JP4385776B2 - Display performance measuring apparatus and method - Google Patents

Description

  The present invention relates to a display performance measuring apparatus and method for measuring display performance particularly related to sharpness as display performance in a display device such as a CRT display device or a liquid crystal display device.

  Sharpness is one of the important measures for evaluating the performance of display devices such as CRT display devices, liquid crystal display devices, and plasma display devices. Sharpness is a measure that represents the sharpness of an image, such as the clarity of the border of an image and the sharpness of a fine part of the image. Most important in determining the degree of achievement.

  Unlike a physical quantity such as brightness or resolution, sharpness is a scale that includes human psychological elements, and therefore, in general, the evaluation is often left to sensitive judgment by the human eye.

  Non-Patent Document 1 below describes an example in which the sharpness is quantified by the following mathematical formula.

Each symbol in the above formula indicates the following contents.
S ... Subjective sharpness;
ν ... spatial frequency;
R (ν): MTF (modulation transfer function) of image transmission / display system;
E (ν): MTF of visual system;
n: an integer of 1 or 2;

The Institute of Television Engineers of Japan, “Television and Image Information Engineering Handbook”, first edition, Ohm Co., Ltd., November 30, 1990, p. 58

  However, it is difficult to obtain accurate and reliable evaluation results because it is inevitable that the conventional evaluation of subjective sharpness will produce different results for each evaluator. There is a disadvantage of being.

  In addition, with the subjective evaluation method, it is difficult to absolutely evaluate the sharpness, and a relative comparison must be made. For this reason, it is necessary to carry out the comparison after bringing the display devices to be compared to the same place and adjusting the same conditions, which is disadvantageous.

  On the other hand, in the method for quantifying the sharpness based on the above-described equation (1), it is necessary to measure the MTF of the image transmission / display system and the MTF of the visual system, and therefore the measurement procedure and the processing are complicated. There are disadvantages.

  The present invention has been made in view of such circumstances, and the object thereof is a display performance measuring device capable of measuring objective performance of a display device related to the sharpness of a display image while having a simple configuration and procedure. And providing that method.

A display performance measuring apparatus according to a first invention that achieves the above object is a display performance measuring apparatus that measures the performance of a display device relating to the sharpness of a display image, and the maximum value and the frequency of the luminance change rate are different from each other. A plurality of periodic image pattern image signals, and the luminance level set for a series of pixels constituting the display image to be measured changes to a predetermined periodic wave shape along the series of pixels. Generating an image signal having a sine wave component and supplying the image signal to a display device to be measured, an image pickup unit for picking up an image displayed on the measurement target, and each image picked up by the image pickup unit and luminance change rate acquisition unit that acquires between two positions of the pixels adjacent to each other the rate of change of luminance in the periodic image pattern, a predetermined frequency which is acquired by the luminance change rate acquisition unit Okeru a rate of change in luminance, a rate of change in position of the pixel such as the value of the derivative of the predetermined said sinusoidal function of frequency included in the component of the periodic image pattern is maximum, the The coefficient corresponding to the predetermined frequency included in the coefficient term in the derivative is compared while increasing the predetermined frequency, and as a result of the comparison, an increase in the rate of change in luminance corresponds to the predetermined frequency. An evaluation value acquisition unit that evaluates that the higher the predetermined frequency when the increase in the coefficient to be performed becomes higher, the better the sharpness.

According to the first aspect of the present invention, the display device to be measured has a plurality of brightness change rate maximum values and periods different from each other according to the image signal having a sine wave component generated in the image signal generation unit. A periodic image pattern is displayed. Each periodic image pattern is captured by the imaging unit, and the luminance change rate in the captured periodic image pattern is acquired by the luminance change rate acquisition unit between two positions of adjacent pixels. .
The evaluation value acquisition unit is a luminance change rate at a predetermined frequency acquired by the luminance change rate acquisition unit, and is a derivative value of a function of a sine wave of a predetermined frequency included in the component of the periodic image pattern The rate of change at the pixel position at which the maximum value is maximized and the coefficient corresponding to the predetermined frequency included in the coefficient term in the derivative are compared while increasing the predetermined frequency. as the predetermined frequency is high when the increased rate is no longer able to follow the increase in the coefficient corresponding to the predetermined frequency, it is evaluated as the sharpness is good.

