JP4780338B2 - Imaging device evaluation method - Google Patents

Description

  The present invention relates to an imaging device evaluation chart for simultaneously evaluating “dynamic range”, “resolution”, and “false color” of a digital camera, and an imaging device evaluation method using such an imaging device evaluation chart, The present invention relates to an imaging apparatus evaluation program.

  In recent years, as a device for taking photographs (images), there has been a transition from a silver salt camera using a film to a digital camera using an image sensor such as a CCD (Charge Coupled Devices) or a CMOS (Complementary Metal Oxide Semiconductor). ing. There are many types of digital cameras with various functions in the market, but the ones that occupy a large percentage of the selection criteria when users select digital cameras are images taken with digital cameras. Can mention the quality.

  The main factors that determine the quality of images taken with a digital camera include the “dynamic range”, “resolution”, and “false color” of the digital camera.

  The dynamic range refers to the difference between light and dark that can be recognized by the digital camera. If the dynamic range of the digital camera is wider (larger), it is possible to obtain a high-quality image with richer gradations.

  The resolution is an index indicating how small an image captured by a digital camera can be distinguished. If a smaller one can be identified, it can be said that the quality of the image is higher.

  The false color is a color blur that occurs in an image in the vicinity of a sharp edge when a photographing object having a sharp edge is photographed. This false color is generated due to the influence of the arrangement of the image sensors of the digital camera and the method of complementary calculation between pixels of the image sensor.

As a method for evaluating various factors that determine the quality of an image acquired by such a digital camera, for example, a method described in Japanese Patent Application Laid-Open No. 2006-5509 is known.
In the evaluation method of Patent Document 1, data for a characteristic evaluation image is created on a personal computer, the created characteristic evaluation image is displayed on an LCD within a light shielding range, and the displayed image is displayed with a digital camera. The digital camera's output signal is taken into a personal computer, and the dynamic range, resolution, and white balance of the digital camera are evaluated.

Further, an ISO 12233 resolution chart or the like has been proposed as an evaluation chart to be photographed when evaluating a digital camera. This ISO 12233 resolution chart is used only for evaluating the resolution of a digital camera.
JP 2006-5509 A

  The digital camera evaluation method of Patent Document 1 can evaluate the dynamic range, resolution, and white balance of the digital camera, but has a problem that it cannot evaluate the false color as described above.

  In addition, since the digital camera evaluation method of Patent Document 1 requires a specially configured device, it is not possible to perform a simple evaluation of the digital camera in an environment normally used for shooting in a studio or the like. There is.

  As an evaluation chart, an ISO 12233 resolution chart has been proposed. However, this resolution chart has a problem that it can be used only for evaluating the resolution of the imaging apparatus.

  In the conventional evaluation chart, it is difficult to create black and white having a sufficient contrast so that the dynamic range can be measured. Further, in such a chart, unevenness is caused by how the light is applied. Therefore, the conventional evaluation chart has a problem that an accurate dynamic range cannot be easily measured, and an accurate white balance cannot be easily acquired.

  The present invention is for solving the above-described problems. First, an imaging apparatus capable of simultaneously and simply evaluating the “dynamic range”, “resolution”, and “false color” of a digital camera. It is to provide an evaluation chart. The imaging device evaluation chart of the present invention is characterized in that there are white portions having sufficient spatial frequencies, various angles of edges, and reflectivity in the chart. For example, such a white portion has a reflectance of 1 in the entire wavelength region such as a complete diffusion surface.

  A second object of the present invention is to provide a method for evaluating an imaging apparatus such as a digital camera using the imaging apparatus evaluation chart as described above. In this imaging apparatus evaluation method, shooting is performed while changing the exposure amount of the imaging apparatus, and the dynamic range, resolution, and false color of the imaging apparatus are evaluated from the correspondence between the exposure amount and the output value of the imaging apparatus. .

  A third object of the present invention is to provide an imaging apparatus evaluation program for realizing the imaging apparatus evaluation method as described above. With the imaging apparatus evaluation method and imaging apparatus evaluation program as described above, it is possible to easily evaluate “dynamic range”, “resolution”, and “false color” in one setting.

For the purpose of the present invention as described above, the invention according to claim 1 is a white belt-like band at a different interval from the dynamic range evaluation photographing target portion formed of a white complete diffusing surface having a reflectance of 1 in all wavelength regions. And a plurality of patterns that alternate alternately with a black belt-like part, and several types of resolution evaluation shooting target parts from a low frequency pattern to a high pattern, and a white part and a black part at various angles with respect to the vertical direction An imaging device evaluation chart having at least a false color evaluation imaging target portion composed of a boundary portion of the imaging device is photographed by the imaging device, and photographing with the smallest exposure amount while reducing the shutter speed from the fastest shutter speed of the imaging device The process of acquiring photographed image data with the largest exposure amount from the image data, and the dynamic range evaluation of the photographed image data The process of displaying / outputting the luminance obtained from the average value or RGB value and the EV value when the captured image data is captured, and among the captured image data, the RGB value is close to 240 and the black value is the RGB value Is a step of selecting photographed image data for resolution evaluation / false color evaluation close to 20, (RGB values take values from 0 to 255), and for the photographed image data for resolution evaluation / false color evaluation Resolution evaluation For several types of patterns from low frequency patterns to high patterns in the shooting target area, determine whether the interval between black parts can be recognized, and whether the white part between black parts can be recognized as white. A step of notifying a level corresponding to a pattern for which the threshold value is a limit, and a red channel of RGB values in a false color evaluation photographing target portion for resolution evaluation and false color evaluation; Calculate the (R−G) histogram that is the difference between the green channels, the (GB) histogram that is the difference between the Green channel and the Blue channel, and the (B−R) histogram that is the difference between the Blue channel and the Red channel. (RG) Calculation / display / output of “maximum value”, “minimum value”, “standard deviation” in difference value histogram, (GB) “maximum value”, “minimum value” in difference value histogram, Calculating, displaying, and outputting “standard deviation”, and calculating, displaying, and outputting “maximum value”, “minimum value”, and “standard deviation” in the (BR) difference value histogram. This is an evaluation method for an imaging apparatus.

