JP2013098900A - Display device evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device evaluation method capable of properly evaluating the display characteristics of a display device.SOLUTION: The display device evaluation method obtains the measured value of a color difference with respect to a display device to be evaluated which displays a predetermined color reference image preset using a visibility evaluation result. Using the subjective evaluation result of the color difference about the display device which displays the color reference image and a color comparison image in contrast, the method obtains the detection limit value of the color difference about the display device, considering visibility depending on colors. The method obtains an evaluation parameter using the measured value of the color difference and the detection limit value of the color difference, and performs evaluation relating to the display characteristic of the display device using the evaluation parameter.

Description

  The present disclosure relates to a method for evaluating color reproduction characteristics or the like in a display device that displays a color image or the like.

  Various evaluation methods for display characteristics of display devices using CRT (Cathode Ray Tube), LCD (Liquid Crystal Display), PDP (Plasma Display Panel), organic EL (Electro Luminescence), etc. Has been proposed (see, for example, Patent Document 1).

JP 2011-135216 A

  In Patent Document 1, an objective display characteristic evaluation that matches a human sense is realized by performing an evaluation in consideration of a color-dependent visual sensitivity (visibility with respect to a color change). However, further improvement is desired for the evaluation method of display characteristics such as color reproduction characteristics.

  The present disclosure has been made in view of such problems, and an object of the present disclosure is to provide a display device evaluation method capable of appropriately evaluating display characteristics in a display device.

  The display device evaluation method according to the present disclosure obtains a color difference measurement value for a display device to be evaluated that displays a predetermined color reference image that is set in advance using a visual evaluation result. Using the subjective evaluation result of the color difference for the display device that displays the comparison image in contrast, the color difference detection limit value for the display device is calculated in consideration of the color-dependent visual sensitivity, and the measured value of the color difference An evaluation parameter is obtained using the color difference detection limit value, and the evaluation of the display characteristics of the display device is performed using this evaluation parameter.

  In the display device evaluation method of the present disclosure, a measurement value of the color difference is acquired for the display device to be evaluated, and the color-dependent visual sensitivity is considered using the color difference subjective evaluation result for the display device. The detection limit value of the color difference for the display device is obtained. Then, an evaluation parameter (number of evaluations) is obtained using the color difference measurement value and the color difference detection limit value, and the evaluation of the display characteristics of the display device is performed using the evaluation parameter. That is, display characteristics are evaluated based on an evaluation parameter obtained using a color difference detection limit value in consideration of color-dependent visibility. Thereby, objective display characteristic evaluation that matches human senses is realized as compared with the case where evaluation is performed without considering such color-dependent visual sensitivity. In addition, since the color reference image used when obtaining the measurement value of the color difference is set in advance using the visual evaluation result, the evaluation result with the display characteristic preferable for the user (viewer) as the target value Is obtained.

  According to the display device evaluation method of the present disclosure, a color difference measurement value for a display device to be evaluated is obtained, and a color difference in which a color-dependent visual sensitivity is considered using a subjective evaluation result of the color difference for the display device. The detection limit value is calculated, the evaluation parameter is obtained using the color difference measurement value and the color difference detection limit value, and the evaluation of the display characteristics of the display device is performed using this evaluation parameter. Matched objective display characteristic evaluation can be realized. In addition, since a color reference image used for obtaining a color difference measurement value is set in advance using a visual evaluation result, an evaluation result with a display characteristic preferable for the user as a target value is obtained. be able to. Therefore, it is possible to appropriately evaluate the display characteristics in the display device.

10 is a flowchart showing a display device evaluation method according to an embodiment of the present disclosure. It is a schematic diagram for demonstrating the measuring method of the color difference in a display apparatus. It is a figure showing an example of the measurement conditions in the case of the color difference measurement shown in FIG. It is a figure showing an example of the measurement result of a color difference. It is a schematic diagram for demonstrating the change of the target value by the difference in a measurement environment. It is a schematic diagram showing an example of the image used in the case of a subjective evaluation experiment. It is a characteristic view for demonstrating the relationship between a subjective evaluation experiment result and a detection limit color difference. It is a figure showing an example of the detection limit color difference obtained from the subjective evaluation experiment result. It is a figure showing an example of the color reproduction evaluation number obtained in the display apparatus. It is the figure which showed the color reproduction evaluation number shown in FIG. 9 according to the color. It is a block diagram showing the display apparatus concerning the example of application of this indication.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.