Preferably, the luminance change rate acquisition unit acquires a maximum value of the luminance change rate in each of the periodic image patterns captured by the imaging unit .

The first invention preferably includes a normalization processing unit that normalizes the luminance of the image captured by the imaging unit based on a predetermined reference luminance related to the maximum luminance of the measurement target, The luminance change rate acquisition unit acquires a maximum value of the luminance change rate in the captured image of the periodic image pattern normalized by the normalization processing unit.
Thereby, a measurement result that makes it possible to objectively compare display performance related to sharpness is obtained even between display devices having different maximum luminances.

In this case, the image signal generation unit may generate an image signal of the maximum luminance image in the measurement target display device, and the normalization processing unit may calculate the luminance of the maximum luminance image captured by the imaging unit. The reference luminance may be acquired according to the average.
As a result, an appropriate reference luminance corresponding to the maximum luminance can be obtained for each measurement object, so that the measurement accuracy is improved.

Further, the evaluation value acquiring unit, from among the plurality of periodic image pattern to identify a periodic image pattern maximum value of the rate of change of the luminance acquired at the luminance change ratio acquisition unit is maximized, the It is evaluated that the sharpness is better as the maximum value of the luminance change rate acquired corresponding to the specified periodic image pattern is larger .
Thereby, the performance relating to the sharpness of the display device to be measured is quantitatively evaluated.

The display performance measuring method of the second invention that achieves the above object is an image signal of a plurality of periodic image patterns each having a different maximum value and cycle of the luminance change rate, and constitutes the display image to be measured An image signal having a sine wave component whose magnitude of luminance set for a series of pixels changes to a predetermined periodic wave shape along the series of pixels is supplied to the display device to be measured, and the image A first step of capturing an image displayed on the measurement object according to a signal, and a change rate of luminance in each of the periodic image patterns captured in the first step of the pixels adjacent to each other a second step of obtaining between two positions, a luminance change ratio at a predetermined frequency which is acquired in the second step, included in components of the periodic image pattern A rate of change in position of the predetermined said sinusoidal said pixels as the value of the derivative is the maximum of a function of frequency, and a coefficient corresponding to the predetermined frequency included in the coefficient term in the derivative The comparison is made while increasing the predetermined frequency, and as a result of the comparison, the higher the predetermined frequency when the increase in the change rate of the luminance becomes unable to follow the increase in the coefficient corresponding to the predetermined frequency, And a third step of evaluating that the sharpness is good.

According to the second aspect of the invention, in the first step, an image signal having a sine wave component of a plurality of periodic image patterns having different maximum values and periods of luminance change is supplied to the display device to be measured. Is done. Then, an image displayed on the measurement object is captured in accordance with the image signal. In the second step, the luminance change rate in each of the periodic image patterns imaged in the first step is acquired between two positions of adjacent pixels .
Further, in the third step, the luminance change rate at the predetermined frequency obtained in the second step is a derivative of a function of a sine wave having a predetermined frequency included in the component of the periodic image pattern. a rate of change in position of the pixel whose value is maximum, and a coefficient corresponding to a predetermined frequency included in the coefficient term in the derivative, compared with increasing the predetermined frequency, the comparison result, the luminance It is evaluated that the sharpness is better as the predetermined frequency is higher when the increase in the change rate cannot follow the increase in the coefficient corresponding to the predetermined frequency.

Preferably, in the second step, the maximum value of the luminance change rate in each of the periodic image patterns captured in the first step is acquired.

In the second invention, preferably, the luminance of the periodic image pattern captured in the first step is normalized based on a predetermined reference luminance related to the maximum luminance in the display device to be measured. a fourth step, in the second step, to obtain the maximum value of the rate of change of brightness in the fourth normalized captured image of the periodic image pattern in step.
Thereby, a measurement result that makes it possible to objectively compare display performance related to sharpness is obtained even between display devices having different maximum luminances.

