JP2006113151A - Image quality adjusting method of display device, image quality adjusting device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image quality adjusting method with which highly precise color reproduction is realized. <P>SOLUTION: The image quality adjusting method includes a color characteristic measuring step with which color characteristic data are measured for every R, G and B, a target data setting step with which color characteristic target data of an output image are set, a lookup table generating step with which a lookup table is generated and an image quality adjusting step with which the generated lookup table is assembled into a display device. The lookup table generating step is provided with a signal level setting step S31, a first color characteristic computing step S32 with which first color characteristic data are obtained for every R, G and B, a first luminance value computing step S33 with which first luminance values are computed, a second color characteristic computing step S34 with which second color characteristic data are obtained for every R, G and B, a second luminance value computing step S35 with which second luminance values are computed and a lookup table data computing step S36 which computes lookup table data. In the lookup table generating step, steps S32 to S36 are repeated to generate the lookup table while signal levels are varied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to image quality of various display devices such as a liquid crystal projector using a liquid crystal panel as a display body, a liquid crystal projection television, a direct-view type liquid crystal display, a plasma television using a PDP or an organic EL panel as a display body, and an organic EL display. The present invention relates to an adjustment method, an image quality adjustment device, and a display device.

  The transmission characteristics (transmittance characteristics with respect to drive voltage: VT characteristics) of a liquid crystal panel used in a three-plate liquid crystal projector or the like is a non-linear S-shaped curve. Since the characteristics vary among liquid crystal panels, color characteristic data for each of R (red), G (green), and B (blue) is measured in advance using a color luminance meter, and the measurement data is used as a basis. Variations for each liquid crystal panel are corrected by using the created lookup table (see, for example, Patent Document 1).

JP 2003-18415 A

By the way, it is known that the liquid crystal panel has a unique characteristic called an optical rotation dispersion characteristic, and the white balance in each gradation is lost. The optical rotatory dispersion characteristic is a phenomenon in which the light transmittance changes depending on the wavelength of light and the manner of change varies depending on the voltage. For this reason, when the voltage of the drive signal of each of the R, G, and B liquid crystal panels, that is, the gradation of the image displayed on the liquid crystal panel is changed, the color coordinates of the R, G, and B also change, and the white balance of each gradation The color reproducibility was deteriorated especially in the middle and low luminance regions.
Such a phenomenon that white balance or the like is lost and the color reproducibility is deteriorated when the gradation is changed by changing the drive signal level may occur not only in the liquid crystal panel but also in the PDP and the organic EL. is there.

  With regard to color reproducibility by these gradations, it has not been regarded as a problem so far, but in recent years, with the digitization of video signals and higher image quality, more accurate color reproducibility has been required, An image quality adjustment method, an image quality adjustment device, and a liquid crystal display device that can realize more accurate color reproducibility have been demanded.

  An object of the present invention is to provide an image quality adjustment method, an image quality adjustment device, and a display device that can realize highly accurate color reproducibility.

The image quality adjustment method of the display device of the present invention includes:
A color characteristic measurement step of measuring display body color characteristic data including luminance values and color coordinate values for each of R, G, and B with respect to a drive signal level of the display body capable of displaying three colors of R, G, and B;
A target data setting step of setting color characteristic target data of an output image when a predetermined level of drive signal is input to the display body;
A lookup table creating step for creating a lookup table that defines a relationship between an input signal input to the display device having the display body and a drive signal input to the display body according to the input signal;
An image quality adjustment step of incorporating the created lookup table into the display device,
The lookup table creation step includes:
A signal level setting step for setting the signal level;
A condition in which the normalized luminance value of each of the RGB display body color characteristic data is equal to the luminance value corresponding to the input signal of the level set in the signal level setting step in the normalized luminance value of the color characteristic target data A first color characteristic calculation step for obtaining first color characteristic data for each of RGB satisfying
A first luminance value calculation step of calculating a first luminance value for each RGB from the first color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
A second color characteristic calculation step for obtaining second color characteristic data for each RGB satisfying a condition in which the normalized luminance value of each of the RGB display body color characteristic data satisfies the same condition as the first luminance value;
A second luminance value calculating step of calculating a second luminance value for each RGB from the second color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
The normalized luminance values of the display body color characteristic data for each RGB obtain the respective RGB drive signal levels that satisfy the condition equal to the second luminance value, and the signal levels input to the display device and the RGB A lookup table data calculation step for calculating lookup table data indicating a relationship with the drive signal level,
While changing the signal level in the signal level setting step, the first color characteristic calculation step, the first luminance value calculation step, the second color characteristic calculation step, the second luminance value calculation step, lookup table data A lookup table is created by repeating the calculation process.

According to the present invention as described above, in the lookup table creation step, the luminance equal to the target luminance value of the color characteristic target data in the display body color characteristic data actually measured by the first color characteristic calculation step. First color characteristic data to be a value is calculated, and in the first luminance value calculation step, the first luminance value is calculated using the first color characteristic data. Furthermore, in the second color characteristic calculation step, second color characteristic data having a luminance value equal to the first luminance value in the actually measured display body color characteristic data is calculated to calculate the second luminance value. In the process, the second luminance value is calculated using the second color characteristic data. Then, based on the second luminance value, the drive signal level of each display body of RGB is obtained to create a lookup table.
That is, when calculating the drive signal level for each display element of each RGB that becomes the color characteristic target data, first, the provisional luminance is based on the first color characteristic data when it is equal to the luminance value of the target data. Since the value (first luminance value) is calculated, the second color characteristic data in the case of the temporary luminance value is obtained, and the luminance value (second luminance value) is calculated based on the color characteristic data. Even in a display body whose color coordinates change according to the gradation, that is, the drive signal, the luminance value is calculated based on the color coordinates of the actual gradation (luminance value). Thus, the luminance value can be calculated and a more accurate lookup table can be created. For this reason, the color reproducibility in each of the low, medium and high luminance regions can be improved.