1. Embodiment (Method for evaluating color reproduction characteristics of display device using number of color reproduction evaluations)
2. Application example (display device using the number of color reproduction evaluations as an index)
3. Modified example

<Embodiment>
[Procedure for Display Device Evaluation Method]
FIG. 1 is a flowchart showing a main processing procedure in a display device evaluation method according to an embodiment of the present disclosure. The display device evaluation method of this embodiment evaluates display characteristics in a display device that displays a color image or the like, and here, color reproduction characteristics in the display device are evaluated.

(Acquisition of measured value of color difference: S11)
In this evaluation method, first, as shown in FIG. 2A, for example, using a spectral radiance meter 2, a measurement value (color difference ΔE ^* ) of the color difference in the display device 1 to be evaluated is acquired ( Step S11 in FIG. Specifically, for example, as shown in FIG. 2B, the display light Lout is transmitted from the display device 1 displaying a predetermined color reference image 31 described later on the display unit 10 to the spectral radiance meter 2. The color difference ΔE ^* , which is a measured value, is obtained by performing color measurement using

  At this time, as the size of the color reference image 31, for example, an aspect ratio (size in the vertical (V) direction / size in the horizontal (H) direction) = 1/5 can be used. As the background color, for example, a gray color (gray) of about 20% can be used. As will be described later, the color reference image 31 is an image set in accordance with the display condition so as to match the display condition of the display device 1.

  Here, as the display device 1 to be evaluated, for example, a display using various methods such as a CRT, an LCD, a PDP, and an organic EL display can be applied. Further, examples of such display applications include various types such as a monitor for TV (Television) and PC (Personal Computer).

The color difference ΔE ^* in the present embodiment corresponds to the color difference between the color reproduction (target value) preferable for the viewer (user) and the actual color reproduction (measured value) in the display device 1. . In other words, this corresponds to the color difference between the target value and the actual measurement value in the color reference image 31. Here, the color reference image 31 is an image set in advance using a result (visual evaluation result) of a visual evaluation (visual experiment) by a human (subject). As an environment (evaluation conditions) in such visual evaluation, for example, conditions as shown in FIG. Specifically, as an evaluation image for setting the color reference image 31 here, an image approximated to a Macbeth chart which is a standard color chart (here, “Face”: corresponding to skin color (# 2), “ “Green”: corresponding to the leaf color (# 4) of the tree, “Sky”: image corresponding to the sky blue (# 3), which uses three memory colors). In addition, 20 subjects with normal vision (10 men and 10 women) were used as subjects. Furthermore, color reproduction (brightness and chromaticity information) that is preferred by the user varies depending on display conditions (conditions such as brightness during viewing). Therefore, here, a general living environment (screen illuminance = 100 [lx], screen white luminance = approximately 160 [cd / m ² ]) and a general home theater environment (screen illuminance = 3 [lx], screen white) Measurement is performed with both luminance = about 50 [cd / m ² ]).

More specifically, as the color difference ΔE ^* in the present embodiment, for example, as shown by the following equations (1) to (4), the color difference by CIELAB assuming a uniform color space (in the CIELAB space described below) Color difference value) can be used. Specifically, first, on the basis of the (Xi, Yi, Zi) signal composed of the tristimulus values X, Y, Z obtained by the spectral radiance meter 2, the following ( (Luminance L ^* , saturation C ^* , hue H ^* ) are calculated using equations (2) to (4). These values are values in the CIE L ^* C ^* H ^* color space (CIELAB color space) defined by the CIE (International Commission on Illumination). This CIELAB color space is recommended as a uniform color space, and is a space that takes into account the uniformity of human perceptual color appearance.

Then, the image processing unit calculates the color difference ΔE ^* by using the values of (L ^* , C ^* , H ^* ) by the following equation (1). In the expressions (1) to (4), L ^* pref, C ^* pref, and hpref are target values (preferable color reproduction) of the luminance L ^* , saturation C ^* , and hue H ^{* in} the color reference image 31, respectively. Means. On the other hand, L ^* disp, C ^* disp, and hdisp mean measured values (actual color reproduction) of luminance L ^* , saturation C ^* , and hue H ^{* in} the color reference image 31, respectively.