  According to the present invention, it is possible to measure the objective performance of a display device related to the sharpness of a display image with a simple configuration and procedure.

  Hereinafter, two embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a diagram showing an example of the configuration of a display performance measuring apparatus 10 according to the first embodiment of the present invention.

A display performance measuring apparatus 10 illustrated in FIG. 1 includes an image signal generation unit 11, an imaging unit 12, a data storage unit 13, a normalization processing unit 14, and a maximum luminance change rate acquisition unit 15.
In the above configuration, the image signal generation unit 11 is an embodiment of the image signal generation unit of the present invention.
The imaging unit 12 is an embodiment of the imaging unit of the present invention.
The normalization processing unit 14 is an embodiment of the normalization processing unit of the present invention.
The maximum luminance change rate acquisition unit 15 is an embodiment of the maximum luminance change rate acquisition unit of the present invention.

The image signal generation unit 11 generates an image signal of a predetermined image used for measurement and supplies it to the display device 16 to be measured.
That is, as a measurement image for obtaining a reference luminance, which will be described later, first, an image signal of an image with the maximum luminance (that is, a white image as a whole) on the display device 16 is generated.
Next, image signals of a plurality of periodic image patterns having different periods are generated and supplied to the display device 16. This periodic image pattern is, for example, an image pattern in which the luminance on the image changes to a periodic wave shape such as a sine wave.

However, the periodic image pattern described here is a virtual image pattern set by the image signal of the image signal generation unit 11 with respect to the display device 16, and an image actually displayed on the display device 16 is Depending on the display performance such as the sharpness of the display device 16, the image is different from this.
That is, the image signal generation unit 11 changes the luminance magnitude set for a series of pixels constituting the display image of the display device 16 into a periodic wave shape such as a sine wave along the series of pixels. A simple image signal is generated. The actual display image corresponding to this image signal is an image different from the setting according to the display performance such as sharpness.

  The maximum brightness image and the plurality of periodic image patterns described above may be displayed in an arbitrary display area of the display device 16, but preferably these images are displayed while being switched to the same display area. That is, the image signal generation unit 11 displays the above-described image having the maximum luminance and a plurality of periodic image patterns in the same display area of the display device 16 while sequentially switching. This makes it possible to accurately measure display performance related to sharpness for a specific display area of the display device 16.

  The imaging unit 12 images a display image of the display device 16 using an imaging element such as a CCD camera or a CMOS camera, and outputs the imaging result as digital captured image data.

  The data storage unit 13 stores captured image data output from the imaging unit 12.

The normalization processing unit 14 performs normalization processing of the brightness of the captured image data stored in the data storage unit 13.
That is, as a process for obtaining the reference brightness, first, the captured image data of the above-described maximum brightness image stored in the data storage unit 13 is read, the average brightness of the captured images is calculated, and this is acquired as the reference brightness R. .
Next, the captured image data of the periodic image pattern stored in the data storage unit 13 is read, and the luminance B of each pixel of the captured image is normalized by the following equation, for example.

[Equation 2]
Bn = 100 × B / R (2)

  The normalized luminance Bn shown in Expression (2) is “100” when it is equal to the reference luminance R, and has a value of “0” to “100” in most pixels.

The maximum luminance change rate acquisition unit 15 acquires the maximum value of the luminance change rate in the captured image of the periodic image pattern normalized by the normalization processing unit 14.
The luminance change rate indicates, for example, a luminance difference between adjacent pixels. That is, when the luminance Ba of the pixel Pa and the luminance Bb of the pixel Pb adjacent thereto are given, the luminance change rate X between the pixels is given by the following equation, for example.

[Equation 3]
X = | Bb−Ba | (3)

  The maximum luminance change rate acquisition unit 15 acquires the maximum value of such a luminance change rate for each of captured images of a plurality of periodic image patterns having different periods.

  Next, the schematic operation of the display performance measuring apparatus 10 described above will be described with reference to the flowchart shown in FIG.