In the present invention, the target data setting step includes an ideal gray curve creating step for creating an ideal gray curve indicating a change in chromaticity coordinates of an achromatic color with respect to an input signal in the display device; gamma correction data in the display device; It is preferable to include an ideal curve color coordinate data creating step of creating ideal curve color coordinate data that is color characteristic target data from the ideal gray curve.
Here, the ideal gray curve may be set for each mode, for example, when there are a display mode that prioritizes brightness and a display mode that prioritizes color reproduction.

If an ideal gray curve creation step and an ideal curve color coordinate data creation step are provided, it is possible to easily create color characteristic target data for each display mode by setting an ideal gray curve for each display mode. Further, it is possible to easily create color characteristic target data corresponding to various input signals having different gamma characteristics using gamma correction data corresponding to various gamma characteristics.
Accordingly, a lookup table corresponding to various modes can be easily created.

In the present invention,
In the first color characteristic calculation step, the normalized luminance value of each of the RGB display body color characteristic data has a level set in the signal level setting step in the normalized luminance value of the color characteristic target data. First R color tristimulus values (Xrt, Yrt, Zrt), G first tristimulus values (Xgt, Ygt, Zgt) and B color first conditions satisfying the same condition as the luminance value corresponding to the input signal Find the tristimulus value of 1 (Xbt, Ybt, Zbt)
In the first luminance value calculation step, the first color characteristic data for each RGB is obtained from the RGB color characteristic data calculated in the first color characteristic calculation step and the color characteristic target data corresponding to the set input signal level. Calculate luminance values (Yr, Yg, Yb)
In the second color characteristic calculation step, the second color of R color satisfying the condition that the normalized luminance value of each of the RGB display body color characteristic data is equal to the first luminance value (Yr, Yg, Yb). Tristimulus values (Xrt ', Yrt', Zrt '), G color second tristimulus values (Xgt', Ygt ', Zgt'), B color second tristimulus values (Xbt ', Ybt') , Zbt ')
In the second luminance value calculation step, a second color value for each RGB is calculated from each color characteristic data of RGB calculated in the second color characteristic calculation step and color characteristic target data corresponding to the set input signal level. It is preferable to calculate the luminance values (Yr ′, Yg ′, Yb ′).

At this time, the tristimulus value of the color characteristic target data corresponding to the input signal at the level set in the signal level setting step in the color characteristic target data is set to (X, Y, Z), and black is displayed on the display device. When the tristimulus values are (Xbk, YbK, Zbk)
In the first luminance value calculating step, a first luminance value (Yr, Yg, Yb) is obtained by the following equation (1), and in the second luminance value calculating step, a second luminance value (Yr ′ , Yg ′, Yb ′) is preferably obtained by the following equation (2).

According to the present invention, in the first and second color characteristic calculation steps, the normalized luminance value of the display body color characteristic data is set to be equal to the color characteristic target data and the first luminance value. Since the first and second tristimulus values are calculated and the calculation process is almost the same, the processing program can be shared and easily processed.
In addition, since the first and second luminance value calculation steps are almost the same as shown in the equations (1) and (2), the processing program can be made common in this respect and can be easily processed. .

Here, the display device is preferably a three-plate liquid crystal projector having three liquid crystal panels for RGB as a display body.
Various display devices such as a liquid crystal display, a plasma television, and an organic EL display can be used as the display device. However, even in a three-plate liquid crystal projector having three liquid crystal panels for RGB, the display body color characteristics of each panel. If the data is measured, a lookup table can be created by data processing using the measurement data and the color characteristic target data, etc., so that the image quality can be adjusted efficiently.

The image quality adjusting device of the display device of the present invention is
Color characteristic measuring means for measuring display body color characteristic data including luminance values and color coordinate values for each of R, G, and B with respect to a drive signal level of a display body capable of displaying three colors of R, G, and B;
Target data setting means for setting color characteristic target data of an output image when a predetermined level of drive signal is input to the display body;
Lookup table creating means for creating a lookup table that defines a relationship between an input signal input to the display device having the display body and a drive signal input to the display body according to the input signal;
Image quality adjustment means for incorporating the created lookup table into the display device,
The lookup table creation means includes:
Signal level setting means for setting the signal level;
A condition in which the normalized luminance value of each of the RGB display body color characteristic data is equal to the luminance value corresponding to the input signal of the level set by the signal level setting means in the normalized luminance value of the color characteristic target data First color characteristic calculation means for obtaining first color characteristic data for each of RGB satisfying
First luminance value calculating means for calculating a first luminance value for each RGB from the first color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
Second color characteristic calculation means for obtaining second color characteristic data for each RGB satisfying a condition in which normalized luminance values of the respective RGB display body color characteristic data are equal to the first luminance value;
Second luminance value calculation means for calculating a second luminance value for each RGB from the second color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
The normalized luminance value of the display body color characteristic data for each RGB obtains each RGB drive signal level satisfying the condition equal to the second luminance value, and the signal level input to the display device and each RGB Lookup table data calculating means for calculating lookup table data indicating the relationship with the drive signal level;
While changing the signal level by the signal level setting means, the first color characteristic calculating means, the first luminance value calculating means, the second color characteristic calculating means, the second luminance value calculating means, look-up table data A lookup table is created using a calculation means.
Also in the present invention, the same effects as the image quality adjustment method of the display device can be obtained.

The display device of the present invention includes a display body that can display three colors of R, G, and B, and a drive control circuit unit that drives the display body. The drive control circuit unit adjusts the image quality of the display device. The driving of the display body is controlled using a look-up table created by the method.
In the display device of the present invention, since the lookup table created by the image quality adjustment method is incorporated, color reproducibility can be improved. Accordingly, video data of a high-definition television can be reproduced and displayed with high accuracy.

  Here, a three-plate type liquid crystal projector having three liquid crystal panels for RGB as the display body is preferable. If the display body color characteristic data of each panel is measured, then a lookup table can be created by data processing using measurement data and color characteristic target data, etc., so that image quality adjustment can be performed efficiently.

