data 196 may be created.

In the digital camera 300,
(1) The exposure condition data receiving unit 310 receives exposure condition data 191 including the value of the i-th shutter speed. (Step S200)
(2) The light receiving sensor 320 sets the shutter speed value of the i-th exposure condition data 191. (Step S210)
(3) The light receiving sensor 320 images the subject 700. (Step S220)
(4) The image data creation unit 330 creates the i-th image data 399 including the i-th image name and the pixel value. (Step S230)
(5) The image data transmission unit 340 transmits the i-th image data 399. (Step S240)

A modification will be described.
(Modification 1)
FIG. 12 is a modification of the flowchart of the electronic image capturing apparatus gradation reproduction characteristic evaluation system. In the electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus 100,
(1) Same as step S100 to step S130 in FIG. (From step S300 to step S330)
(2) If there is an untransmitted exposure condition, “1” is added to i, and the process returns to step S110. When all exposure conditions have been transmitted, the process proceeds to the next step. (Step S340)
(3) The control means 105 sets an initial value “1” for the control parameter i. (Step S345)
(4) Same as step S140 in FIG. (Step S350)
(5) Same as step S150 in FIG. (Step S360)
(6) If there is image data for which the correspondence data between the i-th exposure condition and the gradation value has not been created, “1” is added to i, and the process returns to step S350. When the correspondence data of the gradation value of the pixel of interest in all the image data is created, the process proceeds to the next step. (Step S370)
(7) Same as step S180 to step S190 in FIG. (Step S380 to Step S390)

(Modification 2)
FIG. 13 is a detailed configuration diagram of the gradation reproduction characteristic evaluation system 2 that is not connected to the network (off-line) electronic image photographing apparatus.
The electronic image photographing device gradation reproduction characteristic evaluation system 2 that is not connected to the network is composed of an electronic image photographing device gradation reproduction characteristic evaluation device 100a and an electronic image photographing device 300a.

The electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus 100a includes an exposure condition data recording means 110a, an image data receiving means 120a, and means excluding the exposure condition data transmitting means 110 and the image data receiving means 120 from the means shown in FIG. And comprising. The storage unit 190 stores the same data as in FIG.

The exposure condition data recording unit 110a records the exposure condition data 191 on a storage medium. The image data receiving unit 120a receives image data recorded on a storage medium.

The electronic image photographing apparatus 300a includes an exposure condition data receiving unit 310a, an image data recording unit 330a, a light receiving sensor 320, and a storage unit 390.
The storage unit 390 stores the same data as in FIG.

The exposure condition data receiving unit 310a receives the exposure condition data 191 recorded on the storage medium. The image data recording unit 330a acquires the pixel data 391, creates image data 399 including the exposure value of the subject and the gradation value of the pixel data, and records the image data 399 on the storage medium.

The exposure condition data recording unit 110a and the image data recording unit 330a are writer devices. The exposure condition data receiving unit 310a and the image data receiving unit 120a are reader devices.

Incidentally, examples of the storage medium include a hard disk and a flash memory.

(Reference) Explanation will be made with reference to aperture setting data. FIG. 14 shows a format and an example of the aperture setting data 191. In the aperture setting data, a predetermined aperture value (referred to as F value) is set. For example, the F value is “F1.4”, “F2”, “F2.8”, “F4”, “F5.6”, “F8”, and the like.

As described above in detail, according to the present invention, it is possible to easily and easily evaluate the gradation reproduction characteristics of a digital camera at any time, anywhere, without requiring a special device. became. Moreover, since the digital camera characteristic evaluation result can be used to select an appropriate digital camera according to the exposure condition of the subject, the efficiency of the shooting operation by the digital camera is improved. Furthermore, it has become possible to easily set optimal lighting conditions for digital cameras.