According to a second aspect of the present invention, in the evaluation method for an imaging apparatus according to the first aspect, the complete diffusion surface is a coated surface of magnesium oxide.

According to a third aspect of the present invention, in the evaluation method for an imaging apparatus according to the first aspect, the complete diffusion surface is a barium sulfate coating surface.

  According to the imaging apparatus evaluation chart, the imaging apparatus evaluation method, and the imaging apparatus evaluation program according to the embodiment of the present invention, the “dynamic range”, “resolution”, and “false color” of the imaging apparatus can be simultaneously and easily performed. Can be evaluated.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The “imaging device” in this specification includes a digital still camera, a digital camera function mounted on a mobile phone, a still photo imaging function such as a video camera, and the like.

  FIG. 1 is a diagram showing an imaging device evaluation chart according to an embodiment of the present invention. In FIG. 1, 10 is an imaging device evaluation chart, 11 is a dynamic range evaluation photographing target portion, 12 is a resolution evaluation photographing target portion, and 13 is a false color evaluation photographing target portion. The imaging device evaluation chart 10 includes at least approximately three main parts. The three main parts are a shooting target part (11) for evaluating the dynamic range, a shooting target part (12) for evaluating the resolution, and a shooting target part (13) for evaluating the false color. It should be noted that the imaging device evaluation chart may include a portion to be imaged other than those for evaluation.

  It is desirable that the dynamic range evaluation photographing target part 11 constituting a part of the imaging apparatus evaluation chart 10 of the present invention is a white complete diffusion surface as an ideal state. The completely diffusing surface is a surface having the same luminance when viewed from any direction, and can be constituted by, for example, magnesium oxide, barium sulfate, or the like applied at a predetermined thickness.

  When photographing the dynamic range evaluation photographing target portion 11 (completely diffusing surface) by the imaging device, it is possible to obtain a uniform exposure amount without depending on the illumination angle and photographing angle at the time of photographing. However, in this method, evaluation is possible even if it is not a complete diffusion surface, and it is possible to perform evaluation by using a white or black portion in the imaging apparatus evaluation chart 10 for the time being. Here, the exposure amount is the amount of light input to the image pickup device of the image pickup apparatus, and is expressed by EV (Exposure Value). For example, EV is 15 when the aperture is F11 and the shutter speed is 1/250 seconds. FIG. 26 is a relationship diagram of the shutter speed, aperture value, and EV value of the imaging apparatus.

  In addition, the resolution evaluation photographing target portion 12 constituting a part of the imaging apparatus evaluation chart 10 of the present invention is a pattern in which black and white binary is periodically repeated, and includes several types from a low frequency pattern to a high pattern. In this example, seven patterns are shown, but the number of patterns is not limited to this. As an example of such a pattern, an example in which a white belt portion and a black belt portion are alternately repeated in the horizontal direction is shown. However, such a pattern may be provided in the vertical direction. Further, the horizontal width of the white belt-like portion and the horizontal width of the black belt-like portion are set to the same length. In addition, a frequency here shall mean the space | interval in which a black strip part (or white strip part) is repeated. The pattern located below the resolution evaluation photographing target portion 12 is defined as a lower frequency pattern.

  When such a resolution evaluation photographing target portion 12 is photographed with an imaging device, if the width of the white belt portion and the black belt portion is large, photographed image data can be obtained so that the black and white lines appear to be separated. When the line width of the white belt portion and the black belt portion becomes small and exceeds a predetermined limit, captured image data that makes it difficult to determine the boundary between these black and white lines is obtained. Such captured image data that is difficult to distinguish between black and white lines is the limit of resolution.

  The false color evaluation photographing target part 13 constituting a part of the imaging apparatus evaluation chart 10 of the present invention is, for example, 0 °, 45 °, 90 °, 135 °, 180 °, 225 clockwise from the 12 o'clock direction. It is characterized by comprising a figure having black and white binary boundary portions of various angles such as °, 270 °, and 315 °.

FIG. 2 is a diagram showing a false color evaluation photographing target part extracted from the imaging device evaluation chart according to the embodiment of the present invention. In FIG. 2, symbols such as A and B for clearly indicating the boundary portion between the white portion and the black portion are added. In the example of FIG. 2A, the boundary line AA ′ is a boundary portion between a white portion and a black portion of 90 ° (or 270 °), and the boundary line BB ′ is 135 ° (or 315 °). The boundary portion between the white portion and the black portion, the boundary line CC ′ is the boundary portion between the white portion and the black portion at 0 ° (or 180 °),
The boundary line DD ′ provides a boundary portion between a white portion and a black portion of 45 ° (or 215 °), respectively. In addition, the boundary part which is not attached | subjected the symbol in FIG. 2 (A) can be considered similarly.

  In the example of FIG. 2B, the boundary line AA ′ is a 0 ° (or 180 °) white portion and a black portion, and the boundary line BB ′ is 45 ° (or 215 °). ) Of the white portion and the black portion, the boundary line CC ′ is 90 ° (or 270 °) the boundary portion of the white portion and the black portion, and the boundary line DD ′ is 135 ° (or 315 °), a boundary portion between a white portion and a black portion is provided.

  The photographing portion at the boundary portion between the white portion and the black portion configured as described above is used for evaluation of false colors.