Hereinafter, an image quality adjustment apparatus according to an embodiment of the present invention will be described.
As shown in FIG. 1, the image quality adjustment device 3 of the present embodiment controls driving of a liquid crystal projector 1 that is a display device to be measured, and measures the chromaticity and luminance of an image displayed on the liquid crystal projector 1. The data measured by the color luminance meter 2 is processed.

In the present embodiment, the three-plate liquid crystal projector 1 is exemplified as the display device, but various display devices such as a liquid crystal display, a plasma television, and an organic EL display may be measured.
The liquid crystal projector 1 includes a liquid crystal panel 11 that is a display body that displays an image, and a drive control unit 12 that controls driving of the liquid crystal panel 11. In the three-plate liquid crystal projector 1, three liquid crystal panels 11 are provided, and each displays R (red), G (green), and B (blue) colors.
A display body in a liquid crystal projector or a liquid crystal display is composed of a liquid crystal panel 11, but is composed of a plasma display panel (PDP) in a plasma television and an EL panel in an organic EL display.

The drive control unit 12 is configured by a drive IC or the like, applies a drive signal to each liquid crystal panel (display body) 11 and controls the signal level (drive voltage value or drive current value) of the drive signal, The brightness value of the output image of the liquid crystal panel 11 is adjusted.
In the present embodiment, the drive control unit 12 is set to drive the liquid crystal panel 11 using an 8-bit or 10-bit control signal. For example, if a 10-bit control signal is used, the drive voltage of the liquid crystal panel 11 can be controlled by switching to 1024 gradations.
Since the PDP and the organic EL panel are self-luminous flat panels, the luminance value of the image is directly controlled by the signal level, but the liquid crystal panel 11 functions as a light valve that adjusts the light amount of the backlight. The luminance value of the image is adjusted by controlling the light transmittance at the signal level.
The color luminance meter 2 can measure chromaticity and luminance and output the data, and since it is a general one used conventionally, description thereof is omitted.

The image quality adjustment device 3 is configured by a computer device, and is connected to the liquid crystal projector 1 via an interface such as RS-232C.
The image quality adjustment device 3 includes a measurement control unit 31, an image quality adjustment unit 32, and a storage unit 33.

The measurement control unit 31 includes a color characteristic measurement unit 311 and a color characteristic data processing storage unit 312.
The color characteristic measuring unit 311 controls the drive control unit 12 to set the liquid crystal projector 1 to the adjustment mode, sequentially switches the drive signal level of the liquid crystal panel 11, and changes the chromaticity and luminance of the image displayed at that time. The color luminance meter 2 is used for measurement. For example, the color characteristic measuring unit 311 uses an 8-bit drive signal that can switch the drive signal level of the liquid crystal panel 11 from 0 to 255, and sequentially inputs 33 signal levels to display an image. Is measured using a color luminance meter 2.
In addition, when the liquid crystal projector 1 is set to the adjustment mode by the color characteristic measuring unit 311, all the correction processes related to the output process for the input signal are set to off. Therefore, the color characteristic measuring unit 311 measures the prime color characteristic data of each liquid crystal panel 11.

The color characteristic data processing storage unit 312 stores the RGB color characteristic data in the storage unit 33 based on the data measured by the color characteristic measurement unit 311.
In the present embodiment, the storage unit 33 stores the drive signal level and the color coordinates at the signal level as tristimulus values (X, Y, Z) for each RGB. For this reason, when the tristimulus values (X, Y, Z) for each RGB are directly measured by the color characteristic measuring unit 311, the color characteristic data processing storage unit 312 stores the measurement data as it is in the storage unit 33.
On the other hand, when the color characteristic measurement unit 311 measures the chromaticity coordinates and luminance values of red, green, and blue, the color characteristic data processing storage unit 312 converts the measurement data into tristimulus values and stores them. 33.

The image quality adjustment unit 32 includes target data setting means 35, lookup table creation means 36, and image quality adjustment means 37.
As shown in FIG. 2, the target data setting unit 35 includes an ideal gray curve creation unit 351 and an ideal curve color coordinate data creation unit 352.

  The ideal gray curve creating means 351 creates an ideal gray curve corresponding to each display mode in order to create a look-up table corresponding to each display mode of the liquid crystal projector 1. In the present embodiment, the gray curve indicates a change in chromaticity coordinates (x, y) of an achromatic color (black to gray to white) with respect to each signal level of an input signal (driving signal).

  The ideal curve color coordinate data creating means 352 creates ideal curve color coordinate data serving as color characteristic target data from the ideal gray curve data and the gamma correction data in the liquid crystal projector 1.

  The look-up table creation unit 36 includes a signal level setting unit 361, a first color characteristic calculation unit 362, a first luminance value calculation unit 363, a second color characteristic calculation unit 364, and a second luminance value. Calculation means 365 and lookup table data calculation means 366 are provided.

  The signal level setting unit 361 sets a signal level for data processing. For example, when creating a look-up table that represents the relationship between the input signal to the liquid crystal projector 1 and the drive signal to the liquid crystal panel 11, when the input signal is set to 10 bits, the signal level setting means 361 At the time of data processing in the lookup table creation means 36, the signal level is switched to 1024 steps from 0 to 1023.

The first color characteristic calculation means 362 performs RGB when assuming that the luminance value of each liquid crystal panel 11 is equal to the luminance value of the target data (ideal curve color coordinate data) in the RGB color characteristic data of each liquid crystal panel 11. The first color characteristic data for each is obtained.
The first luminance value calculation unit 363 calculates the first luminance value of each liquid crystal panel 11 using the first color characteristic data obtained by the first color characteristic calculation unit 362.

The second color characteristic calculation unit 364 assumes that the luminance value of each liquid crystal panel 11 is equal to each luminance value calculated by the first luminance value calculation unit 363 in the RGB color characteristic data of each liquid crystal panel 11. In this case, the second color characteristic data for each RGB is obtained.
The second luminance value calculating unit 365 calculates the second luminance value of each liquid crystal panel 11 using the second color characteristic data obtained by the second color characteristic calculating unit 364.