  First, the image signal generation unit 11 generates an image signal of an image with the maximum luminance on the display device 16 and displays this image in a display area where the display device 16 performs measurement (step ST1).

FIG. 3A shows an example of an image with the maximum luminance displayed on the display device 16.
FIG. 3D shows an example of a set value of luminance on the line SS ′ in FIG. However, the vertical axis in FIG. 3D represents the luminance, and the horizontal axis represents the position on the display screen along the line SS ′.
As shown in FIG. 3D, the image when the luminance setting value is maximized is generally a white image as shown in FIG.

  The imaging unit 12 captures the image with the maximum luminance displayed on the display device 16, and writes the captured image data in the data storage unit 13 (step ST2). The normalization processing unit 13 reads the captured image data from the data storage unit 13, calculates the average luminance of the captured image, and acquires this as the reference luminance R for normalization processing (step ST3).

  When the reference luminance R is obtained, the image signal generation unit 11 next generates an image signal of a periodic image pattern having a predetermined period, and displays this image in the display area where the display device 16 performs measurement ( Step ST4).

FIGS. 3B and 3C show examples of periodic image patterns displayed on the display device 16.
FIGS. 3E and 3F show examples of set values of luminance on the line SS ′ in FIGS. 3B and 3C, respectively. The meanings of the vertical axis and the horizontal axis are the same as those in FIG.
As can be seen from the figure, the image patterns in FIGS. 3C and 3F have a shorter period (that is, a higher frequency) than the image patterns in FIGS. 3B and 3E.

  In addition, according to the examples of FIGS. 3E and 3F, the luminance setting values for a series of pixels that are continuous in the horizontal direction change in a sine wave shape along the series of pixels. When such a luminance change pattern is set in the display device 16 by the image signal generation unit 11, vertical stripe image patterns as shown in FIGS. 3B and 3C appear in the display image.

  The imaging unit 12 captures such a periodic image pattern displayed on the display device 16, and writes the captured image data in the data storage unit 13 (step ST5). The averaging processing unit 14 reads the captured image data from the data storage unit 13, and performs normalization processing of the captured image using the reference luminance acquired in step ST3 (step ST6). For example, when a normalization process as shown in Expression (2) is performed, the luminance of each pixel is a value that is included in the numerical value range from “0” to “100”.

  The maximum luminance change rate acquisition unit 15 obtains the luminance change rate in the captured image of the normalized periodic image pattern, and acquires the maximum value (step ST7).

FIG. 4 is a diagram illustrating an example of a luminance change in a portion corresponding to the line SS ′ in FIG. 3 in the captured image of the normalized periodic image pattern.
In the captured image showing the luminance change as shown in this figure, the maximum luminance change rate acquisition unit 15 calculates the luminance change rate X between adjacent pixels based on, for example, the equation (3). Then, the maximum value of the change rate X in the display area to be measured is obtained.

The processes in steps ST4 to ST7 described above are repeatedly executed for each of a plurality of periodic image patterns having different periods (frequencies) (steps ST8 and ST9).
As described above, data representing the relationship between the frequency of the periodic image pattern and the maximum value of the luminance change rate is obtained as a measurement result of the sharpness performance of the display device 16.

  FIG. 5 is a diagram illustrating the relationship between the maximum value of the luminance change rate and the frequency of the sine wave when a sine wave image pattern is used.

  The sine wave signal y (x) and its derivative y '(x) are represented by the following equations, where the signal amplitude is ‘A’ and the frequency is ‘f’.

y = A sin (2πfx) (3);
y ′ = 2πAf cos (2πfx) (4);

As can be seen from the equation (4), the maximum value “2πAf” of the rate of change of the sine wave signal increases in proportion to the frequency f. Therefore, the maximum value of the luminance change rate in the actual display image increases as the frequency increases, as shown in FIG.
However, when the output image of the display device 16 cannot follow the input image signal due to the limit of the sharpness performance of the display device 16, the maximum value of the rate of change in luminance becomes smaller after a certain frequency Fp as a peak. It changes to become.