Here, in the above formula (1) (calculation formula of the color difference ΔE ^* ), a predetermined weight may be set for each element of the luminance L ^* , the saturation C ^* , and the hue H ^* . That is, each term of (ΔL ^* ) ² , (ΔC ^* ) ² , (ΔH ^* ) ^{2 in} the equation (1) may be multiplied by an individual weighting coefficient. In such a configuration, the brightness at the time of the color difference Delta] E ^* calculation L ^*, chroma C ^*, since that would treat each element of the hue H ^* individually, capable of handling more precisely a color difference Delta] E ^* It becomes.

Note that the color difference ΔE ^* obtained in this way is influenced by the image quality characteristics of the display device 1, and therefore has a different value depending on the displayed reference color. Therefore, when the display device 1 is a TV device, it is preferable to use an image quality mode (for example, a custom mode or a cinema mode) in which an image is not created as much as possible as the image quality of the television at this time.

In this way, for example, a color difference ΔE ^* as shown in FIGS. 4A to 4D is obtained. Specifically, FIGS. 4A to 4C respectively show the approximate images (color reference image 31) of the three memory colors “Face”, “Green”, and “Sky” described above, and the color difference ΔE ^* . The relationship with each element (ΔL ^* , ΔC ^* , ΔH ^* ) of luminance L ^* , saturation C ^* , and hue H ^* is shown for each of the living environment and hall theater environment described above. In FIG. 4D, the results of FIGS. 4A to 4C are shown in a table. Note that the condition within the frame line indicated by the bold line in FIG. 4D means a condition that “color reproduction preferable for the user” is different between the living environment and the home theater environment.

Further, the color reference image 31 obtained in this way (target values of color differences ΔE ^* (ΔL ^* , ΔC ^* , ΔH ^* ) that define color reproduction preferable for the user) is, for example, FIGS. As shown in Fig. 4, it can be seen that it changes between the living environment and the hall theater environment described above.

(Detection limit color difference (color difference limit value) acquisition: S12)
Next, based on the result (subjective evaluation result) of a predetermined subjective evaluation experiment described below, the image processing unit obtains a detection limit color difference ΔEk, which is a color difference detection limit value for the display device 1 (step S12). . This detection limit color difference ΔEk corresponds to the minimum color difference value that can be perceived as having a difference, and as described later, is a color difference value that takes into consideration human visibility with color dependency. Yes.

  Here, the above subjective evaluation experiment is performed as follows, for example. Specifically, first, for example, as shown in FIG. 6, the above-described color reference image 32 and the color comparison image (color conversion image) 33 corresponding thereto are displayed in contrast on the display unit 10 of the display device 1. As the color comparison image 33, for example, using the eight reference colors in the Macbeth chart described above, the luminance (L axis), the saturation (C axis), and the hue (H axis) are respectively set to the color difference ΔE at predetermined intervals. It can be created by changing in the + (plus) direction and the-(minus) direction. Here, the eight reference colors in the Macbeth chart are the three primary colors R (red) (# 15), G (green) (# 14), and B (blue) (# 13), and the skin color ( This is a total of 8 colors: 3 memory colors of # 2), sky blue (# 3), leaf color (# 4), gray scale gradation 128 (# 22), gradation 64 (# 23) . Of these, for the gray color (# 22, H23), since the hue does not change, only the L axis and the C axis are changed.

  The experimenter can perceive the color difference ΔE between the color reference image 32 and the color comparison image 33 after sequentially displaying the plurality of color comparison images 33 thus obtained on the display unit 10. Judge at any time whether or not you can. Specifically, when it is determined that the color reference image 32 and the color comparison image 33 are the same color (the color difference ΔE cannot be perceived), the “Yes” button is pressed on the control switch at hand. Press it. On the other hand, when it is determined that the color reference image 32 and the color comparison image 33 are different colors (the color difference ΔE can be perceived), the “No” button is pressed on the control switch. The sequential display control of the plurality of color conversion images 33 and the totaling of the answer results by the experimenter are performed using, for example, a PC (not shown).

  As such a subjective evaluation experiment, for example, a limit method, a constant method, a double up / down method, or the like can be used. Among these, the double up-down method is used here in consideration of variation accuracy. This double up / down method is a method of displaying the color comparison image 33 by sequentially changing the color difference ΔE in the order of + → − from the larger direction. Since the reverse image on the axis with respect to the reference point is displayed, it is impossible to predict the order, and this is used as one of subjective evaluation experiments with high reliability of the obtained results.