  The look-up table data calculation means 366 calculates look-up table data indicating the relationship between the input signal to the three-panel liquid crystal projector 1 and the drive signal to the liquid crystal panel 11 when the second luminance value is obtained, and stores it. This is stored in the unit 33.

  The image quality adjustment unit 37 registers the created lookup table in the memory of the liquid crystal projector 1.

The storage unit 33 includes a memory, and stores gamma correction data 331, color characteristic data 332, and LUT data 333, as shown in FIG.
The gamma correction data 331 stores an input signal input to the liquid crystal projector 1 and a value obtained by raising the signal value to an exponent γ (gamma value). In the present embodiment, the gamma value γ is 2.2 in order to have the same characteristics as the CRT.
The color characteristic data 332 stores the prime color characteristic data of each liquid crystal panel 11 measured by the measurement control unit 31.
The LUT data 333 stores the lookup table data created by the lookup table creation means 36.

Hereinafter, an image quality adjustment processing procedure in the image quality adjustment apparatus 3 will be described.
When the image quality adjustment process is instructed, the image quality adjustment apparatus 3 initializes the liquid crystal projector 1 (step 1, hereinafter “step” is abbreviated as “S”) and the ideal color coordinates of the liquid crystal projector 1 as shown in FIG. The setting process S2, the lookup table creation process S3, the image quality adjustment process S4, and the adjustment mode end process S5 are sequentially executed.

[1. Initialization process]
When the image quality adjustment processing is instructed by an inspector's instruction or the like, the image quality adjusting device 3 sets the liquid crystal projector 1 to the adjustment mode, cancels the correction mode set in the liquid crystal projector 1 and initializes it (S1). ). Thereby, the elementary color characteristic data of the liquid crystal panel 11 can be measured.

[2. Ideal color coordinate setting process]
When the initialization process S1 ends, the image quality adjustment device 3 executes an ideal color coordinate setting process S2. Here, as shown in FIG. 4, the ideal color coordinate setting process S2 includes a color characteristic measurement process of the liquid crystal panel 11 and a target data setting process.
[2.1 Color characteristic measurement process of LCD panel]
The color characteristic measurement step includes a color coordinate measurement step S21 and a color characteristic data processing storage step S22.
[2.1.1 Color coordinate measurement process]
First, the image quality adjusting device 3 operates the color characteristic measuring unit 311 of the measurement control unit 31 to measure the prime color coordinates (color characteristic data) of the R, G, B liquid crystal panels 11 of the liquid crystal projector 1 (S21). ). At this time, the color characteristic measuring means 311 individually changes the R, G, B liquid crystal panels 11 to 0 to 100% and measures the color characteristic data at that time using the color luminance meter 2. For example, when the liquid crystal panel 11 is driven by inputting an 8-bit drive signal, that is, when it can be changed to 256 gradations from 0 to 255, 33 points of the signals are input, and the color characteristic data at that time (For example, tristimulus values X, Y, Z) are measured by the color luminance meter 2.

[2.1.2 Color characteristic data processing storage process]
Next, the color characteristic data processing storage unit 312 of the measurement control unit 31 appropriately processes the color coordinate data measured by the color characteristic measurement unit 311 and stores it in the color characteristic data 332 of the storage unit 33 (S22).
That is, in the present embodiment, since the color characteristic data 332 is set to store tristimulus values (XYZ values), the color characteristic measurement unit 311 uses the tristimulus values (XX) as the color coordinates of each liquid crystal panel 11. , Y, Z), the color characteristic data processing storage unit 312 directly stores the measurement data in the color characteristic data 332. On the other hand, when the chromaticity coordinates (x, y) and the luminance value Y are measured by the color characteristic measurement unit 311, the color characteristic data processing storage unit 312 processes these measurement data to obtain tristimulus values (X , Y, Z), and stores the calculated XYZ values in the color characteristic data 332.
When the tristimulus values (color coordinates) of these RGB liquid crystal panels 11 are plotted on a graph, they are as shown in FIG.

[2.2 Target data setting process]
Next, the image quality adjusting device 3 operates the target data setting means 35 of the image quality adjusting unit 32 to execute the target data setting process. As shown in FIG. 4, the target data setting step includes an ideal gray curve creation step (S23) and an ideal curve color coordinate creation step (S24).

[2.2.1 Ideal gray curve creation process]
The ideal gray curve creating means 351 of the target data setting means 35 creates an ideal gray curve that is the target of the display characteristics of the liquid crystal projector 1 (S23).
As the target data, for example, the target color coordinates may be set so as to match a color standard such as sRGB. For example, in the definition of sRGB, white chromaticity coordinates (xwt = 0.3127, ywt = 0.3290), red chromaticity coordinates (xrt = 0.6400, yrt = 0.3300), green chromaticity coordinates (xgt = 0.3000, ygt = 0.6000). ), Blue chromaticity coordinates (xbt = 0.1500, ybt = 0.0600).

  As shown in FIG. 7, the ideal gray curve creating means 351 generates an ideal gray curve (xy coordinate data when displaying achromatic colors from black to gray to white) in the liquid crystal projector 1 with the chromaticity coordinates as a reference. create. Since this Gray curve is an achromatic color, even if the input value (drive signal level) changes as shown by the chromaticity coordinates (xy coordinates) as shown by the target lines L1 and L2 shown by the dotted lines in FIG. Ideally, the chromaticity coordinates are constant, that is, the x and y values are constant, and only the brightness changes. Therefore, in the case of the display mode in which color reproducibility is prioritized in the liquid crystal projector 1, an ideal substantially along the target lines L1 and L2 where the chromaticity coordinates (x, y) are constant regardless of changes in input values. A gray curve may be used. For example, the chromaticity coordinates (xkt, ykt) when the drive signal levels of the liquid crystal panels 11 are all “0” are measured values when the display is actually all black, that is, the minimum luminance that can be displayed on the liquid crystal projector 1. It is only necessary to create ideal gray curves along the target lines L1 and L2 from gray to all white display.