  Therefore, it is possible to objectively grasp the sharpness performance of the display device 16 from the measurement result as shown in FIG. 5 showing the relationship between the maximum value of the luminance change rate and the frequency of the image pattern. That is, it can be seen that the higher the frequency at which the maximum value of the luminance change rate reaches the peak and the higher the peak value, the higher the sharpness performance of the display device 16.

As described above, according to the display performance measuring device 10 according to the present embodiment, the display device 16 to be measured has a plurality of different periods respectively according to the image signal generated by the image signal generating unit 11. A periodic image pattern is displayed. The image patterns are respectively captured by the image capturing unit 12, and the maximum value of the luminance change rate in the captured image pattern is acquired by the maximum luminance change rate acquiring unit 15.
As described above, the periodical value displayed on the display device 16 as an objective measurement result representing the performance of the display device 16 regarding the sharpness is a simple process of obtaining the maximum value of the luminance change rate in the captured image. It is possible to obtain the relationship between each period (frequency) of a simple image pattern and the maximum value of the luminance change rate in the actual display image. Therefore, it is possible to objectively grasp the performance of sharpness, which is an important evaluation scale of the display device, and it is possible to eliminate measurement uncertainty in the conventional subjective method, and to improve the image quality of the display device. It is possible to efficiently perform comparative evaluation and confirmation of the degree of design achievement of the display device without depending on human hands. In addition, the procedure and processing content required for measurement can be simplified as compared with the conventional method that requires MTF measurement.

Further, according to the display performance measuring apparatus 10, the luminance of the image captured by the imaging unit 12 is normalized by the normalizing unit 14 based on the reference luminance related to the maximum luminance in the display device 16 to be measured. The Then, the maximum value of the luminance change rate in the normalized captured image is acquired by the maximum luminance change rate acquisition unit 15.
For this reason, it is possible to objectively compare the display performance related to the sharpness even between display devices having different maximum brightness (for example, display devices of different models).

Moreover, according to the display performance measuring apparatus 10, an appropriate reference luminance is acquired for each display apparatus to be measured, and used for normalization processing of captured images. That is, at the beginning of the measurement, the image signal generation unit 11 generates an image signal of an image having the maximum luminance on the display device 16 and supplies the image signal to the display device 16. In the normalization processing unit 14, the reference luminance is acquired according to the average luminance in the captured image of the maximum luminance image displayed on the display device 16.
As described above, an appropriate reference luminance corresponding to the maximum luminance is acquired for each measurement target, and the captured image is normalized based on the reference luminance, so that the measurement accuracy can be improved.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
In the second embodiment, a quantitative evaluation unit for display performance related to sharpness is provided.

FIG. 6 is a diagram showing an example of the configuration of a display performance measuring apparatus 10A according to the second embodiment of the present invention.
The display performance measuring apparatus 10A illustrated in FIG. 6 has the same configuration as the display performance measuring apparatus 10 already described (an image signal generation unit 11, an imaging unit 12, a data storage unit 13, a normalization processing unit 14, a maximum luminance change rate. And an evaluation value acquisition unit 17 which is an embodiment of the evaluation value acquisition unit.

FIG. 7 is a flowchart for explaining the operation of the display performance measuring apparatus 10A shown in FIG.
The difference from the flowchart shown in FIG. 2 is that, after the measurement result as shown in FIG. 5 showing the relationship between the period of the image pattern and the maximum value of the luminance change rate is obtained, the sharpness is determined based on this measurement result. The process (step ST10) of the evaluation value acquisition unit 17 that acquires the evaluation value of the related display performance is added.

  The evaluation value acquisition unit 17 specifies an image pattern in which the maximum value of the luminance change rate acquired by the maximum luminance change rate acquisition unit 15 is the largest, and the cycle of the specified image pattern (for example, the frequency Fp in FIG. 5). Or the evaluation value of the display performance related to the sharpness is acquired based on one or both of the maximum values of the luminance change rate (for example, the change rate Sp in FIG. 5) acquired corresponding to the specified image pattern. .

