JP5651419B2 - Correction method, display device, and computer program - Google Patents

Description

  The present invention relates to a correction method for correcting luminance unevenness and color unevenness by correcting the intensity of each color component of an image of a plurality of pixels according to the characteristics of a display device. In particular, the present invention relates to a correction method that can appropriately correct luminance unevenness and color unevenness regardless of the color balance setting in the display device, a display device that implements the correction method, and a computer program that causes a computer to execute the correction method.

  Display devices such as LCD (Liquid Crystal Display) monitors, PDP (Plasma Display Panel) monitors, and organic EL (Electro Luminescence) monitors are liquid crystal panel characteristics of individual products if they are LCD monitors, and each element if they are PDP monitors. Due to the light emission characteristics, spatial luminance unevenness and color unevenness occur in the screen area.

  As a conventional correction method for luminance unevenness, the brightness level of the peripheral portion generally tends to be lower than that of the central portion of the screen area in the display device. Therefore, the luminance level of the central portion is changed to the luminance level of the peripheral portion. Patent Document 1 discloses a method for reducing the amount correspondingly. Specifically, the screen area is divided into a plurality of areas, an image signal with a uniform luminance gradation value is input to the entire screen, and the luminance of each area of the actual display screen is measured. When the target luminance is set as the target luminance, a correction amount for correcting the luminance gradation value of the other region is obtained in advance for each region. Further, the actual luminance is measured in the same manner by changing the gradation value of the uniform luminance to be input step by step, and the correction amount for each area is obtained for each gradation value. By storing the calculated correction amount for each gradation value and for each area, the luminance gradation value of each pixel is corrected based on the correction amount when displaying an actual image, and the luminance of the central portion It is possible to suppress luminance unevenness by adjusting the level to the same luminance level as the peripheral portion.

  As for the correction method for color unevenness, the spatial nonuniformity of the color components, for example, the characteristic that the red component is displayed strongly on the left side of the screen is determined for each color component in advance. A technique is disclosed in which a correction amount that cancels out is stored in a storage unit, and correction is performed using the correction amount for each color component when an image is displayed (Patent Document 2).

  Although these conventional brightness unevenness correction methods can suppress the brightness unevenness, the brightness level of the entire screen is lowered because the brightness level of the central portion is lowered so that the brightness levels of the peripheral portions are the same. Therefore, it is difficult to apply these correction methods to a display device that requires high luminance. Color unevenness correction can also be realized by applying the above-described conventional correction method for luminance unevenness to the intensity of each color component. By obtaining and storing a correction amount for the intensity for each color component in advance and correcting each intensity based on the correction amount, it is possible to make the color uniform over the entire screen. However, in this case as well, the intensity of each color component is corrected so as to be aligned in a low intensity area for each area, resulting in a decrease in the luminance level of the entire screen.

  Therefore, the inventors store a correction coefficient that decreases the degree of correction as the intensity increases according to the intensity of each color component, and multiplies the correction amount stored in advance by the correction coefficient to each color component. In addition, a correction method has been proposed that appropriately corrects luminance unevenness and color unevenness while maintaining high luminance by providing an inclination so as to reduce the correction amount when the intensity is high (Patent Document 3).

JP 2007-114427 A JP-A-5-197357 JP 2008-310261 A

  However, the technique disclosed in Patent Document 3 was created on the premise that the maximum intensity for each color component at each set color temperature is not corrected, and the degree of correction is increased when the intensity is relatively low. This is effective when the correction amount is stored in advance. Accordingly, when using a correction amount obtained by a different method or a correction amount added with another method, luminance unevenness and color unevenness cannot always be corrected appropriately.

  In addition, the technique disclosed in Patent Document 3 assumes a unique color balance according to the set color temperature, and stores a correction amount and a correction degree in association with each intensity of each color component in each color balance. I used it. Therefore, the correction amount and the correction degree corresponding to an arbitrary intensity of one color component are specified. At this time, depending on the balance of intensity for each color component of the image signal to be corrected, correction of luminance unevenness and color unevenness may be insufficient.

  Further, the luminance unevenness and color unevenness of the display change according to the brightness (brightness) setting of the display device. However, since the technique disclosed in Patent Document 3 does not take into account changes in brightness settings, even if brightness unevenness and color unevenness can be corrected appropriately with predetermined brightness settings such as initial settings, other than this, In some brightness settings, correction was insufficient.