  In the embodiment shown in FIG. 2, the false color evaluation photographing target portion 13 is shown as an example in increments of 45 °, but may be configured at an angle other than 45 °. Further, it is desirable that the thickness of the line when configuring the false color evaluation photographing target portion 13 is composed of a line having a thickness larger than that which can be resolved by the imaging apparatus, and several types of figures having different thicknesses are created. As shown in FIG.

  3 and 4 are diagrams showing another example of the false color evaluation photographing target portion of the imaging device evaluation chart according to the embodiment of the present invention.

FIGS. 3A and 3B show other modes of the false color evaluation photographing target portion 13 according to FIG.
FIG. 3A shows an example in which the boundary portion between the white portion and the black portion of the false color evaluation photographing target portion 13 is in increments of 60 °. FIG. 3B shows the false color evaluation photographing target portion 13. The case where the boundary portion between the white portion and the black portion is on the circumference (that is, an example of the boundary portion with an increment close to 0 °) is shown.

  4A and 4B show other modes of the false color evaluation photographing target portion 13 according to FIG. 4A shows a case where the black line of the false color evaluation imaging target portion 13 is thicker than that shown in FIG. 2B. FIG. 4B shows the false color evaluation imaging target portion 13. The boundary portion between the white portion and the black portion is shown as an example in increments of 22.5 °.

  Next, the imaging method of the imaging apparatus evaluation chart 10 of the present invention configured as described above will be described. FIG. 5 and FIG. 6 are diagrams illustrating an arrangement relationship between the imaging device evaluation chart 10, the imaging device, and the light source when the imaging device evaluation chart 10 is captured. 5 and 6, 10 is an imaging device evaluation chart, 20 is an imaging device, 30 is a wall surface, 40 is a light source, and 50 is a tripod. FIG. 5 is a view of each arrangement relationship as seen from above, and FIG. 6 is a view of the photographing environment of the imaging device evaluation chart 10 as seen from the side.

  The imaging device 20 includes general electronic devices capable of taking still images such as a digital still camera, a digital camera function mounted on a mobile phone, and a still photo imaging function such as a video camera. In the present invention, the imaging apparatus evaluation chart 10 is photographed by such an imaging apparatus 20, and “dynamic range”, “resolution”, and “false color” are evaluated based on the photographed data.

  The imaging device evaluation chart 10 is fixed by being attached to a wall 30 such as a wall or a board that the light source 40 does not reflect. The light source 40 is installed in such an arrangement as to irradiate obliquely from the front as shown in the horizontal direction center line of the imaging device evaluation chart 10.

  The imaging apparatus is installed so that the imaging apparatus evaluation chart 10 and the imaging apparatus 20 have the same height, and an imaging element surface (not shown) of the imaging apparatus 20 and the imaging apparatus evaluation chart 10 plane are parallel to each other. The distance between the imaging device evaluation chart 10 and the imaging device 20 is determined as a position where the imaging device evaluation chart 10 can fill the imaging screen.

  Next, the evaluation procedure of the imaging / imaging device 20 of the imaging device evaluation chart 10 will be described. FIG. 7 is a diagram showing an outline of an evaluation flow of the image pickup apparatus according to the embodiment of the present invention. FIG. 7 shows a flow when the imaging device A and the imaging device B are compared, but the number of imaging devices to be compared is not limited to this. In the present invention, the imaging device A and the imaging device B are compared to determine which imaging device is better based on resolution, dynamic range, and false color. Also, an evaluation material for comparing the imaging device A and the imaging device B is provided.

  In FIG. 7, the process starts in step S100. Then, first, in step S101, the imaging device evaluation chart 10 is installed as described above. Subsequently, in step S102, the imaging device evaluation chart 10 is captured by the imaging device A. In step S103, the imaging device evaluation chart 10 is captured by the imaging device B. In step S104, dynamic range, resolution, and false color evaluation characteristics are obtained based on the captured image data captured in steps S102 and 103, and the imaging device A and the imaging device B are compared with each other. In step S105, the flow ends.

  Next, a more specific imaging method of the imaging device evaluation chart 10 will be described with reference to FIG. FIG. 8 is a diagram showing a flowchart of the captured image data acquisition process in the imaging apparatus evaluation according to the embodiment of the present invention.

  In FIG. 8, when the captured image data acquisition process is started in step S200, the imaging device evaluation chart 10 is installed in the above-described manner in step S201. Next, in step S202, the imaging device 20 is installed as described above.

  In step S203, the aperture and ISO sensitivity of the imaging device 20 are set to appropriate values. Next, in step S <b> 204, the imaging device evaluation chart 10 is photographed at the fastest shutter speed of the imaging device 20. Next, in step S205, the white balance is set so that the white portion in the captured image data of the image capturing apparatus 20 is equal to RGB. As such a white part, the part which image | photographed the white perfect diffusion surface of the dynamic range evaluation imaging | photography target part 11 of the imaging device evaluation chart 10 can be used.

  Next, in step S206, after the white balance is adjusted, the imaging device evaluation chart 10 is shot again. In step S207, the RGB value of the dynamic range evaluation photographing target unit 11 is examined based on the photographed image data photographed in step S206. Then, it is determined whether or not the value of the portion where the dynamic range evaluation photographing target portion 11 is photographed is (0, 0, 0).

  When the result of determination in step S207 is YES, the process proceeds to step S208, and when the result of determination in step S207 is NO, the process proceeds to step S213.

In step S213, which proceeds when the result of determination in step S207 is NO, settings are made so that the RGB value of the dynamic range evaluation photographing target portion 11 is (0, 0, 0).
That is, in step S213, the RGB value of the dynamic range evaluation photographing target unit 11 is set to (0, 0, 0) by performing any one or a combination of the following three items.