  By the subjective evaluation experiment as described above, for example, a result (subjective evaluation result) as shown in FIG. 7 is obtained. In FIG. 7, the horizontal axis indicates the color difference ΔE (color differences along the L, C, and H axes) in the color comparison image 33. The vertical axis indicates the probability (probability that the color difference ΔE cannot be perceived) determined by the experimenter that the color reference image 32 and the color comparison image 33 are the same color (probability that the same color appears). The difference is 100% when the difference is completely unknown, and 0% when the difference is completely known. In this case, as shown in the figure, the value of the color difference ΔE when the probability of the same appearance is 50% is defined as the detection limit color difference ΔEk. Note that the dead zone ΔE0 shown in the drawing represents the range of the color difference ΔE when the probability of the same appearance is 100%.

  Here, FIG. 8 shows the detection along the L-axis, C-axis, and H-axis for each of the reference colors (eight colors # 2 to # 4, # 13 to # 15, # 22, and # 23). The limiting color differences ΔEk (L), ΔEk (C), ΔEk (H) and the average value of the detection limiting color differences for these eight colors are shown in a table. Here, there are various methods for obtaining the average value. For example, an arithmetic average, a geometric average, a harmonic average, or the like can be used. However, since a uniform color space is assumed as an example in this embodiment, the shape of the detection limit color difference is expected to be an ellipsoid, and the radius is considered to be the Euclidean distance. Therefore, here, as the average value of the detection limit color difference, as shown in the following equation (5), the square sum route of each detection limit color difference ΔEk (L), ΔEk (C), ΔEk (H) A value obtained by the average value (detection limit color difference ΔEk (√)) is used. It can be seen from FIG. 8 that the value of the detection limit color difference ΔEk is different for each color and each axis. In the following description, the detection limit color difference ΔEk (√) is used as the detection limit color difference ΔEk. However, the method for obtaining the average value is not limited to this depending on the color space used.

(Calculation of color reproduction evaluation number FR: S13)
Next, using the color difference ΔE ^* as the measurement value obtained in step S11 and the detection limit color difference ΔEk obtained in step S12, the image processing unit performs the evaluation number (evaluation parameter; preferred color) described below. The reproduction evaluation number FR) is obtained (step S13). If the color used in the evaluation does not completely match between the color difference ΔE ^* and the detection limit color difference ΔEk, if there is a color belonging to the same categorical color, it corresponds to that color. The detection limit color difference value ΔEk to be used may be used.

This color reproduction evaluation number FR is an evaluation number considering the sensitivity to human color change, and is defined as a measure of how many times the color difference ΔE ^* as the measured value corresponds to the detection limit color difference ΔEk. It is a thing. Specifically, the color reproduction evaluation number FR is defined by the following equation (6). That is, a color difference ratio ΔF which is a ratio (color difference ΔE ^* / detection limit color difference ΔEk) between the color difference ΔE ^* and the detection limit color difference ΔEk from the maximum value (100 points) defined in advance in the color reproduction evaluation number FR; The color reproduction evaluation number FR is obtained by subtracting the multiplication value from the color reproduction coefficient a which is a predetermined correction coefficient (adjustment coefficient). Here, the color reproduction coefficient a is a correction coefficient for adjusting the value of the color reproduction evaluation number FR, and is determined such that, for example, the average value (average point) of the color reproduction evaluation number FR is 80 points. . As described above, the color reproduction evaluation number FR obtained in this way is based on the increase in the value of the color difference ΔE ^{* on} the basis of the maximum value (full score) of 100 points (and the detection limit color difference ΔEk). As the value of becomes smaller, the value (score) decreases.

In the color difference ratio ΔF at this time, for example, as shown in the following equation (7), a predetermined weight is set for each element of luminance L ^* , saturation C ^* , and hue H ^* . That is, the individual weighting coefficients k1, k2, and (ΔL ^* / ΔEk (L)), (ΔC ^* / ΔEk (C)), and (ΔH ^* / ΔEk (H)) in the equation (7) k3 is multiplied. As a result, even if the weighting coefficient k1 = k2 = k3, each element of luminance L ^* , saturation C ^* , and hue H ^* is handled individually when calculating the color difference ratio ΔF. The color difference ratio ΔF can be handled more strictly.