On the other hand, the liquid crystal projector 1 has a mode in which priority is given to brightness in addition to a mode in which priority is given to color.
In this brightness priority mode, the chromaticity coordinates (xwt, ywt) when the drive signal levels of each liquid crystal panel 11 are all set to “255” and all white display is performed are measured values when the all white display is actually performed, That is, the maximum luminance value that can be displayed on the liquid crystal projector 1 may be used.
Similarly, the chromaticity coordinates (xkt, ykt) when the drive signal levels of each liquid crystal panel 11 are all “0” are measured values when actually displaying all black, that is, the minimum value that can be displayed on the liquid crystal projector 1. A luminance value may be used.

  Therefore, the ideal Gray curve in the liquid crystal projector 1 in the brightness priority mode is all when the input is “0” as shown by a solid line (x coordinate) and a two-dot chain line (y coordinate) in FIG. When the measured chromaticity mark (xkt, ykt) is black and the input is the maximum value (for example, 1023 for a 10-bit signal), the measured chromaticity coordinates (xwt, ywt) are all white, and the input value is predetermined. If it is in the range of, the xy coordinate value may be set to be constant, that is, to be on the target line. Note that the curve portion from each measurement coordinate (xkt, ykt), (xwt, ywt) to the chromaticity coordinate becoming a constant value may be set depending on the characteristics of the liquid crystal projector 1. In particular, it may be set depending on to what input value the influence of plain white is affected.

[2.2.2 Process of creating ideal curve color coordinates (X, Y, Z)]
Next, the ideal curve color coordinate data creating means 352 creates XYZ values that are the color coordinates of the ideal curve from the gray curve and the gamma characteristic data (S24). That is, an XYZ value of an ideal curve as shown in FIG. 8 is obtained from each chromaticity coordinate data of the Gray curve and the gamma characteristic (luminance characteristic) in the liquid crystal projector 1. This ideal curve is a tristimulus value XYZ value that is a target of a gray image projected from the liquid crystal projector 1. The gamma characteristic is set to a gamma characteristic with a γ value = 2.2, that is, a power of 2.2 in accordance with the characteristics of the CRT.
Note that the ideal curve is normalized so that the Y value changes from 0 to 1.0 with respect to the input signals 0 to 1023. Therefore, the normalized luminance value (Y value) matches the transmittance of the liquid crystal panel 11.

[3. Lookup table (LUT) creation process]
Next, the image quality adjustment device 3 operates the lookup table creation means 36 of the image quality adjustment unit 32 to create a lookup table (LUT).
[3.1 Signal level setting process]
As shown in FIG. 5, the lookup table creation means 36 first sets the signal level by the signal level setting means 361 (S31). The signal level is input condition data at the time of LUT creation processing, and corresponds to the input signal level in the LUT indicating the relationship between the input signal of the liquid crystal projector 1 and the drive signal of the liquid crystal panel 11.
In this embodiment, while changing the input signal Sn from 0 to 1023 in 1024 steps, the processing of S32 to S36 described below is repeated to create an LUT. In the following description, the case where the input signal Sn = 550 is illustrated and described.

[3.2 First color characteristic calculation process]
Next, the look-up table creation unit 36 operates the first color characteristic calculation unit 362 to calculate the first color characteristic by obtaining XYZ for each RGB corresponding to the Y value of the color coordinate of the ideal curve. (S32).
The ideal curve obtained in the ideal color coordinate setting process S2 is an XYZ value of the output image of the liquid crystal projector 1. The XYZ values of the output image are the values of the R display liquid crystal panel (R panel) 11, the G display liquid crystal panel (G panel) 11, and the B display liquid crystal panel (B panel) 11 based on the principle of additive color mixing. Each tristimulus value XYZ value is added.
Therefore, the first color characteristic calculating unit 362 first obtains a luminance value (transmittance) from the Y value of the ideal curve for the input signal Sn (= 550), and the same luminance value is obtained in the color coordinate data of each panel 11. The XYZ value is obtained when That is, assuming that the luminance value (transmittance) of the ideal curve for the predetermined input signal Sn is the same as the luminance value (transmittance) of each panel 11 when the XYZ values of the RGB panels 11 are added, It becomes the same as the brightness value of each panel.

For this reason, as shown in FIGS. 9 to 11, the first color characteristic calculation means 362 changes each Y value from 0 to 1023 for each Y value in the color coordinate data of each panel 11 of RGB measured in S2. Yr, Yg, and Yb normalized so as to be 0 to 1.0 with respect to the case of being made are plotted on the graph.
Then, as shown in FIGS. 9 to 11, an ideal curve Y value (luminance value) with respect to a predetermined input signal Sn (= 550) is obtained, and in each normalized Yr, Yg, Yb graph, the Y value An input value (horizontal axis value) is obtained, and tristimulus values XYZ of the RGB panels 11 corresponding to the input value are obtained. That is, the tristimulus values (Xrt, Yrt, Zrt) in the R panel, the tristimulus values (Xgt, Ygt, Zgt) in the G panel, and the tristimulus values (Xbt, Ybt, Zbt) in the B panel are obtained. These tristimulus value data become the first color characteristic data.

[3.3 First luminance value calculation step]
Next, the look-up table creation means 36 operates the first luminance value calculation means 363, and determines the luminance (Yr, Yr, Y) of each panel from the XYZ values of the RGB panels 11 obtained in the first color characteristic calculation step S32. By calculating Yg, Yb), the first luminance value is calculated (S33).
That is, in the first color characteristic calculation step S32, it is assumed that the brightness of each panel 11 is equal to each other, but actually, there is a high possibility that the brightness is different for each panel 11. Therefore, in the first luminance value calculation step S33, an approximate value (first luminance value) of the actual luminance value of each panel 11 is obtained based on the color characteristic data calculated in the first color characteristic calculation step S32. ing.

Here, the XYZ value of the ideal curve and the XYZ value of each panel 11 are in the relationship of the following formula (3).