    -Increase the aperture value of the lens unit of the imaging device 20 to reduce the amount of light incident on the imaging device.

    -Lower the ISO sensitivity to suppress the amount of light that the imaging device of the imaging device reacts.

    ・ Reduce the light intensity of the light source to darken the shooting environment.

  When the setting is made in step S213, photographing is performed again in step S206, and it is determined in step S207 whether the RGB value of the dynamic range evaluation photographing target portion 11 is the minimum gradation value (0, 0, 0). .

  In step S208 that proceeds when the result of the determination in step S207 is YES, the imaging device evaluation chart 10 is photographed by the imaging device 20. In step S209, the captured image data captured in step S207 is stored.

  Next, in step S210, the imaging device evaluation chart 10 is photographed with the shutter speed of the imaging device 20 lowered by one step. In step S211, the captured image data captured in step S210 is stored. It should be noted that for an imaging apparatus that can slow down the shutter speed by 1/2 or 1/3, shooting is performed while slowing the shutter speed in such steps. In the present invention, in essence, the captured image data is acquired while gradually reducing the exposure amount with the smallest possible number of steps from the fastest shutter speed of the imaging apparatus.

  Next, in step S212, it is determined whether or not the value of the dynamic range evaluation photographing target portion 11 is the maximum gradation value (255, 255, 255). In this embodiment, the case where the gradation is 8 bits for each color has been described as an example. However, the present invention is not limited to the number of bits for such gradation expression.

  When the determination result in step S212 is YES, the process proceeds to step S214, and when the determination result in step S212 is NO, the process proceeds to step S210.

  If the determination result in step S212 is NO, the process enters a loop in which captured / captured image data storage is repeated until the value of the dynamic range evaluation photographing target unit 11 reaches (255, 255, 255). When the value of the dynamic range evaluation photographing target portion 11 of the photographed image data becomes (255, 255, 255), the process proceeds to step S214, and the photographed image data acquisition process ends.

  Through the processing as described above, captured image data captured with the smallest exposure amount (the RGB value of the dynamic range evaluation imaging target unit 11 is (0, 0, 0)) and the captured image data in order. A plurality of photographed image data photographed with an increased exposure amount, photographed image data photographed with the largest exposure amount (the RGB value of the dynamic range evaluation photographing target portion 11 is (255, 255, 255)), and , Is usually obtained. FIG. 9 is a diagram illustrating an example of captured image data acquired by the captured image data acquisition process of the imaging apparatus evaluation according to the embodiment of the present invention.

  As shown in FIG. 9, for example, the photographic image data D0 photographed at the fastest shutter speed and the photographed image data D1 photographed at the one-step slower shutter speed by the photographed image data acquisition process in the evaluation of the imaging apparatus of the present invention as described above. ,..., Photographic image data Dn photographed at an n-stage slow shutter speed, photographic image data Dm photographed at an m-stage slow shutter speed can be obtained. Here, the relationship of the exposure amount of each photographic image data is (photographed image data D0) <(photographed image data D1) <... <(photographed image data Dn) <... <(photographed image data Dm). is there.

  Next, an information processing apparatus on which the imaging apparatus evaluation program according to the embodiment of the present invention operates will be described. FIG. 10 is a diagram showing a block configuration of the information processing apparatus on which the imaging apparatus evaluation program according to the embodiment of the present invention operates. In FIG. 10, 100 is a network, 201 is a CPU, 202 is a ROM, 203 is a RAM, 204 is a system bus, 205 is an input control unit, 206 is a display output control unit, 207 is a storage medium control unit, and 208 is a network control unit. 209, a keyboard, 210 a mouse, 211 a display panel, 212 a hard disk drive, 213 a flexible disk drive, 214 an optical disk drive, and 215 a media drive.

  FIG. 10 is a block diagram showing an example of the configuration of the personal computer 200, which has the same configuration as a general-purpose personal computer. In the figure, reference numeral 200 denotes an entire personal computer on which software such as a driver operates. The personal computer 200 includes a CPU 201 that executes the driver software of the present invention stored in the ROM 202 or the hard disk drive 212 or supplied by a flexible disk or an optical disk, and summarizes each device connected to the system bus 204. Control.

  A RAM 203 functions as a main memory, work area, and the like for the CPU 201. An input control unit 205 controls an instruction input device from a pointing device such as a keyboard 209 or a mouse 210. A display output control unit 206 controls display on the display panel 211 such as a liquid crystal panel or an EL panel. A storage medium control unit 207 controls access to the hard disk drive 212, the flexible disk drive 213, the optical disk drive 214, and the media drive 215 that store a boot program, various applications, editing files, user files, a network management program, and the like. To do. A network control unit 208 bi-directionally exchanges data with a network printer, another network device, or another personal computer via the network 100. The media drive 215 reads and writes storage media such as an SD memory card, MMC, memory stick, smart media, compact flash, and xD picture card.

  The imaging apparatus evaluation program according to the embodiment of the present invention is stored in, for example, a storage unit such as the hard disk drive 212 of the information processing apparatus configured as described above, and the imaging apparatus evaluation method of the present invention includes: The program can be realized by being executed on the information processing apparatus.

  In the evaluation of the imaging apparatus of the present invention, the captured image data acquired by the processing of FIG. 9 is captured by the personal computer 200 from the imaging apparatus 20 via the flexible disk drive 213, the optical disk drive 214, and the media drive 215. Alternatively, it may be configured to be taken into the personal computer 200 from the imaging apparatus 20 via the network 100, but the captured image data may be taken into the personal computer 200 by other methods.