  The present invention has been made in view of such circumstances, and stores luminance information regarding luminance measurement values for each color component, not a correction amount assuming a specific color balance, and is the same as the specific color balance. The correction amount is calculated according to various color balances at the time of display, and when calculating the correction amount, the correction coefficient indicating the same correction degree as a whole is used for each color component. , A correction method that can more effectively correct luminance unevenness and color unevenness according to various color balances such as setting the color temperature of the display screen, a display device that implements the correction method, and a computer that performs the correction It is an object to provide a computer program for executing a method.

  Another object of the present invention is to use the degree of correction at the highest intensity among the intensities for each color component for the intensity of each color component, thereby suppressing the decrease in luminance due to correction and maintaining the luminance. An object of the present invention is to provide a correction method capable of more appropriately correcting unevenness and color unevenness.

  Another object of the present invention is to provide a correction method capable of suppressing color unevenness more accurately for each color component by using a ratio to a luminance measurement value in a central region for each color component.

  Another object of the present invention is to store a luminance change characteristic with respect to a change in brightness setting, and correct luminance information based on the brightness setting and the change characteristic when correcting luminance unevenness and color unevenness. Another object of the present invention is to provide a correction method, a display device, and a computer program capable of correcting appropriate luminance unevenness and color unevenness even when the brightness setting is changed.

In the correction method according to the present invention, when an image composed of a plurality of pixels is displayed on a display screen, the intensity for each color component corresponding to each pixel of the image is represented in the display screen on which the pixel is displayed. In the correction method for correcting according to the position and the intensity, the brightness when an image having a single intensity is displayed on the display screen is measured for each of a plurality of areas constituting the display screen, and the measured brightness First luminance information for each color component and each region based on the image, second luminance information for each region based on the measured luminance, and a correction coefficient corresponding to each of a plurality of intensities, and storing the image on the display screen The first luminance information for each color component of the area corresponding to the position of the pixel on the display screen, the second luminance information of the area, and the maximum intensity of the color component of each pixel of the image Read correction coefficient corresponding to The intensity of each color component of each pixel of the image, read the first luminance information, and correcting based on the second luminance information, and the correction coefficient.

In the correction method according to the present invention, when an image composed of a plurality of pixels is displayed on a display screen, the intensity for each color component corresponding to each pixel of the image is represented in the display screen on which the pixel is displayed. In the correction method for correcting according to the position and the intensity, when displaying an image on the display screen, first luminance information for each of a plurality of areas and color components constituting the display screen stored in advance, The second luminance information for each of a plurality of areas constituting the display screen and a correction coefficient corresponding to each of a plurality of intensities are read, and the intensity for each color component of each pixel of the image is determined on the position of the pixel on the display screen. Correction is performed based on the first luminance information for each color component of the region corresponding to, the second luminance information of the region, and a correction coefficient corresponding to the maximum intensity of the color component.

In the correction method according to the present invention, the first luminance information is a ratio for each color component between a luminance measurement value at a specific position in the display screen and a luminance measurement value in each of the plurality of regions. And

In the correction method according to the present invention, the second luminance information is a ratio of the luminance in each of the plurality of regions to the luminance in the specific region when displaying an image whose intensity for each color component is a specific value. When the image is displayed on the display screen, the correction coefficient corresponding to the intensity of each color component corresponding to each pixel of the image and the second luminance information of the area corresponding to the position of the pixel are added. , Multiplying the addition result by the first luminance information corresponding to the intensity for each color component, subtracting the multiplication result from an arbitrary reference value, and multiplying the intensity for each color component by a value based on the subtraction result Correction.

According to the correction method of the present invention, the brightness at the time of displaying an image on the display screen can be changed, the stored first luminance information is corrected according to the brightness at the time of display, and the image The intensity of each color component of each pixel is corrected based on the corrected first luminance information, the second luminance information, and the correction coefficient.

In the correction method according to the present invention, a basic characteristic of a change in luminance with respect to brightness is determined in advance for each region, and an image having a predetermined intensity is displayed on the display screen with at least two brightnesses for each region. The brightness when displayed is measured, and the change characteristic of the brightness with respect to brightness is calculated for each region according to the measured brightness and the basic characteristic, and the calculated change characteristic is stored, When the first luminance information is corrected, the first luminance information is corrected based on the brightness at the time of display and the stored change characteristics.

In the correction method according to the present invention, the basic characteristic is a characteristic approximated by a linear function or a quadratic function whose coefficient is undetermined, and the calculation of the change characteristic is performed on brightness measured at at least two brightness levels. Accordingly, the calculation is performed by calculating the coefficient of the linear function or the quadratic function.

The correction method according to the present invention is characterized in that the at least two brightnesses include a maximum brightness.