Here, X, Y, and Z are tristimulus values for the predetermined input signal Sn of the ideal curve, and Xbk, Ybk, and Zbk are tristimulus values when the liquid crystal projector 1 displays black. Xbk, Ybk, and Zbk are added because the liquid crystal projector 1 controls the brightness of the backlight (light source) by adjusting the transmittance of each liquid crystal panel 11, and the transmission of the liquid crystal panel 11. This is because even when black display is performed with the rate set to 0, there is leakage of the backlight or the like, and it is necessary to add the offset.
If this relationship is expressed by a determinant, the following equation (4) is obtained.

  If the luminance (Yr, Yg, Yb) of each of the RGB panels 11 is obtained by modifying this equation (4), equation (5) is obtained.

  Therefore, the first luminance value (Yr, Yg, Yb) can be calculated by substituting the first color characteristic data or the like into the equation (5).

[3.4 Second color characteristic calculation process]
Next, the look-up table creation unit 36 operates the second color characteristic calculation unit 364 to again calculate the XYZ values for each of the RGB panels 11 from the first luminance value calculated in the first luminance value calculation step S33. By calculating the second color characteristic, the second color characteristic is calculated (S34).

The tristimulus values (first color characteristic data) of each panel 11 in equation (5) are for the case where the luminance value is equal to the Y value of the ideal curve, and the luminance of each panel 11 obtained by equation (5). It is not the value in the case of (Yr, Yg, Yb).
For this reason, the second color characteristic calculation unit 364 calculates again the tristimulus values of each panel 11 corresponding to the luminance (Yr, Yg, Yb) calculated by the equation (5). Specifically, as shown in FIGS. 12 to 14, since the first luminance value for the input signal Sn is obtained by the equation (5), each of the RGB panels 11 measured in the color coordinate measurement step S21 is obtained. In the measurement data (the graphs on the left side of FIGS. 12 to 14), the input value (horizontal axis value) at the point where the normalized Yr, Yg, Yb values become the luminance values (Yr, Yg, Yb) is obtained. . Then, the tristimulus values XYZ of the RGB panels 11 corresponding to the input values are obtained. That is, tristimulus values in the R panel (Xrt ′, Yrt ′, Zrt ′), tristimulus values in the G panel (Xgt ′, Ygt ′, Zgt ′), tristimulus values in the B panel (Xbt ′, Ybt ′, Zbt) ') Ask. These tristimulus value data become the second color characteristic data.

[3.5 Second luminance value calculation step]
Next, the look-up table creation unit 36 operates the second luminance value calculation unit 365 to calculate each panel 11 from the second color characteristic data of each RGB panel 11 obtained in the second color characteristic calculation step S34. The second luminance value (Yr ′, Yg ′, Yb ′) is calculated by obtaining the luminance (S35).
That is, the second luminance value calculating means 365 calculates the actual luminance value of each panel 11 based on the XYZ value for each panel 11 obtained in the second color characteristic calculating step S34 by the following equation (6). Use to calculate. Expression (6) is obtained by replacing each tristimulus value of the conversion matrix in Expression (5) with the tristimulus value obtained in the second color characteristic calculation step S34.

  Therefore, the second luminance value (Yr ′, Yg ′, Yb ′) can be calculated by substituting the second color characteristic data or the like into Expression (6).

[3.6 LUT data calculation process]
Next, the lookup table creation unit 36 operates the lookup table data calculation unit 366. As shown in FIGS. 15 to 17, the look-up table data calculation unit 366 uses the brightness values (each panel 11 calculated in the second brightness value calculation step S <b> 35 in each normalized graph of Yr, Yg, Yb). Yr ′, Yg ′, Yb ′) are obtained as input values (horizontal axis values).
For example, when the input signal Sn = 550, a drive signal Sr = 680 to be input to the R panel, a drive signal Sg = 655 to be input to the G panel, and a drive signal Sb = 640 to be input to the B panel are obtained. .
The lookup table data calculation unit 366 stores each calculated drive signal in the LUT data 333 in association with the input signal Sn.

[3.7 Measurement count confirmation process]
Next, the look-up table creation means 36 checks whether or not data calculation has been performed for a preset number (S37). For example, in the signal level setting step S31, when n is changed from 0 to 1023 as the level of the input signal Sn in 1024 steps (gradation), that is, when n is set so as to indicate the number of calculations, measurement is performed. In the number confirmation step S37, it is determined that the data has been calculated for the set number when n becomes 1023, and the lookup table creation process S3 is terminated.
On the other hand, when the set number of data is not calculated in the measurement number confirmation step S37, the process returns to the signal level setting step S31, the signal level is changed by one step, and the steps S32 to S36 are repeated. That is, S32 to S36 are repeated while changing the input signal Sn from 0 to 1023. As a result, a drive signal to be input to each of the RGB panels 11 is obtained for each input signal Sn, so that an LUT having a VT characteristic can be created.
As shown in FIG. 18, the LUT is represented by a graph in which the input signal Sn is on the horizontal axis and the drive signals to the RGB panels are on the vertical axis.

[4 Image quality adjustment processing]
When the look-up table creation process S3 is completed, the image quality adjustment unit 37 of the image quality adjustment unit 32 registers the created look-up table (LUT) data 333 in the memory in the liquid crystal projector 1 (S4). As a result, the image / video signal input to the liquid crystal projector 1 is subjected to correction processing using the LUT data 333 in the drive control unit 12 and input to the liquid crystal panel 11. For this reason, the liquid crystal projector 1 performs image quality adjustment suitable for displaying a general video signal (a signal of γ = 1 / 2.2 matched to the characteristics of the CRT).

[5 Adjustment mode end processing]
When the image quality adjustment process S4 ends, the image quality adjustment device 3 ends the adjustment mode (S5). Thereby, the adjustment mode of the liquid crystal projector 1 is also canceled.