1 is an overall configuration diagram of an electronic image photographing apparatus gradation reproduction characteristic evaluation system according to the present invention. Detailed configuration diagram of the tone reproduction characteristics evaluation system for electronic imaging equipment Subjects with a completely diffusing surface shape Examples of shutter speed values Explanatory diagram of the procedure for obtaining the gradation reproduction range Example of shooting setting data Corresponding data example Example of image data exposure amount related data 194 Procedure for creating correspondence data according to the present invention Gradation reproduction curve (gradation reproduction characteristic graph) Flowchart of electronic image photographing device gradation reproduction characteristic evaluation system (Modification 1) Flowchart of electronic image photographing apparatus gradation reproduction characteristic evaluation system (Modification 2) Detailed configuration diagram of gradation reproduction characteristic evaluation system 2 for electronic image photographing apparatus not connected to network (Reference) Format and example of aperture setting data

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic image photographing device gradation reproduction characteristic evaluation system 2 Electronic image photographing device gradation reproduction characteristic evaluation system 100 not connected to network 100 Electronic image photographing device gradation reproduction characteristic evaluation device 105 Control means 110 Exposure condition data transmission means 110a Exposure condition data recording Means 120 Image data receiving means 120a Image data receiving means 130 Gradation reproduction characteristic data creating means 131 Pixel exposure amount corresponding data creating means 132 Shooting setting data creating means 133 First exposure amount calculating means 135 Second exposure amount calculating means 137 Tone reproduction range data creation means 139 Tone reproduction curve creation means 140 Digital camera characteristic evaluation data creation means 190 Storage means 191 Exposure condition data 192 Shooting setting data 194 Image data Exposure related data 195 Digital camera characteristic evaluation data 196 Corresponding data 97 gradation reproduction range data 198 gradation reproduction curve data 300 electronic image photographing device 310 exposure condition data reception means 310a exposure condition data reception means 320 light receiving sensor 330 image data creation means 330a image data recording means 340 image data transmission means 390 storage means 391 Pixel data 399 Image data 500 Evaluator 700 Subject 900 Network

Claims (12)