  By such a method, for example, the color reproduction evaluation number FR as shown in FIGS. 9A and 9B and FIGS. 10A to 10D is obtained. Specifically, FIG. 9A illustrates reference colors (# 2 to # 4, # 13 to # 15, and # 22) in a plurality of types of display devices A to H as an example of the display device 1 (TV device). , # 23) and the average value FRav8 of the color reproduction evaluation number FR for these eight colors. FIG. 9B is a graph showing each color reproduction evaluation number FR shown in FIG. 9A. FIGS. 10A to 10D are shown in FIG. The graph is expressed in detail for each display device A to H and for each color. Here, the color reproduction evaluation number FR is obtained with the above-described color reproduction coefficient a = 10. 9 and 10, it can be seen that the value of the color reproduction evaluation number FR is different for each of the display devices A to H and for each color.

(Evaluation of display characteristics: S14)
Next, based on the color reproduction evaluation number FR thus obtained (utilized as an index value), for example, in the image processing unit, evaluation of display characteristics (here, color reproduction characteristics) in the display device 1 is performed. Is performed (step S14). Specifically, the color reproduction characteristics of the display device 1 are evaluated based on the color reproduction evaluation number FR. That is, it can be evaluated that the color reproduction characteristic in the display device 1 is better as the value of the color reproduction evaluation number FR is larger (as the score is closer to 100). On the other hand, the smaller the value of the color reproduction evaluation number FR (the closer the score is to 0), the worse the color reproduction characteristics of the display device 1 can be evaluated.

  For example, in the example of FIG. 9 and FIG. 10 described above, it can be seen that while there are display devices in which the average value HRav8 for eight colors shows a high value of nearly 80 points, there are also display devices that show a low value of about 50 points. . Further, for example, in the display device C, three basic colors (red (# 15), green (# 14), blue (# 13)), three memory colors (skin color (# 2), sky blue (# 3), and leaf color of the tree For each of (# 4)) and two gray colors (# 22, # 23), the average color reproduction evaluation FR shows a high value, and it can be said that the display device has particularly good color reproduction characteristics.

In this way, in the present embodiment, the color difference ΔE ^* as the measurement value is acquired for the display device 1 to be evaluated. In addition, the color difference detection limit value (detection limit color difference ΔEk) for the display device 1 in consideration of color-dependent visual sensitivity is obtained using the subjective evaluation result of the color difference for the display device 1. Then, an evaluation parameter (color reproduction evaluation number FR) is obtained using the color difference ΔE ^* and the detection limit color difference ΔEk, and the display characteristics (here, color reproduction characteristics) of the display device 1 are calculated using the color reproduction evaluation number FR. Is evaluated. That is, since the display characteristics are evaluated based on the color reproduction evaluation number FR obtained using the detection limit color difference ΔEk in consideration of the color-dependent visibility, such a color-dependent visibility is obtained. Compared to the case where evaluation is performed without consideration, objective display characteristic evaluation that matches human senses is realized. In addition, since the color reference image 31 used when acquiring the measurement value of the color difference ΔE ^* is set in advance using the visual evaluation result, a display characteristic preferable for the user (viewer) is set as the target value. Evaluation results are obtained.

As described above, in the present embodiment, the color difference ΔE ^* as the measurement value is acquired for the display device 1 to be evaluated, and the color-dependent visual sensitivity is obtained using the subjective evaluation result of the color difference for the display device 1. The detection limit color difference ΔEk in consideration of the color difference is obtained, the color reproduction evaluation number FR is obtained using the color difference ΔE ^* and the detection limit color difference ΔEk, and the display characteristics (color reproduction characteristics) of the display device 1 are calculated using the color reproduction evaluation number FR. ) Evaluation is performed, it is possible to realize objective display characteristic evaluation that matches human senses. In addition, since the color reference image 31 used for obtaining the measurement value of the color difference ΔE ^* is set in advance using the visual evaluation result, the display characteristic preferable for the user is evaluated as the target value. The result can be obtained. Here, the color reproduction required in a display device such as an actual TV device is a color reproduction that seems to be preferable to the viewer, and accurate color reproduction may not always be required. For these reasons, it is possible to appropriately evaluate the display characteristics in the display device by using the method of the present embodiment.

  In addition, by using the color reproduction evaluation number FR obtained in this way, it is possible to know at the design stage which color reproducibility should be improved by, for example, comparing accurate color reproduction characteristics for each TV apparatus. Can be fed back to the color design. On the other hand, there is an advantage that the user of the display device can know, for example, which color reproduction characteristic of the TV apparatus is superior by the magnitude of the color reproduction evaluation number FR. In other words, since the scale of display characteristics such as color reproduction characteristics can be shared, it is possible for designers and consumers to compare and examine the display characteristics of display devices using a common scale (index). Become.