  Next, processing for evaluating the imaging device 20 (captured image data acquired by the information processing device (personal computer 200) as described above will be described. FIG. 11 is a diagram showing an example of a user interface screen in the imaging device evaluation program according to the embodiment of the present invention. Such user interface screen display is performed on the display panel 211, and the user can execute a desired evaluation process by an input with a pointing device such as the keyboard 209 or the mouse 210.

  In the user interface screen of FIG. 11, captured image data actually captured by the imaging device 20 is displayed in a display portion under “captured image data:”. In “Process Selection:”, a radio button for “dynamic range evaluation”, a radio button for “resolution evaluation”, and a radio button for “false color evaluation” are arranged to select an evaluation process desired by the user. . By setting and selecting these radio buttons, it is possible to cause the imaging apparatus evaluation program to execute an evaluation process as desired by the user.

  Next, a case where the radio button for “dynamic range evaluation” is selected and the dynamic range is evaluated using the imaging apparatus evaluation program will be described. In the following, description will be made based on the situation where (m + 1) captured image data of D0, D1,..., Dn,.

  FIG. 12 is a diagram showing a flowchart of the dynamic range evaluation process in the image pickup apparatus evaluation according to the embodiment of the present invention. In FIG. 12, when the dynamic range evaluation process is started in step S300, 0 is set to n in step S301.

  Next, in step S302, the RGB values (Rn, Gn, Bn) of the portion selected by the user of the dynamic range evaluation photographing target portion 11 of the photographed image data Dn are read out. Here, the location selected by the user refers to a location specified by the user with a pointing device such as the mouse 210 on the captured image data on the user interface screen of FIG. Note that it is not always necessary to make the user specify points on the user interface screen in this way, and the program automatically determines the dynamic range evaluation of the appropriate shooting image data around the shooting target portion 11. You may comprise so that an image may be selected.

  In step S303, the average value of the read RGB values (Rn, Gn, Bn) is calculated. Assuming that the average of the RGB values of the above-mentioned portion of the photographed image data Dn is Mean (RGBn), in step S303, Mean (RGBn) = (Rn + Gn + Bn) / 3 is calculated. In step S303, the luminance is calculated by (luminance) = 0.298912 * Rn + 0.586611 * Gn + 0.114478 * Bn.

  In step S304, it is determined whether n = m. When the determination result of step S304 is NO, the process proceeds to step S306, and when the determination result of step S304 is YES, the process proceeds to step S305. In step S306, which proceeds when the determination result in step S304 is NO, n is incremented by 1, and the process returns to step S302.

  In step S305, which proceeds when the determination result in step S304 is YES, information on the calculated Mean (RGB0), Mean (RGB1),..., Mean (RGBn),. Is output to the display panel 211. Note that the output of such a result may be performed on another device such as a printer. In step S307, the dynamic range evaluation process ends.

  In the present embodiment, information related to the aperture value and shutter speed may be automatically acquired from the Exif data storing the model of the imaging apparatus and the shooting condition information. Information relating to the aperture value and shutter speed may be manually input.

  Next, the output / display process in step S305 will be described. FIG. 13 is a diagram showing a display / output example of the dynamic range evaluation in the imaging apparatus evaluation according to the embodiment of the present invention. Although the present embodiment is configured to output in the form of a graph, it may be output in other forms. The horizontal axis in FIG. 13 is an EV value that is an exposure amount when captured image data is acquired, and the vertical axis is an RGB value of the captured image data. The EV value of the photographed image data can be obtained from the shutter speed and aperture value when the photographed image data is photographed according to a known relational diagram as shown in FIG. FIG. 13 shows an example in which the dynamic range is indicated by a plot of the average value Mean (RGBn) corresponding to the EV value of the captured image data Dn.

  In the evaluation of the dynamic range, an example in which one pixel is averaged has been described, but an average of a plurality of pixels may be used.

  Next, one method for performing dynamic range evaluation of an imaging apparatus using values (evaluation values) will be described. FIG. 14 is a diagram showing a flowchart of the dynamic range value calculation process in the imaging apparatus evaluation according to the embodiment of the present invention. In the process of the flowchart of FIG. 14, Mean (RGBn) calculated in advance is used.

In the flowchart of FIG. 14, when the dynamic range value calculation process is started in step S400, subsequently, in step S401, EV ₀ which is an EV value giving Mean (RGB) = 0 is calculated. EV value EV ₀ giving Mean (RGB) = 0 performs interpolation of each data of Mean (RGB0), Mean (RGB1),..., Mean (RGBn),. Can be obtained. In step S402, EV ₂₅₅ , which is an EV value giving Mean (RGB) = 240, is calculated. The EV value EV ₂₅₅ giving this Mean (RGB) = 255 can also be obtained by performing interpolation as described above. Next, in step S 403, (EV ₂₅₅ −EV ₀ ) is calculated from the EV value EV ₀ and the EV value EV ₂₅₅ obtained in the above step and displayed on the display panel 211. The displayed value of (EV ₂₅₅ -EV ₀ ) is the evaluation value of the dynamic range. A step S404 ends the dynamic range value calculation process.

  In step S403, the evaluation value of the dynamic range can be displayed on an interface screen as shown in FIG. 15, for example. FIG. 15 is a diagram showing a display / output example of the evaluation value of the dynamic range in the imaging apparatus evaluation according to the embodiment of the present invention.

  Next, a case where the “resolution evaluation” radio button is selected and resolution evaluation is performed using the imaging apparatus evaluation program will be described. Here, description will be given based on the situation that (m + 1) of the captured image data of D0, D1,..., Dn,.

  Prior to the resolution evaluation, an optimal one is selected from the photographed image data of D0, D1,..., Dn,. For example, the RGB value is close to 240 for white, and the RGB value is close to 20 for black.