  For example, the evaluation value acquisition unit 17 obtains the frequency Fp and the change rate Sp at the peak from the measurement result as shown in the example of FIG. 5, and acquires one of these values as the evaluation value of the sharpness performance. To do.

Alternatively, the evaluation value acquisition unit 17 may calculate the evaluation value of the sharpness performance based on a predetermined sharpness performance evaluation function including the frequency Fp and the change rate Sp as variables.
Alternatively, a data table in which evaluation values of sharpness performance when the frequency Fp and the change rate Sp are included in predetermined ranges is prepared in advance, and measurement is performed by referring to the data table. You may acquire an evaluation value for every object.

  That is, the evaluation value acquisition unit 17 performs a process of acquiring the evaluation value of the sharpness performance based on at least the frequency Fp and / or the change rate Sp. The evaluation value may be a specific numerical value or a rank indicating the sharpness performance.

As described above, according to the display performance measuring apparatus 10A according to the present embodiment, the period of the periodic image pattern in which the maximum value of the luminance change rate acquired by the maximum luminance change rate acquisition unit 15 is the largest, or Based on one or both of the maximum luminance change rates acquired corresponding to the periodic image pattern, an evaluation value of display performance related to sharpness is acquired.
Therefore, it becomes possible to quantitatively evaluate the sharpness performance, and it becomes possible to more clearly grasp the comparative evaluation of the image quality of the display device and the degree of design achievement of the display device. In addition, since sharpness performance can be automatically and efficiently evaluated, a large amount of display devices can be handled in, for example, shipping inspection.

  The above-described embodiment is a preferable specific example of the present invention, and various technically preferable limitations are given. However, the present invention is not limited to this embodiment, and for example, as described below. There are various variations.

  In the above-described embodiment, an example in which images for measurement are sequentially switched and displayed on the display device 16 is shown. However, the present invention is not limited to this. For example, these images are simultaneously displayed in different display areas of the display device 16. May be measured. In this case, the measurement accuracy of the display performance related to the sharpness is slightly lowered, but the measurement procedure can be simplified.

  In the above-described embodiment, the reference luminance is calculated based on the captured image data of the image having the maximum luminance, and the normalization process is performed using the calculated reference luminance. However, the present invention is not limited to this. For example, when the variation of the maximum luminance in the display device to be measured is relatively small, normalization processing may be performed using data of a predetermined reference luminance. Thereby, steps ST1 and ST2 in the flowcharts of FIG. 2 and FIG. 7 can be omitted, so that the measurement procedure can be further simplified. Furthermore, the normalization process can be omitted when the maximum luminance is substantially equal, such as when the display devices to be compared are of the same model.

In the above-described embodiment, an example in which a sinusoidal image pattern is used as the measurement image pattern is shown. However, the present invention is not limited thereto, and various periodic wave image patterns such as a triangular wave may be used. .
Furthermore, in the present invention, the image pattern used for measurement is not limited to a periodic image pattern. In other words, at least a plurality of image patterns having different maximum values of luminance change rates can be used as measurement image patterns.

  The display device to be measured in the present invention is not limited to a video display device such as a CRT display device or a liquid crystal display device, and includes, for example, a printer device that prints an image on paper or the like. In this case, it is possible to measure the display performance (that is, the printing performance) related to the sharpness of the printer device by picking up an image of the printing result with the imaging device 12 and processing it in the same manner.

It is a figure which shows an example of a structure of the display performance measuring apparatus which concerns on the 1st Embodiment of this invention. 3 is a flowchart for explaining the operation of the display performance measuring apparatus shown in FIG. It is the figure which illustrated the image for a measurement displayed on a display apparatus, and the setting value of the brightness | luminance. It is the figure which illustrated an example of the change of the brightness | luminance in the imaged image. It is the figure which illustrated the relationship between the maximum value of the change rate of a brightness | luminance, and the frequency of a periodic image pattern. It is a figure which shows an example of a structure of the display performance measuring apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the display performance measuring apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10A ... Display performance measuring apparatus, 11 ... Image signal production | generation part, 12 ... Imaging part, 13 ... Data storage part, 14 ... Normalization process part, 15 ... Maximum luminance change rate acquisition part, 16 ... Display apparatus, 17 ... Evaluation value acquisition unit