  Furthermore, since objective display characteristic evaluation that matches the human sense is realized, it is possible to improve development and design efficiency by using it for quality evaluation at the development and design stages.

<Application example>
Next, an application example of the display device evaluation method according to the above embodiment will be described.

  FIG. 11 shows a block configuration of a display device (display device 4) using the display device evaluation method according to the above embodiment. The display device 4 uses the color reproduction evaluation number FR described in the above embodiment as an index when designing the video processing unit 43 described later. The display device 4 includes, for example, an MPEG (Moving Picture Expert Group) decoding unit 41, an illuminance sensor 42, a video processing unit 43, a display driving unit 44, and a display unit 45.

  The MPEG decoding unit 41 generates a decoded video signal D1 by performing an MPEG decoding process on the video signal Din consisting of an MPEG signal.

  The illuminance sensor 42 is a sensor that measures the illuminance of the external environment of the display device 4.

  The video processing unit 43 uses the video signal D1 and the illuminance detection value output from the illuminance sensor 42 to perform various video signal processings as shown in the figure, for example, so that the video after video signal processing is performed. The signal D2 is generated. As described above, the video processing unit 43 is obtained by using the color reproduction evaluation number FR as an index at the time of designing.

  The display driving unit 44 performs display driving for the display unit 45 based on the video signal D2. The display unit 45 performs video display based on the video signal Din in accordance with such display driving, and various types of displays such as a CRT, LCD, PDP, and organic EL display can be used. .

  In the display device 4, the color reproduction evaluation number FR is used as an index in designing, so that it is possible to obtain more preferable color reproduction characteristics for the user than in the past. In addition to the preferable color reproduction characteristics, the color reproduction characteristics include accurate (correct) color reproduction characteristics. The evaluation method of the present disclosure can also be applied to such color reproduction characteristics. It is.

<Modification>
The technology of the present disclosure has been described above with the embodiments and application examples, but the technology is not limited to these embodiments and the like, and various modifications are possible.

  For example, in the above-described embodiment, when the detection limit color difference ΔEk is obtained, the detection limit is the color difference ΔE when the probability that the color reference image 32 and the color comparison image 33 look the same (cumulative appearance number) is 50%. Although the color difference ΔEk is defined, it is not limited to this case. That is, the color difference ΔE when the probability of the same appearance is a value other than 50% may be defined as the value of the detection limit color difference ΔEk.

In the above-described embodiment and the like, the case where the color reproduction coefficient (correction coefficient) a is used as described in the above equation (6) when obtaining the color reproduction evaluation number FR has been described. The color reproduction coefficient a may not be used. That is, the color difference ratio ΔF itself, which is the ratio of the color difference ΔE ^* and the detection limit color difference ΔEk (color difference ΔE ^* / detection limit color difference ΔEk), is subtracted from the maximum value (100 points) in the color reproduction evaluation number FR. The reproduction evaluation number FR may be obtained.

  Furthermore, for example, the viewing angle characteristics (viewing angle characteristics) and the illumination environment characteristics of the display device may be evaluated using the color reproduction evaluation number FR described in the above embodiments and the like. That is, in the above embodiment, the color reproduction characteristic as an example of the display characteristic of the display device is evaluated. However, the present invention is not limited to this, and other display characteristics of the display device can be obtained using the color reproduction evaluation number FR. You may make it evaluate the viewing angle characteristic and illumination environment characteristic as an example. Specifically, for example, the viewing angle characteristics of the display device may be evaluated based on the amount of change in the color reproduction evaluation number FR corresponding to the change in angle during measurement (that is, viewing) of the display device. . Further, for example, the illumination environment characteristics may be evaluated by acquiring the color difference and the detection limit color difference while changing the illuminance of the external environment of the display device to be evaluated.

  In addition, the series of processes described in the above-described embodiments and the like may be performed by hardware (circuit) or software (program).