The display device according to the present invention has a display screen, and when displaying an image composed of a plurality of pixels on the display screen, the pixels are displayed with the intensity for each color component corresponding to each pixel of the image. In a display device comprising correction means for correcting according to the corresponding position in the display screen and the intensity, the color component based on the luminance measurement value for each of the plurality of areas constituting the display screen and the first for each area. 1 luminance information, second luminance information for each area based on the luminance measurement value, and a storage unit storing correction coefficients corresponding to each of a plurality of intensities, and a position of each pixel of an image to be displayed Means for reading out the first luminance information for each color component of the region, the second luminance information of the region, and a correction coefficient corresponding to the maximum intensity of the color component of each pixel from the storage unit, Is the color at each pixel The intensity of each minute, the read first luminance information, characterized in that are so corrected that based on the second luminance information, and the correction coefficient.

The display device according to the present invention is capable of changing the brightness at the time of displaying an image on the display screen, and the storage unit stores a luminance change characteristic with respect to the brightness, and the brightness at the time of display. And correcting means for correcting the read first luminance information based on the stored change characteristics, wherein the correcting means corrects the intensity of each color component in each pixel by the correcting means. Correction is performed based on the luminance information, the second luminance information, and the correction coefficient.

A computer program according to the present invention provides a computer having means for outputting an image signal to an image display means, and displays a single intensity image on the display screen for each of a plurality of areas constituting the display screen of the image display means. A first ratio for each color component between a luminance measurement value in a specific area when displayed and a luminance measurement value in each of the plurality of areas, and an identification when displaying an image whose intensity for each color component is a specific value The computer program for correcting the intensity of the color component corresponding to each pixel included in the image signal using the second ratio of the luminance in each of the plurality of areas to the luminance in the area and the correction coefficient corresponding to each of the plurality of intensities a is a computer, with respect to the intensity of each color component corresponding to each pixel of an image representing an image signal output from, said correction coefficient corresponding to the maximum intensity of the color components, before The step of adding the second ratio of the region corresponding to the pixel position, the step of multiplying the addition result by the first ratio corresponding to the intensity for each color component, and subtracting the multiplication result from an arbitrary reference value And a step of multiplying the intensity of each color component corresponding to each pixel of the image represented by the output image signal by the subtraction result.

The computer program according to the present invention further includes a step of correcting the first ratio based on the brightness and the change characteristic, further using a luminance change characteristic with respect to the brightness when displaying the image on the display screen. It is made to perform.

  In the present invention, intensity information for each color component of an image composed of a plurality of pixels is associated with the intensity and each of a plurality of areas constituting the image, and luminance information based on a luminance measurement value is stored for each color component. In addition, at the time of correction, luminance information is read and a correction amount is obtained and used. The present invention does not perform correction based on the stored correction amount, but uses the luminance information based on the stored luminance measurement value to calculate the correction amount and use it for correction. Note that the luminance is measured as information unique to the display panel in a test process after the display panel is assembled. In addition, a correction coefficient indicating a correction degree is stored in order to increase the correction degree as the intensity is low and to reduce the correction degree so as not to reduce the intensity unnecessarily when the intensity is high. A correction amount is obtained together with the information to perform correction.

  In the present invention, the intensity of each color component may be represented by a gradation value. The image may be a color image or a monochrome image. Even in a monochrome image, the intensity balance for each color component varies depending on the color balance setting. Even in the case of a monochrome image, the occurrence of uneven brightness and uneven color can be prevented regardless of the color balance setting.

  In the present invention, the correction degree of the intensity of each color component is adjusted using a correction coefficient corresponding to the maximum intensity of each color component. This avoids unnecessary adjustment of the intensity of the high-intensity component and also uses the same correction coefficient for different color components to avoid unnecessary correction of color balance.

  In the present invention, the luminance information based on the luminance measurement value uses a ratio for each color component between the luminance measurement value at a specific position in the display screen and the luminance measurement value in each of the plurality of regions. As the specific position, a central area where the luminance is relatively high on the display screen is used. More specifically, the ratio of luminance in other areas based on the luminance in the central area when the display screen is divided vertically and horizontally is measured and stored for each color component. Since the inherent luminance distribution in the raw state of the display panel is used, there is no change even for an image signal having an arbitrary color balance.

  In the present invention, the luminance of the display panel when an image having a specific intensity for each color component is displayed is measured, and the ratio of the luminance in each region to the luminance in a specific region (preferably the center having the highest luminance). Is stored and used for correction together with the above-described luminance information (ratio for each color component) and correction coefficient. At this time, for example, a white image having the maximum intensity is used as the image whose intensity for each color component is a specific value. Thereby, the luminance used for correction can be obtained with high accuracy. Furthermore, in the present invention, the result of adding the correction coefficient corresponding to the intensity for each color component corresponding to each pixel of the image and the luminance unevenness amount in the pixel is multiplied by the ratio for each color component, and each color component is obtained. Correction is performed using a value based on a result obtained by subtracting each multiplication result from an arbitrary reference value. Since the correction amount is calculated and used for each color component using the luminance characteristics of the panel for each color component, the color balance of the image before correction is not lost.