  First, the selection process of such optimum photographed image data will be described. FIG. 16 is a diagram showing a flowchart of evaluation photographic image data selection processing in the imaging apparatus evaluation according to the embodiment of the present invention.

  In FIG. 16, when the selection process of evaluation photographed image data is started in step S500, the process proceeds to step S501, where n = 0 is set.

  Next, in step S502, RGB values (Rwn, Gwn, Bwn) in the white portion of the captured image data Dn are acquired. As such a white portion, the dynamic range evaluation photographing target portion 11 of the imaging device evaluation chart 10 can be used. The selection of the white portion of the captured image data Dn can be automated by an appropriate algorithm, or can be manually set by the user.

In the next step S503, the root mean square value Wn of the difference between the RGB values (Rwn, Gwn, Bwn) and RGB values (240, 240, 240) in the acquired white portion is Wn = √ {(Rwn−240 ) ² + (Gwn−240) ² + (Bwn−240) ² }.

  Next, in step S504, RGB values (Rbn, Gbn, Bbn) at the black portion of the captured image data Dn are acquired. As such a black part, a photographing part of a predetermined portion of the resolution evaluation photographing target part 12 or the false color evaluation photographing target part 13 of the imaging device evaluation chart 10 can be used. The selection of the black portion of the captured image data Dn can be automated by an appropriate algorithm, or can be manually set by the user.

In step S505, the root mean square value Bn of the difference between the acquired RGB values (Rbn, Gbn, Bbn) and RGB values (20, 20, 20) in the black portion is Bn = √ {(Rbn− 20) ² + (Gbn-20) ² + (Bbn-20) ² }.

  In step S506, it is determined whether n = m. When the determination result of step S506 is NO, the process proceeds to step S508, and when the determination result of step S506 is YES, the process proceeds to step S507. In step S508, which proceeds when the determination result in step S506 is NO, n is incremented by 1, and the process returns to step S502.

  In step S507, which proceeds when the determination result in step S506 is YES, W0 + B0, W1 + B1,..., Wn + Bn,. Is selected. The selected photographed image data Dn is used for evaluation of resolution as the optimum photographed image data among D0, D1,..., Dn,. The photographed image data Dn selected here is also used as photographed image data for false color evaluation.

  In step S509, the evaluation photographed image data selection process ends.

  Next, an example of an algorithm for evaluating the resolution with the imaging device evaluation program based on the optimal captured image data for resolution evaluation selected as described above will be described. It should be noted that other commonly used algorithms can be used for resolution evaluation. As such a well-known algorithm, for example, there is an algorithm defined by CIPA DC-003-2003 “Digital Camera Resolution Measurement Method” in the Camera Video Equipment Industry Association Standard.

  FIG. 17 is a diagram showing a flowchart of resolution evaluation processing in the imaging apparatus evaluation according to the embodiment of the present invention, and FIG. 18 extracts a resolution evaluation photographing target part of the imaging apparatus evaluation chart according to the embodiment of the present invention. FIG. 19 is a diagram showing a concept relating to horizontal scanning in the resolution evaluation process.

  In the resolution evaluation process in the imaging apparatus evaluation of the present invention, the imaging part of the resolution evaluation imaging target unit 12 is used. As described above, this resolution evaluation imaging target unit 12 is a pattern in which black and white binary is periodically repeated. It consists of several types from low frequency to high frequency. The concept of “level” is introduced according to the frequency of these patterns, and FIG. 18 shows a level attached according to the frequency of the monochrome pattern. In the present embodiment, the level is shown as 1 to 7, but it goes without saying that multilevel leveling may be applied. Usually, levels from 1 to 20 are often used according to the frequency of such a monochrome pattern.

  In FIG. 17, when the resolution evaluation process is started in step S600, the process proceeds to step S601. In step S601, a chart having the lowest frequency level is selected in the resolution evaluation imaging target unit 12. In the case of this embodiment, it is a level 7 chart. Such chart selection can be automated by a known appropriate algorithm, or can be manually set by a user.

  Next, in step S602, the selected chart is scanned in the horizontal direction to extract a black portion. The horizontal scan in such processing can be performed by calculating RGB values for each pixel along the horizontal direction as shown in the chart of the selected predetermined level.

  Next, in step S603, an interval L between the black portions extracted in step S602 is calculated.

  Next, in step S604, the average value Wim of the RGB values of the intermediate part of the black part (white part in the actual evaluation chart) is calculated.

  Next, in step S605, it is determined whether L ≧ Lo and Wim ≧ Wimo. (Note that the criterion in step S605 may be L ≧ Lo or Wim ≧ Wimo. Such a criterion can be set as appropriate.) Determination in step S605 In short, it is determined whether or not the interval between the black portions can be recognized, and whether or not the white portion between the black portions can be recognized as white.

  If the result of determination in step S605 is YES, it can be determined that the level of the chart being inspected is not yet at the limit resolution, so the process proceeds to step S608, where the frequency level is set as the next chart for inspection. The tallest chart is selected.

  If the result of the determination in step S605 is NO, the level of the chart being inspected can no longer be resolved, so the process proceeds to step S606, where the frequency level is determined from the chart being inspected. The lowest chart is the (limit) resolution.

  In step S609, the resolution evaluation process ends.

  The (limit) resolution obtained by the resolution evaluation process as described above is notified to the user in the form shown in FIG. 20, for example. FIG. 20 is a diagram showing an example of a user interface screen in the resolution evaluation process of the imaging apparatus evaluation program according to the embodiment of the present invention.