According to the first embodiment described above, there are the following effects.
(1) When creating an LUT so that the XYZ value of the output image corresponding to the input signal Sn to the liquid crystal projector 1 becomes the XYZ value of the ideal curve, first, the luminance value (transmittance) of each panel 11 is the ideal curve. An XYZ value of each panel 11 is obtained by setting it equal to the Y value (luminance value), an approximate value of the actual luminance value of each panel 11 is obtained, and each panel 11 for this approximate luminance value (Yr, Yg, Yb) is obtained. The XYZ values are calculated again, and the luminance values (Yr ′, Yg ′, Yb ′) of each panel 11 are calculated using the XYZ values. Accordingly, the correct luminance value can be obtained using the measured values of the tristimulus values of each panel 11 in a state approximate to the actual luminance values (Yr ′, Yg ′, Yb ′) of each panel 11, so that the optical rotation dispersion Even when the color coordinate changes according to the change of the gradation (input value) like the liquid crystal panel 11 having characteristics, the correct luminance value is calculated by using the measurement data of the tristimulus value approximated to the actual luminance value. As a result, a more accurate LUT can be created.
For this reason, more accurate color reproducibility can be realized even in the middle / low luminance region than in the conventional case where the white balance is lost in the middle / low luminance region and the color reproducibility is lowered due to the optical rotation dispersion characteristic. Therefore, in the liquid crystal projector 1, color reproducibility can be improved over the entire low, medium and high luminance regions.

(2) Since the target data setting means 35 includes the ideal gray curve creation means 351 and the ideal curve color coordinate data creation means 352, an ideal gray curve can be easily set for each display mode. Color characteristic target data for each display mode can be easily created.
Further, it is possible to easily create color characteristic target data corresponding to various input signals having different gamma characteristics using gamma correction data corresponding to various gamma characteristics. Accordingly, a lookup table corresponding to various modes can be easily created.
In addition, since the ideal curve is data that takes into account the gamma characteristic of the power of 2.2, the LUT data 333 can be adapted to the display characteristics of the CRT. For this reason, the liquid crystal projector 1 can be a display device suitable for displaying general video / image data based on the output from the CRT.

(3) Since the processing for calculating the first and second color characteristics by applying predetermined luminance values to the normalized Yr, Yg, Yb in S32 and S34 is basically the same processing, the processing program is also the same. Routines can be used and processed efficiently.
Similarly, since the equations (5) and (6) have the same structure, the processing programs of the processes S33 and S35 for calculating the first and second luminance values using the equations (5) and (6) are also shared. Can be processed efficiently.

The present invention is not limited to the above embodiments.
For example, when determining the target color coordinates, in the above-described embodiment, the setting is made on the assumption that brightness is prioritized, but color reproduction may be set with priority. The gamma correction is not limited to γ = 2.2, and the LUT may be calculated with γ = 1.8 or the like.
By creating LUTs corresponding to a plurality of display modes in this way, LUTs corresponding to a plurality of display modes can be registered in the liquid crystal projector 1, and by manual selection by the user or automatic selection according to the type of image signal, The liquid crystal projector 1 can be set to an appropriate display mode.

The display device adjusted by the image quality adjustment method and the image quality adjustment device of the present invention is not limited to the transmission type three-plate liquid crystal projector 1, but may be a liquid crystal projection television, a liquid crystal projector using a direct view liquid crystal panel, and a liquid crystal It may be a display. Further, the display device is not limited to the display device using the liquid crystal panel 11 but may be a plasma television using a PDP or an organic EL display using an organic EL panel. In short, the present invention can be widely used for measurement of input / output characteristics for each display body and image quality adjustment of a display device using the measurement data.
Therefore, the display device of the present invention is not limited to a liquid crystal projector, and may be a liquid crystal projection television, a liquid crystal display, a plasma television, an organic EL display, or the like.
When a single liquid crystal panel, PDP, or organic EL panel provided with RGB pixels is used, the R, G, and B colors may be displayed in a single color and the color characteristics measured. .

1 is a block diagram illustrating a configuration of an image quality adjustment apparatus according to an embodiment. The block diagram which shows the structure of the image quality adjustment part of embodiment. 7 is a flowchart for explaining image quality adjustment processing. The flowchart for demonstrating an ideal color coordinate setting process. The flowchart for demonstrating a look-up table preparation process. The graph which shows the elementary color characteristic of each panel of RGB. The graph which shows the chromaticity coordinate of an ideal gray curve. The graph which shows the XYZ value of the ideal curve calculated from the ideal gray curve and the gamma characteristic. The graph explaining the 1st color characteristic calculation process of R panel. The graph explaining the 1st color characteristic calculation process of G panel. The graph explaining the 1st color characteristic calculation process of B panel. The graph explaining the 1st luminance value and 2nd color characteristic calculation process of R panel. The graph explaining the 1st luminance value and 2nd color characteristic calculation process of G panel. The graph explaining the 1st luminance value and 2nd color characteristic calculation process of B panel. The graph explaining the calculation process of the 2nd luminance value of R panel, and look-up table data. The graph explaining the calculation process of the 2nd luminance value of G panel, and look-up table data. The graph explaining the calculation process of the 2nd luminance value of B panel, and look-up table data. A graph showing a lookup table.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal projector, 2 ... Color luminance meter, 3 ... Image quality adjustment apparatus, 11 ... Liquid crystal panel, 12 ... Drive control part, 31 ... Measurement control part, 32 ... Image quality adjustment part, 33 ... Memory | storage part, 35 ... Target data setting Means 36: Look-up table creation means 37 ... Image quality adjustment means 311 ... Color characteristic measurement means 312 ... Color characteristic data processing storage means 331 ... Gamma correction data 332 ... Color characteristic data 333 ... LUT data 351 ... ideal gray curve creation means, 352 ... ideal curve color coordinate data creation means, 361 ... signal level setting means, 362 ... first color characteristic calculation means, 363 ... first luminance value calculation means, 364 ... second color Characteristic calculating means, 365... Second luminance value calculating means, 366... Look-up table data calculating means.