When the input video level is the maximum (the gradation value of the input image signal is the maximum), the unevenness correction is performed by correcting the high luminance area to the low luminance area. For this reason, when unevenness correction is performed, the maximum luminance and contrast ratio characteristics of the display screen are degraded. That is, reducing the unevenness and maintaining the maximum luminance and contrast ratio are in a trade-off relationship. Which one of priority should be given to the reduction of unevenness and the maintenance of the maximum luminance and the contrast ratio varies depending on the type of image to be displayed, the usage mode of the display device, and the like. However, when the brightness is set high, it is estimated that the user demands a display with high brightness and high contrast, and when the brightness is set low, the display with high brightness and high contrast is not required. Presumed.
Therefore, in the present invention, a plurality of different brightness unevenness amounts are stored for a plurality of brightness settings, and the brightness unevenness amount corresponding to the brightness setting at the time of display is added to the correction coefficient. As a result, the degree of unevenness correction can be adjusted according to the brightness setting.

  In the present invention, the stored luminance information is corrected according to the brightness setting at the time of display, the correction amount is calculated using the corrected luminance information and the correction coefficient stored in advance, and used for correction. Thereby, it is possible to realize an appropriate unevenness correction even when the brightness setting is changed.

The inventor of the present application has found that the characteristic of the change in luminance with respect to the change in brightness setting substantially depends on the display position of the display screen. Therefore, in the present invention, the basic characteristic of the change in luminance with respect to the brightness setting is determined in advance for each area of the display screen. Since the basic characteristics of each region have little difference between display devices, the basic characteristics need not be determined for each display device, but may be stored in advance at the design stage of the display device.
Then, in the display device manufacturing process or test process, etc., brightness measurement is performed with at least two brightness settings, and detailed change characteristics of each region are calculated according to the measured brightness and the previously stored basic characteristics. Remember. By using the stored change characteristic, the luminance information can be corrected according to the brightness setting.

In the present invention, the basic characteristic of the luminance change with respect to the brightness setting is a characteristic approximated as a linear function or a quadratic function whose coefficient is undetermined. Thereafter, the coefficient of the basic characteristic is calculated according to the result of the luminance measurement in the manufacturing process or the test process, and the linear function or the quadratic function with the fixed coefficient is stored as the change characteristic.
The coefficient of the linear function or the quadratic function is about 2 to 3, and the coefficient can be calculated by performing luminance measurement with about 2 to 3 brightness settings.

  In the present invention, the brightness measurement brightness setting performed in the manufacturing process or test process of the display device includes a setting with the maximum brightness. This makes it possible to calculate the luminance change characteristic with respect to the brightness setting with high accuracy.

  In the present invention, the basic characteristic of the luminance change with respect to the brightness setting is determined in advance for each of a plurality of areas constituting the display screen, and the luminance is measured with at least two brightness settings in the manufacturing process or the test process of the display device. Then, the luminance change characteristic with respect to the brightness setting is calculated and stored from the measurement result and the basic characteristic. When performing image display, the intensity for each color component of each pixel of the image is corrected based on the change characteristic corresponding to the display position and the correction coefficient stored in advance. Thereby, it is possible to realize an appropriate unevenness correction even when the brightness setting is changed.

  According to the present invention, information on the luminance distribution for each color component specific to each display panel obtained by actual measurement without measuring and storing the correction amount for each intensity and area necessary for each color temperature setting in advance. Therefore, the luminance unevenness and the color unevenness can be corrected while maintaining the color balance of the input image signal as well as the color temperature. Therefore, it is possible to correct luminance unevenness and color unevenness according to various color balances.

  Further, according to the present invention, the luminance change characteristic with respect to the brightness setting is calculated and stored in advance from the measurement result of the basic characteristic and the luminance of each region, and according to the brightness setting at the time of display and the stored change characteristic, By correcting the luminance information used for calculating the correction amount, it is possible to correct luminance unevenness and color unevenness according to various brightness settings.