  Next, a case where the “false color evaluation” radio button is selected and false image evaluation is performed using the imaging apparatus evaluation program will be described. Here, description will be given based on the situation that (m + 1) of the captured image data of D0, D1,..., Dn,. Further, in the evaluation of false color, an optimum one is selected from the photographed image data of D0, D1,..., Dn,. For such selection processing of optimum photographed image data, the one selected by the flowchart of FIG. 16 (the same one used for resolution evaluation) is used. Hereinafter, the description will be made on the assumption that the optimal captured image data has already been selected.

  FIG. 21 is a diagram showing a flowchart of the false color evaluation process in the imaging apparatus evaluation according to the embodiment of the present invention. In FIG. 21, when the false color evaluation process is started in step S700, in step S701, a predetermined area near the black-and-white boundary of the false color evaluation photographing target portion 13 of the photographed image data is selected. Selection of such a predetermined area can be automated by an appropriate algorithm, or can be manually set by the user. In the case of manual setting by the user, for example, in the user interface screen display shown in FIG. 11, the user can use the pointing device such as the mouse 210 around the black-and-white boundary portion in the false color evaluation shooting target portion 13 of the shot image data. You can take a specified method.

  In step S702, RGB values (R, G, B) of predetermined pixels in the selected predetermined area are acquired. In the next step S703, the difference between the Red channel and the Green channel of the RGB value (RG), the difference between the Green channel and the Blue channel (GB), and the difference between the Blue channel and the Red channel ( The operation of B−R) is executed.

  In step S704, the histogram is incremented by 1 in accordance with the calculated values (RG), (GB), and (BR).

  In step S705, the histogram is displayed on the display panel 211. Such a histogram may be notified to the user by other methods such as printout other than the display on the display panel 211.

  In step S706, it is determined whether or not the above difference value has been calculated for the entire selected predetermined region.

  If the determination result in step S706 is NO, the process proceeds to step S709, and the target is moved to the next pixel in order to calculate a new difference value. If the determination result in step S706 is YES, the process proceeds to step S707.

  Here, the histogram in the false color evaluation process will be described. FIG. 22 shows difference value histograms for (RG), (GB), and (BR) for false color evaluation. FIG. 22A shows the difference value of (RG) on the horizontal axis and the frequency on the vertical axis, and FIG. 22B shows the difference value of (GB) on the horizontal axis. In FIG. 22C, the difference value of (B-R) is taken on the horizontal axis, and the frequency is taken on the vertical axis.

In the present invention, the difference between (R−G), (GB), and (B−R) in the black-and-white boundary region is taken, and the information related to the difference value is used for the evaluation of the false color. If the occurrence of false color is small, the frequency near 0 in the histogram of FIG. 22 increases, and the graph becomes a sharp shape near 0. If the occurrence of false color increases, the graph is horizontally displayed in the histogram of FIG. Expanded shape. By displaying a histogram as shown in FIG. 22 on the display panel 211 in step S705,
Again, it returns to the flowchart of FIG. In step S707, (RG) calculation / display / output of “maximum value”, “minimum value”, “standard deviation” in the difference value histogram, (GB) “maximum value”, “minimum” in the difference value histogram. Calculation, display, and output of “value” and “standard deviation”, and calculation, display, and output of “maximum value”, “minimum value”, and “standard deviation” in the (BR) difference value histogram.

  Here, “maximum value” and “minimum value” mean “maximum value” and “minimum value” of values appearing in the horizontal axis direction of the histogram. (In short, it means the “maximum value” and “minimum value” of the difference value itself.) The “standard deviation” can be obtained by a well-known mathematical method.

  The “maximum value”, “minimum value”, and “standard deviation” of the difference value histogram as described above serve as evaluation indexes for generating false colors. That is, as the “maximum value”, “minimum value”, and “standard deviation” are larger, it becomes a standard for determining that the false color occurrence is higher.

  The “maximum value”, “minimum value”, and “standard deviation” in step S707 are displayed on the display panel 211, but these are output by other methods other than the display on the display panel 211, such as printout. You may make it alert | report to. FIG. 23 is a diagram showing an example of a user interface screen when “maximum value”, “minimum value”, and “standard deviation” are displayed on the display panel 211.

  In the next step S708, scoring is performed with reference to the score assignment chart. Here, the score provision chart will be described. FIG. 24 is a diagram showing a score assignment chart in the false color evaluation of the imaging apparatus evaluation program according to the embodiment of the present invention.

  In the false color evaluation chart of FIG. 24, the horizontal axis indicates “standard deviation”, and the vertical axis indicates a larger value among “maximum value” and “minimum value”. In addition, the scoring chart is provided with dotted lines for scoring as shown in FIG. A large value among the “standard deviation”, the “maximum value”, and the “minimum value” obtained in step S707 is plotted in the scoring chart, and scoring is performed according to which region the plot belongs to. . For example, when a large value among “standard deviation”, “maximum value”, and “minimum value” is the plot shown in FIG. 24A, the score is 80 points, and “standard deviation”, “maximum value”, In the case where the larger value among the “minimum values” is the plot shown in FIG. 24B, the score is 40 points, and the larger value among “standard deviation”, “maximum value”, and “minimum value” is the one in FIG. In the case of the plot shown in C, scoring is performed with a score of 20 points.

  FIG. 25 is a diagram showing an example of a user interface screen for displaying a score for false color evaluation in the imaging device evaluation program according to the embodiment of the present invention. In the example of FIG. 25, the false color evaluation scoring is performed using the Red-Green difference, but all the difference values are averaged by an appropriate method, and the averaged value is scored. May be. Alternatively, it may be set so that false color evaluation is scored by each difference of (R−G), (GB), and (B−R), and only the average value is notified to the user.

  In this embodiment, the scoring chart as described above is used for scoring evaluation regarding false color generation, but false color evaluation is performed using other methods. Of course.