Claims (8)

A color characteristic measurement step of measuring display body color characteristic data including luminance values and color coordinate values for each of R, G, and B with respect to a drive signal level of the display body capable of displaying three colors of R, G, and B;
A target data setting step of setting color characteristic target data of an output image when a predetermined level of drive signal is input to the display body;
A lookup table creating step for creating a lookup table that defines a relationship between an input signal input to the display device having the display body and a drive signal input to the display body according to the input signal;
An image quality adjustment step of incorporating the created lookup table into the display device,
The lookup table creation step includes:
A signal level setting step for setting the signal level;
A condition in which the normalized luminance value of each of the RGB display body color characteristic data is equal to the luminance value corresponding to the input signal of the level set in the signal level setting step in the normalized luminance value of the color characteristic target data A first color characteristic calculation step for obtaining first color characteristic data for each of RGB satisfying
A first luminance value calculating step of calculating a first luminance value for each RGB from the first color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
A second color characteristic calculation step for obtaining second color characteristic data for each RGB satisfying a condition in which the normalized luminance value of each of the RGB display body color characteristic data satisfies the same condition as the first luminance value;
A second luminance value calculating step of calculating a second luminance value for each RGB from the second color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
The normalized luminance values of the display body color characteristic data for each RGB obtain the respective RGB drive signal levels that satisfy the condition equal to the second luminance value, and the signal levels input to the display device and the RGB A lookup table data calculation step for calculating lookup table data indicating a relationship with the drive signal level,
While changing the signal level in the signal level setting step, the first color characteristic calculation step, the first luminance value calculation step, the second color characteristic calculation step, the second luminance value calculation step, lookup table data A method for adjusting an image quality of a display device, wherein a lookup table is created by repeating the calculation step. The image quality adjustment method for a display device according to claim 1,
The target data setting step includes
An ideal gray curve creating step for creating an ideal gray curve indicating a change in chromaticity coordinates of an achromatic color with respect to an input signal in a display device;
An image quality adjusting method for a display device, comprising: an ideal curve color coordinate data creating step for creating ideal curve color coordinate data serving as color characteristic target data from gamma correction data in the display device and the ideal gray curve. In the image quality adjustment method of the display device according to claim 1 or 2,
In the first color characteristic calculation step, the normalized luminance value of each of the RGB display body color characteristic data has a level set in the signal level setting step in the normalized luminance value of the color characteristic target data. First R color tristimulus values (Xrt, Yrt, Zrt), G first tristimulus values (Xgt, Ygt, Zgt) and B color first conditions satisfying the same condition as the luminance value corresponding to the input signal Find the tristimulus value of 1 (Xbt, Ybt, Zbt)
In the first luminance value calculation step, the first color characteristic data for each RGB is obtained from the RGB color characteristic data calculated in the first color characteristic calculation step and the color characteristic target data corresponding to the set input signal level. Calculate luminance values (Yr, Yg, Yb)
In the second color characteristic calculation step, the second color of R color satisfying the condition that the normalized luminance value of each of the RGB display body color characteristic data is equal to the first luminance value (Yr, Yg, Yb). Tristimulus values (Xrt ', Yrt', Zrt '), G color second tristimulus values (Xgt', Ygt ', Zgt'), B color second tristimulus values (Xbt ', Ybt') , Zbt ')
In the second luminance value calculation step, a second color value for each RGB is calculated from each color characteristic data of RGB calculated in the second color characteristic calculation step and color characteristic target data corresponding to the set input signal level. Luminance values (Yr ′, Yg ′, Yb ′) are calculated. The image quality adjustment method for a display device according to claim 3,
When the tristimulus value of the color characteristic target data corresponding to the input signal at the level set in the signal level setting step in the color characteristic target data is (X, Y, Z) and black is displayed on the display device When the tristimulus values of (Xbk, YbK, Zbk) are
In the first luminance value calculating step, the first luminance value (Yr, Yg, Yb) is

In
In the second luminance value calculating step, the second luminance value (Yr ′, Yg ′, Yb ′) is

A method for adjusting the image quality of a display device, characterized in that: The image quality adjustment method for a display device according to any one of claims 1 to 4,
An image quality adjusting method for a display device, wherein the display device is a three-plate type liquid crystal projector having three liquid crystal panels for RGB as a display body. Color characteristic measuring means for measuring display body color characteristic data including luminance values and color coordinate values for each of R, G, and B with respect to a drive signal level of a display body capable of displaying three colors of R, G, and B;
Target data setting means for setting color characteristic target data of an output image when a predetermined level of drive signal is input to the display body;
Lookup table creating means for creating a lookup table that defines a relationship between an input signal input to the display device having the display body and a drive signal input to the display body according to the input signal;
Image quality adjustment means for incorporating the created lookup table into the display device,
The lookup table creation means includes:
Signal level setting means for setting the signal level;
A condition in which the normalized luminance value of each of the RGB display body color characteristic data is equal to the luminance value corresponding to the input signal of the level set by the signal level setting means in the normalized luminance value of the color characteristic target data First color characteristic calculation means for obtaining first color characteristic data for each of RGB satisfying
First luminance value calculating means for calculating a first luminance value for each RGB from the first color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
Second color characteristic calculation means for obtaining second color characteristic data for each RGB satisfying a condition in which normalized luminance values of the respective RGB display body color characteristic data are equal to the first luminance value;
Second luminance value calculation means for calculating a second luminance value for each RGB from the second color characteristic data for each RGB and the color characteristic target data corresponding to the set signal level;
The normalized luminance values of the display body color characteristic data for each RGB obtain the respective RGB drive signal levels that satisfy the condition equal to the second luminance value, and the signal levels input to the display device and the RGB Lookup table data calculating means for calculating lookup table data indicating the relationship with the drive signal level;
While changing the signal level by the signal level setting means, the first color characteristic calculating means, the first luminance value calculating means, the second color characteristic calculating means, the second luminance value calculating means, look-up table data An image quality adjustment device for a display device, wherein a lookup table is created using a calculation means. A display capable of displaying three colors of R, G and B;
A drive control circuit unit for driving the display body;
6. A display device, wherein the drive control circuit unit controls driving of the display body using a look-up table created by the image quality adjustment method for a display device according to any one of claims 1 to 5. . The display device according to claim 7,
A display device comprising a three-plate liquid crystal projector having three liquid crystal panels for RGB as the display body.

Images