It is a block diagram which shows the structure of the display apparatus which concerns on this invention. 6 is an explanatory diagram illustrating an example of the content of unevenness stored in the LUT of the display device in Embodiment 1. FIG. 6 is an explanatory diagram illustrating an example of the contents of correction coefficients stored in a register of the display device in Embodiment 1. FIG. 6 is an explanatory diagram illustrating an example of the content of luminance measurement value information for each color component stored in the LUT of the display device according to Embodiment 1. FIG. It is explanatory drawing which shows typically the process which calculates | requires the luminance measurement value information for every color component. FIG. 5 is an explanatory diagram conceptually illustrating a process of performing correction using the unevenness amount, the correction coefficient, and the luminance measurement value information for each color component illustrated in the explanatory diagrams of FIGS. 2 to 4. 6 is a flowchart illustrating an example of a correction processing procedure executed by the unevenness correction unit of the display device according to the first embodiment. It is a block diagram which shows the structure in the case of implementing the correction method which concerns on this invention with a computer apparatus. It is a schematic diagram for demonstrating the change of the brightness nonuniformity with respect to the change of brightness setting. It is the model which showed the luminance change with respect to the change of a brightness setting according to the area | region of the display screen. 14 is a flowchart for explaining a procedure of processing performed before the factory shipment of the display device for unevenness correction according to the third embodiment. 14 is a flowchart illustrating a procedure of processing performed when the display device according to Embodiment 3 changes brightness settings. It is a schematic diagram for demonstrating the relationship between the degree of nonuniformity correction, maximum luminance, and contrast ratio. 15 is a flowchart illustrating a procedure of processing performed when the display device according to Embodiment 4 changes the brightness setting.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a display device according to the present invention. The display device 1 includes an input unit 11 that is an interface that receives an input of an image signal from an image signal output device 2 to be described later, a conversion unit 12 that appropriately converts gradation values representing the intensity of each color component represented by the image signal, Display unit 15 including unevenness correction unit 13 that corrects brightness unevenness and color unevenness, output unit 14 that outputs corrected gradation values to display unit 15, LCD panel, PDP panel, and the like, and a drive circuit that drives them. And an LUT (Look Up Table) 16 in which each information is stored and which can be referred to from the conversion unit 12 and the unevenness correction unit 13, a register 17, and an operation unit 18 that accepts a display setting operation by the user. I have. The conversion unit 12, the unevenness correction unit 13, the output unit 14, the LUT 16, and the register 17 are configured by an ASIC (Application Specific Integrated Circuit).

  The image signal output device 2 is a device that outputs image signals of a PC (Personal Computer), a TV tuner, a DVD (Digital Versatile Disc) player, a game machine, and the like. The display device 1 receives the image signal output from the image signal output device 2 by the input unit 11 and corresponds to the display unit 15 based on each color component of each pixel represented by the image signal or the gradation values of luminance and color difference. An image signal is output by the output unit 14 and an image is displayed on the display unit 15.

  In the conversion unit 12 and the unevenness correction unit 13, color balance (for example, color temperature) and luminance are controlled by a control signal from the image signal output device 2 or a control signal received via the operation unit 18 provided in the display device 1 itself. Or a setting such as resolution is accepted. The conversion unit 12 reads parameters and the like corresponding to the settings received by the control signal from the LUT 16. Thereby, the conversion part 12 is made to perform the process according to a setting.

  In the conversion unit 12, the color component of each pixel constituting the image displayed on the display unit 15 is represented by R (Red: red component) G (Green: green component) B (Blue: blue component), and each of the RGB An input of RGB signals of 8 bits, that is, 24 bits representing the gradation values (R, G, B) in 256 steps from 0 to 255, is accepted. The input unit 11 may have an analog / digital conversion function, a function of converting to an RGB signal, or the like depending on the type of image signal to be received. The image signal received by the conversion unit 12 is not limited to the 24-bit RGB signal as described above, and may include a signal including other color components. Further, depending on the conversion process, for example, each color component may be 10 bits, 12 bits, or An image signal represented by 16 bits or the like may be used.

  Then, the conversion unit 12 appropriately converts the gradation value of each color component input via the input unit 11 and outputs it. A plurality of coefficients (color matrix) for color space conversion are prepared in the conversion unit 12. The conversion unit 12 performs conversion on the input gradation value of each input color component using a coefficient corresponding to the control signal from the image signal output device 2 or the control signal received by the operation unit 18. The coefficients prepared in the conversion unit 12 include coefficients for converting the input gradation values R, G, and B so that the intensity ratios according to the color balance settings are obtained. .

  For example, when the conversion unit 12 receives input of RGB signals represented by 256-level gradation values from 0 to 255, the maximum gradation values (Tr, Tg, Tb) with color temperatures of R, G, and B, respectively. ) = (255, 192, 128), the gradation values of the input RGB components are set to (1 (= 255/255), 0.75 (= 192/255), 0 .5 (= 128/255)) to change the ratio. In this case, when the gradation value of the input RGB component is (R, G, B) = (192, 170, 128), the conversion unit 12 (R ′, G ′, B ′) = (192). , 128, 64).