In addition, this technique can also take the following structures.
[1]
For the evaluation target display device displaying a predetermined color reference image set in advance using the visual evaluation result, obtain a measurement value of the color difference,
Using the subjective evaluation results of the color difference for the display device displaying the color reference image and the color comparison image in contrast, the color difference detection limit value for the display device in consideration of the color-dependent visual sensitivity Seeking
Obtain the evaluation parameter using the measured value of the color difference and the detection limit value of the color difference,
An evaluation method for a display device, wherein an evaluation relating to display characteristics of the display device is performed using the evaluation parameter.
[2]
The display device evaluation method according to [1], wherein the color reference image is an image set according to the display condition so as to match the display condition of the display device.
[3]
The display device evaluation method according to [1] or [2], wherein the color difference is a color difference between a target value and an actual measurement value in the color reference image.
[4]
A multiplication value of a color difference ratio, which is a ratio (measured value / detection limit value) between the measured value of the color difference and the detection limit value of the color difference, and a predetermined correction coefficient from a maximum value preliminarily defined in the evaluation parameter. The evaluation method for a display device according to any one of [1] to [3], wherein the evaluation parameter is obtained by subtraction.
[5]
By subtracting a color difference ratio, which is a ratio (measured value / detection limit value) between the measured value of the color difference and the detection limit value of the color difference, from the highest value prescribed in advance in the evaluation parameter, the evaluation parameter is The method for evaluating a display device according to any one of [1] to [3].
[6]
The method for evaluating a display device according to [4] or [5], wherein the color difference value in the CIELAB space is used.
[7]
In the color difference and the color difference ratio, predetermined weighting is set for each element of luminance, saturation, and hue. The method for evaluating a display device according to [6] above.
[8]
The display device evaluation method according to any one of [1] to [7], wherein the color reproduction characteristics of the display device are evaluated based on a size of the evaluation parameter.
[9]
The display device according to any one of [1] to [7], wherein a viewing angle characteristic of the display device is evaluated based on a change amount of the evaluation parameter according to a change in angle at the time of measurement with respect to the display device. Evaluation method.

DESCRIPTION OF SYMBOLS 1 ... Display apparatus (evaluation object) 10 ... Display part 2 ... Spectral radiance meter 31, 32 ... Color reference image, 33 ... Color comparison image (color conversion image), 4 ... Display apparatus, 41 ... MPEG decoding part , 42 ... Illuminance sensor, 43 ... Video processing unit, 44 ... Display drive unit, 45 ... Display unit, [Delta] E, [Delta] E ^* , [Delta] Ei ... Color difference, [Delta] Ek, [Delta] Ek (L), [Delta] Ek (C), [Delta] Ek (H), [Delta] Ek (√) ... detection limit color difference (color difference detection limit value), ΔE0 ... dead zone, a ... color reproduction coefficient (correction coefficient), FR, FRi ... color reproduction evaluation number, Lout ... display light, Din, D1, D2 ... video signal.

Claims (9)

For the evaluation target display device displaying a predetermined color reference image set in advance using the visual evaluation result, obtain a measurement value of the color difference,
Using the subjective evaluation results of the color difference for the display device displaying the color reference image and the color comparison image in contrast, the color difference detection limit value for the display device in consideration of the color-dependent visual sensitivity Seeking
Obtain the evaluation parameter using the measured value of the color difference and the detection limit value of the color difference,
An evaluation method for a display device, wherein an evaluation relating to display characteristics of the display device is performed using the evaluation parameter. The display device evaluation method according to claim 1, wherein the color reference image is an image set according to a display condition so as to match the display condition of the display device. The display device evaluation method according to claim 1, wherein the color difference is a color difference between a target value and an actual measurement value in the color reference image. A multiplication value of a color difference ratio, which is a ratio (measured value / detection limit value) between the measured value of the color difference and the detection limit value of the color difference, and a predetermined correction coefficient from a maximum value preliminarily defined in the evaluation parameter. The display device evaluation method according to claim 1, wherein the evaluation parameter is obtained by subtraction. By subtracting a color difference ratio, which is a ratio (measured value / detection limit value) between the measured value of the color difference and the detection limit value of the color difference, from the highest value prescribed in advance in the evaluation parameter, the evaluation parameter is The method for evaluating a display device according to claim 1. The evaluation method of the display device according to claim 4, wherein a color difference value in CIELAB space is used. The display device evaluation method according to claim 6, wherein a predetermined weight is set for each element of luminance, saturation, and hue in the color difference and the color difference ratio. The display device evaluation method according to claim 1, wherein the color reproduction characteristics of the display device are evaluated based on the size of the evaluation parameter. The display device evaluation method according to claim 1, wherein the viewing angle characteristic of the display device is evaluated based on a change amount of the evaluation parameter corresponding to a change in angle at the time of measurement of the display device.

Images