  In step S710, the false color evaluation process ends.

  According to the imaging apparatus evaluation chart, the imaging apparatus evaluation method, and the imaging apparatus evaluation program according to the embodiment of the present invention as described above, the “dynamic range”, “resolution”, and “false color” of the imaging apparatus are set. At the same time, it can be easily evaluated.

It is a figure which shows the imaging device evaluation chart which concerns on embodiment of this invention. It is a figure which extracts and shows the false color evaluation imaging | photography target part of the imaging device evaluation chart which concerns on embodiment of this invention. It is a figure which shows the other example of the false color evaluation imaging | photography target part of the imaging device evaluation chart which concerns on embodiment of this invention. It is a figure which shows the other example of the false color evaluation imaging | photography target part of the imaging device evaluation chart which concerns on embodiment of this invention. It is a figure which shows the imaging | photography method of the imaging device evaluation chart which concerns on embodiment of this invention. It is a figure which shows the imaging | photography method of the imaging device evaluation chart which concerns on embodiment of this invention. It is a figure which shows the outline of the flow of evaluation of the imaging device which concerns on embodiment of this invention. It is a figure which shows the flowchart of the picked-up image data acquisition process in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the example of the picked-up image data acquired by the picked-up image data acquisition process of imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the block configuration of the information processing apparatus with which the imaging device evaluation program which concerns on embodiment of this invention operate | moves. It is a figure which shows the example of a user interface screen in the imaging device evaluation program which concerns on embodiment of this invention. It is a figure which shows the flowchart of the dynamic range evaluation process in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the example of a display and output of the dynamic range evaluation in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the flowchart of the dynamic range value calculation process in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the example of a display and output of the evaluation value of a dynamic range in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the flowchart of the selection process of the picked-up image data for evaluation in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the flowchart of the resolution evaluation process in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which extracts and shows the resolution evaluation imaging | photography target part of the imaging device evaluation chart which concerns on embodiment of this invention. It is a figure which shows the concept concerning the scanning of the horizontal direction in a resolution evaluation process. It is a figure which shows the example of a user interface screen in the resolution evaluation process of the imaging device evaluation program which concerns on embodiment of this invention. It is a figure which shows the flowchart of the false color evaluation process in the imaging device evaluation which concerns on embodiment of this invention. It is a figure which shows the (RG), (GB), (BR) difference value histogram for false color evaluation. It is a figure which shows the user interface screen example of "maximum value", "minimum value", and "standard deviation" for false color evaluation of the imaging device evaluation program which concerns on embodiment of this invention. It is a figure which shows the chart for score provision in the false color evaluation of the imaging device evaluation program which concerns on embodiment of this invention. It is a figure which shows the example of a user interface screen of the score display for false color evaluation in the imaging device evaluation program which concerns on embodiment of this invention. FIG. 4 is a relationship diagram of shutter speed, aperture value, and EV value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Chart for imaging device evaluation, 11 ... Dynamic range evaluation imaging target part, 12 ... Resolution evaluation imaging target part, 13 ... False color evaluation imaging target part, 20 ... Imaging apparatus, 30 ... Wall surface, 40 ... Light source, 50 ... Tripod, 100 ... Network, 201 ... CPU, 202 ... ROM, 203 ... RAM, 204 ... System bus, 205 ..Input control unit, 206 ... Display output control unit, 207 ... Storage medium control unit, 208 ... Network control unit, 209 ... Keyboard, 210 ... Mouse, 211 ... Display panel 212, hard disk drive, 213, flexible disk drive, 214, optical disk drive, 215, media drive

Claims (3)

The dynamic range evaluation photographing target part consisting of a white complete diffusing surface with a reflectance of 1 in all wavelength regions, and a plurality of patterns in which a white band part and a black band part are alternately repeated at different intervals, and have a low frequency For evaluation of an imaging device having at least a resolution evaluation photographing target part composed of several types from a pattern to a high pattern, and a false color evaluation photographing target part consisting of a white part and a black part at various angles with respect to the vertical direction Taking a chart with an imaging device, obtaining a photographed image data with the largest exposure amount from a photographed image data with the smallest exposure amount, while reducing the shutter speed from the fastest shutter speed of the imaging device;
Dynamic range evaluation of photographed image data The process of displaying and outputting the luminance value obtained from the average value or RGB value of the photographing target portion and the EV value when the photographed image data is photographed,
Of the photographed image data, a process of selecting photographed image data for resolution evaluation / false color evaluation for RGB with a RGB value close to 240 for black and a RGB value close to 20 for black (however, the RGB value ranges from 0 to 255) Up to
Resolution evaluation of captured image data for resolution evaluation / false color evaluation Whether or not the distance between black portions can be recognized for several types of patterns from low frequency patterns to high patterns in the target area, white portion between black portions Determining whether or not can be recognized as white, and notifying a level corresponding to a pattern whose resolution is limited;
(RG) Histogram, which is the difference between the Red channel of the RGB value and the Green channel, and the difference between the Green channel and the Blue channel (GB). Histogram, and (BR) histogram which is the difference between Blue channel and Red channel, and (RG) calculation / display of “maximum value”, “minimum value”, “standard deviation” in difference value histogram Output, (GB) Calculation / display / output of “maximum value”, “minimum value”, “standard deviation” in difference value histogram, (BR) “maximum value”, “minimum value” in difference value histogram And a process of calculating, displaying, and outputting “standard deviation” . 2. The method for evaluating an imaging apparatus according to claim 1, wherein the completely diffusing surface is a coated surface of magnesium oxide. 2. The imaging apparatus evaluation method according to claim 1, wherein the completely diffusing surface is a barium sulfate coating surface.

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