  The unevenness correction unit 13 corrects luminance unevenness and color unevenness and outputs the gradation values (R ′, G ′, B ′) of the respective color components output from the conversion unit 12. The reason why the unevenness correction unit 13 is arranged after the conversion unit 12 is that it is necessary to perform unevenness correction after the color space has been converted. The unevenness correction unit 13 calculates brightness measurement value information stored in an LUT 16 (to be described later) and unevenness amount based on the center brightness and a correction degree stored in the register 17 in order to implement the correction method according to the present invention. The indicated correction coefficients are read out and used for correction. Details of the unevenness correction will be described later.

  The LUT 16 stores a non-uniformity amount based on the center luminance used by the non-uniformity correction unit 13 and luminance measurement value information for each color component. The register 17 stores a correction coefficient corresponding to the gradation value. In the present invention, an input image signal that does not apply to the discrete gradation values is stored by storing measured luminance measurement value information instead of the correction amount obtained for each discrete gradation value in advance. Effectively corrects luminance unevenness and color unevenness.

  FIG. 2 is an explanatory diagram illustrating an example of the content of the unevenness amount stored in the LUT 16 of the display device 1 according to the first embodiment. The explanatory diagram of FIG. 2 shows the amount of unevenness based on the luminance reduction rate of each region with the luminance of the center region as a reference when a single color (white) image signal is input to the entire screen. The amount of unevenness is a uniformity measurement device (luminance measurement device) that is a distribution of luminance values when a single color image signal as described above is actually input in the test step after the assembly step in the process of manufacturing the display device 1. Is measured using and written in the LUT 16.

  In the explanatory diagram of FIG. 2, when a single color image signal corresponding to a luminance gradation value of 255 is input to the entire screen, the amount of unevenness in the region A1 is 85.3%, and the amount of unevenness in the region A2 is Similarly, it is shown to be 93.0%. In addition, when a single color image signal having a luminance gradation value corresponding to 224 is input to the entire screen, the amount of unevenness in the region A1 is 90.6%, and the amount of unevenness in the region A2 is 95.0%. It has been shown.

  The unevenness correction unit 13 performs unevenness when the gradation value of the luminance corresponding to the gradation value of each input color component is 255 and the gradation value of the luminance is the gradation value of the pixels included in the area A1. Read that the amount is 85.3%. The unevenness amount of 85.3% is a measured value (unevenness amount) that when displayed on the display unit 15 as it is, the luminance level in the area A1 is 85.3% based on the luminance of the center area. Therefore, it is shown that it is necessary to correct each gradation value of each color component in order to correct the luminance corresponding to the difference from the center luminance.

  FIG. 3 is an explanatory diagram illustrating an example of the contents of the correction coefficient stored in the register 17 of the display device 1 according to the first embodiment. The correction coefficient is a coefficient for adjusting the degree of correction according to the maximum gradation value MAX (R ′, G ′, B ′) of the input gradation values R ′, G ′, B ′. Yes, and stored in association with the gradation value. In the example shown in the explanatory diagram of FIG. 3, when the maximum gradation value MAX (R ′, G ′, B ′) among the input gradation values R ′, G ′, B ′ is 255, the correction coefficient Is 0%, and when the maximum gradation value MAX (R ′, G ′, B ′) is 254, the correction coefficient is similarly 0.125%. As the maximum gradation value MAX (R ′, G ′, B ′) decreases, the correction coefficient increases. When the maximum gradation value MAX (R ′, G ′, B ′) is zero, the correction coefficient Is 100%. Note that when the maximum gradation value MAX (R ′, G ′, B ′) is 128, the correction coefficient reaches 100%, and it is assumed that the correction coefficient is 100% until 128 or less is zero. The decreasing tendency of the correction coefficient with respect to the maximum gradation value MAX (R ′, G ′, B ′) may not be linear. Also, correction coefficients may be stored in association with representative values for every 32 gradations instead of all gradation values, and intermediate gradation values may be obtained by linear interpolation.

  FIG. 4 is an explanatory diagram illustrating an example of the content of the luminance measurement value information for each color component stored in the LUT 16 of the display device 1 according to the first embodiment. In the explanatory diagram of FIG. 4, a single color luminance value of each color component is obtained based on a luminance measurement value when a single color (white) image signal is input to the entire screen, and the center is obtained for each color component (R, G, B). The ratio between the monochromatic luminance of the area and the monochromatic luminance of each area is shown for each area.