An electronic image capturing apparatus including a light receiving sensor, a plurality of exposure conditions that define the amount of light input to the light receiving sensor, and shooting setting data that associates exposure amounts when shooting under the exposure conditions, and the exposure conditions A method of grasping gradation reproduction characteristics using image data including image name information and pixel gradation values,
An electronic image shooting device setting step for setting an electronic image shooting device in accordance with an exposure condition selected from the shooting setting data;
An image data creation step of photographing a target subject for each of the plurality of exposure conditions and creating a plurality of image data;
The tone value of the pixel of interest is acquired from each image data, the image name information is acquired from the image data, and the exposure amount of the exposure condition associated with the image name information is obtained by referring to the shooting setting data. A corresponding data creation step for creating correspondence data between the gradation value of the pixel of interest and each of the acquired exposure amounts;
A first exposure amount calculating step of calculating a first exposure amount value when the gradation value of the pixel rises from a minimum value from the corresponding data;
A second exposure amount calculating step of calculating a second exposure amount value when the gradation value of the pixel reaches a maximum value and is saturated from the corresponding data;
A tone reproduction range data generating step of generating a tone reproduction range data is a value calculated as the difference between the exposure value from the value of the first exposure value and the second exposure,
A method for grasping gradation reproduction characteristics of an electronic image photographing device, characterized in that the method is performed by a procedure including: 2. The method of grasping gradation reproduction characteristics of an electronic image photographing apparatus according to claim 1, wherein the gradation reproduction curve creating step of creating a gradation reproduction curve from the corresponding data is performed. 3. The method of grasping gradation reproduction characteristics of an electronic image photographing apparatus according to claim 2, wherein the gradation reproduction curve is represented by a graph. 3. The method of grasping gradation reproduction characteristics of an electronic image photographing apparatus according to claim 2, wherein the gradation reproduction curve is expressed by a mathematical expression. The method for grasping gradation reproduction characteristics of an electronic image photographing apparatus according to any one of claims 1 to 4, wherein a subject having a perfect diffusion surface is used as the target subject. 6. The method of grasping gradation reproduction characteristics of an electronic image photographing device according to claim 1, wherein the exposure condition is a shutter speed value of the electronic image photographing device. In a gradation reproduction characteristic evaluation system of an electronic image photographing apparatus configured by connecting an electronic image photographing apparatus including a light receiving sensor and an electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus via a network,
The electronic image capturing apparatus includes exposure condition data including information for specifying exposure condition data and an exposure condition that defines a light amount input to the light receiving sensor, image name information associated with the exposure condition, and pixel levels. Storage means for storing image data including tone values, exposure condition data receiving means for receiving desired exposure condition data, and pixel data having a gradation value when imaged in accordance with the desired exposure conditions A light receiving sensor to be stored in the storage area, image name information associated with a desired exposure condition is created, the pixel data is acquired, and image data including the image name information and a gradation value of the pixel is obtained. An image photographing apparatus comprising: image data creating means to create; and image data transmitting means for acquiring the image data and transmitting the image data,
The electronic image photographing device gradation reproduction characteristic evaluation device is:
Shooting setting data associating a plurality of exposure conditions that define the amount of light input to the light receiving sensor and exposure amounts when shooting under the exposure conditions, image name information associated with the exposure conditions, and pixel gradation values Storage means for storing image data including:
Exposure condition data transmitting means for acquiring desired exposure conditions from the shooting setting data and generating and transmitting exposure condition data; and
Image data receiving means for receiving the image data;
The tone value of the pixel of interest is acquired from the image data, the image name information is acquired from the image data, and the exposure setting of the exposure condition associated with the image name information is obtained by referring to the shooting setting data. A corresponding data creating means for selecting the value and creating corresponding data between the gradation value of the pixel of interest and each of the acquired exposure amounts;
A first exposure amount calculating means for calculating a first exposure amount value when the gradation value of the pixel rises from the minimum value from the corresponding data;
Second exposure amount calculating means for calculating a second exposure amount value when the gradation value of the pixel reaches a maximum value and is saturated from the corresponding data;
Gradation reproduction range data creating means for creating gradation reproduction range data, which is a value obtained as a difference between exposure dose values from the first exposure dose value and the second exposure dose value;
A tone reproduction curve creating means for creating a tone reproduction curve from the corresponding data;
Tone reproduction characteristic data creating means for creating gradation reproduction characteristic data including gradation reproduction range data and gradation reproduction curve data. Evaluation system. 8. The electronic image photographing apparatus gradation reproduction characteristic evaluation system according to claim 7, wherein the exposure condition is a shutter speed value of the electronic image photographing apparatus. An electronic image photographing device gradation reproduction characteristic evaluation device using image data created by an electronic image photographing device including a light receiving sensor,
Shooting setting data associating a plurality of exposure conditions that define the amount of light input to the light receiving sensor and exposure amounts when shooting under the exposure conditions, image name information associated with the exposure conditions, and pixel gradation values Storage means for storing image data including:
Exposure condition data transmitting means for acquiring desired exposure conditions from the shooting setting data and generating and transmitting exposure condition data; and
Image data receiving means for receiving the image data;
The tone value of the pixel of interest is acquired from the image data, the image name information is acquired from the image data, and the exposure setting of the exposure condition associated with the image name information is obtained by referring to the shooting setting data. A corresponding data creating means for selecting the value and creating corresponding data between the gradation value of the pixel of interest and each of the acquired exposure amounts;
A first exposure amount calculating means for calculating a first exposure amount value when the gradation value of the pixel rises from the minimum value from the corresponding data;
Second exposure amount calculating means for calculating a second exposure amount value when the gradation value of the pixel reaches a maximum value and is saturated from the corresponding data;
Gradation reproduction range data creating means for creating gradation reproduction range data, which is a value obtained as a difference between exposure dose values from the first exposure dose value and the second exposure dose value;
A tone reproduction curve creating means for creating a tone reproduction curve from the corresponding data;
Gradation reproduction characteristic data creating means for creating gradation reproduction characteristic data including gradation reproduction range data and gradation reproduction curve data;
An electronic image photographing apparatus gradation reproduction characteristic evaluation apparatus comprising: The exposure condition is a shutter speed value of the electronic image capturing apparatus;
The electronic image photographing device gradation reproduction characteristic evaluation device according to claim 9. A computer that, when incorporated in a computer, causes the computer to operate as the electronic image photographing device gradation reproduction characteristic evaluation system or the electronic image photographing device gradation reproduction characteristic evaluation device according to any one of claims 7 to 10. program. The computer-readable recording medium which recorded the computer program of Claim 11.

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