Claims (8)

A display performance measuring device for measuring the performance of a display device related to the sharpness of a display image,
The image signal of a plurality of periodic image patterns having different maximum values and frequencies of luminance change, and the magnitude of the luminance set for a series of pixels constituting the display image to be measured is the series. An image signal generation unit that generates an image signal having a sine wave component that changes into a predetermined periodic wave shape along the pixel of the pixel, and supplies the image signal to a display device to be measured;
An imaging unit that captures an image displayed on the measurement target;
A luminance change rate acquisition unit for acquiring a luminance change rate in each of the periodic image patterns imaged by the imaging unit between two positions of the pixels adjacent to each other ;
The luminance change rate at a predetermined frequency acquired by the luminance change rate acquisition unit, and the value of the derivative of the function of the sine wave of the predetermined frequency included in the component of the periodic image pattern is maximum. The rate of change at the position of the pixel is compared with a coefficient corresponding to the predetermined frequency included in the coefficient term in the derivative while increasing the predetermined frequency,
As a result of the comparison, the evaluation value acquisition unit evaluates that the higher the predetermined frequency is, the better the sharpness is when the increase in the luminance change rate cannot follow the increase in the coefficient corresponding to the predetermined frequency. And a display performance measuring device. The display performance measuring apparatus according to claim 1, wherein the luminance change rate acquisition unit acquires a maximum value of a luminance change rate in each of the periodic image patterns captured by the imaging unit. A normalization processing unit that normalizes the luminance of the image captured by the imaging unit based on a predetermined reference luminance related to the maximum luminance of the measurement target;
The luminance change rate acquisition unit acquires the maximum value of the luminance change rate in the captured image of the periodic image pattern normalized by the normalization processing unit,
The display performance measuring apparatus according to claim 2. The image signal generation unit generates an image signal of an image having the maximum luminance in the measurement target,
The normalization processing unit obtains the reference luminance according to an average of luminance in the image of the maximum luminance imaged by the imaging unit.
The display performance measuring apparatus according to claim 3 . The evaluation value acquisition unit identifies a periodic image pattern in which the maximum value of the luminance change rate acquired by the luminance change rate acquisition unit is the largest among the plurality of periodic image patterns. The display performance measuring apparatus according to claim 2, wherein the sharpness is better as the maximum value of the change rate of the luminance acquired corresponding to the periodic image pattern is larger. A display performance measuring method for measuring the performance of a display device relating to the sharpness of a display image,
The image signal of a plurality of periodic image patterns having different maximum values and periods of luminance change, and the magnitude of the luminance set for a series of pixels constituting the display image to be measured is the series. An image signal having a sine wave component that changes into a predetermined periodic wave shape along the pixel is supplied to a display device to be measured, and an image displayed on the measurement target is captured in accordance with the image signal. 1 step,
A second step of acquiring a rate of change in luminance in each of the periodic image patterns imaged in the first step between two positions of the pixels adjacent to each other ;
The luminance change rate at the predetermined frequency acquired in the second step, and the derivative value of the function of the sine wave of the predetermined frequency included in the component of the periodic image pattern is maximized. The rate of change at the pixel position is compared with a coefficient corresponding to the predetermined frequency included in the coefficient term in the derivative while increasing the predetermined frequency,
As a result of the comparison, a third step of evaluating that the higher the predetermined frequency when the increase in the luminance change rate cannot follow the increase in the coefficient corresponding to the predetermined frequency, the better the sharpness. A display performance measuring method comprising: The display performance measuring method according to claim 6 , wherein in the second step, a maximum value of a luminance change rate in each of the periodic image patterns captured in the first step is acquired. A fourth step of normalizing the luminance of the periodic image pattern imaged in the first step based on a predetermined reference luminance related to the maximum luminance of the measurement object;
In the second step, the maximum value of the luminance change rate in the captured image of the periodic image pattern normalized in the fourth step is acquired.
The display performance measuring method according to claim 7 .

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