  In the explanatory diagram of FIG. 4, the ratio of the R component in the region A1 is 1.17, and the ratio of the R component in the region A2 is 1.07. In addition, the ratio of the G component in the area A1 is 1.13, the ratio of the R component in the area A2 is 1.07, the ratio of the B component in the area A1 is 1.13, and the ratio of the B component in the area A2 is It is shown to be 1.04.

  The monochromatic luminance value is a value that can be obtained by distributing luminance measurement values when a white image signal is input. The luminance measurement value information uses the uniformity measurement device (luminance measurement device) to determine the distribution of luminance values when the single-color image signal is actually input in the test process after the assembly process, as with the unevenness amount. The above ratio is obtained and written in the LUT 16.

FIG. 5 is an explanatory diagram schematically showing a process of obtaining luminance measurement value information for each color component. In the upper left part of FIG. 5 is a luminance value distribution obtained by measurement when an image signal representing white is input (for example, R, G, B = 255, 255, 255). As shown in FIG. 5, in the center region ^{100cd / m 2, 50cd / m} 2 in the region A1, and was in the region A2 60cd / m ^2.

Here, the white luminance measurement value is the sum of the luminance values of the RGB color components. As shown on the right side of FIG. 5, the luminance 100 cd / m ² of the white center region is, for example, 100 = R20 + G70 + B10. The same applies to areas other than the center area. The luminance 50 cd / m ² of the area A1 is 50 = R15 + G30 + B5, and the luminance 60 cd / m ² of the area A2 is 60 = R18 + G34 + B8. The luminance measurement value obtained for each region in this manner is decomposed into luminance values for each color component, and a ratio obtained by dividing the center luminance value by the luminance value in each region is obtained for each color component and stored in the LUT 16. .

  FIG. 6 is an explanatory diagram conceptually showing a process of performing correction using the unevenness amount, the correction coefficient, and the luminance measurement value information for each color component shown in the explanatory diagrams of FIGS. As shown on the left side in FIG. 6, when the gradation values R ′, G ′, and B ′ for each color component of a certain pixel are input, the unevenness correction unit 13 performs the center area of the pixel for each color component. The luminance ratio with respect to the luminance is read out from the LUT 16.

  The unevenness correction unit 13 reads from the LUT 16 a correction coefficient corresponding to the maximum gradation value MAX (R ′, G ′, B ′) among the gradation values R ′, G ′, B ′ for each color component. The unevenness correction unit 13 further reads out from the LUT 16 the unevenness amount in the pixel corresponding to the maximum gradation value MAX (R ′, G ′, B ′). Then, the read correction coefficient and the amount of unevenness are linearly added to calculate the amount of unevenness of each area to be obtained from the actually measured luminance unevenness or color unevenness (unevenness amount). Then, the unevenness correction unit 13 multiplies the luminance ratio for each color component by the unevenness amount obtained by calculation to obtain an optimal correction amount for RGB balance, and obtains a gradation value for each color component of the input image signal. Then, correction is performed using the obtained correction amount, and output from the output unit 14.

  Next, a process of performing correction using the unevenness amount, the correction coefficient, and the luminance measurement value information for each color component shown in the explanatory diagram of FIG. 6 will be described in detail with reference to a flowchart. FIG. 7 is a flowchart illustrating an example of a correction processing procedure executed by the unevenness correction unit 13 of the display device 1 according to the first embodiment. The unevenness correction unit 13 performs the following processing on the gradation value of each pixel of the converted image signal output from the conversion unit 12.

  The unevenness correction unit 13 obtains the maximum gradation value MAX (R ′, G ′, B ′) among the gradation values R ′, G ′, B ′ for each color component in an input pixel (step S1). ). The unevenness correction unit 13 reads the correction coefficient corresponding to the maximum gradation value MAX (R ′, G ′, B ′) obtained in step S1 from the register 17 (step S2). Next, the unevenness correction unit 13 uses the maximum gradation value MAX (R ′, G ′, B ′) based on the maximum gradation value MAX (R ′, G ′, B ′). , G ′, B ′), the amount of unevenness (luminance reduction rate) in each region is read from the LUT 16 (step S3).

  The unevenness correction unit 13 adds the correction coefficient read in step S2 and the unevenness amount read in step S3 to the gradation values R ′, G ′, and B ′ for each color component of the input pixel. Then, the amount of unevenness that should be targeted for each color component is calculated (step S4).

  Next, the unevenness correction unit 13 reads out, from the LUT 17, the ratio between the monochrome luminance in the pixel and the monochrome luminance in the center area for each of the gradation values R ′, G ′, B ′ for each color component of the input pixel ( Step S5). The unevenness correction unit 13 multiplies the target unevenness amount calculated in step S4 by the ratio read in step S5 (step S6), subtracts the multiplication result from the reference value, and determines the color for each color component. A correction amount considering the balance is calculated (step S7).

The calculation process from step S5 to step S7 is expressed by the following equation (1). Note that any one of R, G, and B is applied to the capital letter X, and correction amounts of each color component in the region (x, y), Correct_R _{(x, y)} , Correct_G _{(x, y)} , Correct_B _{(x, y)} is required.

  The unevenness correction unit 13 multiplies the input gradation values R ′, G ′, and B ′ by the correction amount for each color component calculated in step S <b> 7 (step S <b> 8). The unevenness correction unit 13 thereby ends the correction process and outputs the input gradation value of each pixel to the output unit 14.

  The processing procedure shown in FIG. 7 will be described with a specific example. At this time, the unevenness amount, correction coefficient, and luminance ratio shown in FIGS. 2 to 4 are used. As a specific example, a case where the converted gradation value input from the conversion unit 12 is (R ′, G ′, B ′) = (255, 192, 128) will be described. The gradation values R ′, G ′, and B ′ are assumed to be the gradation values of the pixels included in the area A1 in the explanatory diagrams of FIGS.

  In step S <b> 1, the unevenness correction unit 13 determines that the maximum gradation value MAX (R ′, G ′, B ′) for each color component is “255”. In step S <b> 2, the unevenness correction unit 13 reads a correction coefficient corresponding to the gradation value 255 from the register 17. Referring to FIG. 3, the correction coefficient indicating the degree of correction when the maximum gradation value is “255” is “0 (%)”. In step S3, the unevenness correction unit 13 calculates the unevenness amount “85.3 (%)” in the area A1 when the gradation value for each color component is the maximum gradation value 255 of the input gradation value. Read (see FIG. 2).

  In step S4, the unevenness correction unit 13 adds the correction coefficient “0 (%)” read out in step S2 and the correction coefficient “85.3 (%)” read out in step S3. The amount of unevenness “85.3 (%)” to be calculated is calculated.

In step S <b> 5, the unevenness correction unit 13 determines, for each of the gradation values R ′, G ′, and B ′ for each input color component, the ratio of the monochrome luminance in the region A <b> 1 corresponding to the pixel and the monochrome luminance in the center region Are read from the LUT 16. Specifically, the unevenness correction unit 13 compares the ratio of each color component stored in the LUT 16 (monochromatic luminance Lv_X _{center in the center} region / monochromatic luminance Lv_X (x, y) in the region _{(x, y)} ) “R: 1. .17, G: 1.13, B: 1.13 ".

  In step S6, the unevenness correction unit 13 compares the color component ratios R: 1.17, G: 1.13, and B: 1.5 to the correction amount “85.3 (%)” that should be the target calculated in step S4. 13 is multiplied to obtain “99.8 (%), 96.4 (%), 96.4 (%)”. Further, in step S7, the unevenness correction unit 13 subtracts “99.8 (%), 96.4 (%), 96.4 (%)” of the multiplication results from the reference value 100 (%), respectively, for each color component. A correction amount “0 (%), 3.6 (%), 3.6 (%)” considering the color balance is calculated.

  Next, the unevenness correction unit 13 calculates the calculated correction amounts 0 (%), 3.6 (%), 3.6 (%) for the gradation values R ′, G ′, and B ′ for each color component before correction. ) To correct. Specifically, the gradation values R ′, G ′, and B ′ are respectively corrected by the numerical values (100%, 96.4%, and 96.4%) that are increased or decreased from 100 (%) by the correction amount. .

  In this way, by using the luminance measurement value for each color component (see FIG. 4) with respect to the gradation value unique to the display unit 15, luminance unevenness and color unevenness are corrected while maintaining the color balance of the input image signal. Is possible. Rather than using a different correction coefficient for each color component or using a correction amount obtained in advance for a specific input gradation value, the correction amount is calculated each time using luminance information based on actual measurement. Accordingly, it is possible to avoid the occurrence of uneven color and uneven brightness.

(Embodiment 2)
In the first embodiment, the conversion unit 12, the unevenness correction unit 13, and the like are each configured to be realized by each module configuring the ASIC because high-speed processing is required. However, the present invention corrects color unevenness and luminance unevenness of an image displayed on a monitor connected to the computer device by causing the computer device to execute a computer program for executing the correction method according to the present invention. But you can. FIG. 8 is a block diagram showing a configuration when the correction method according to the present invention is implemented by a computer apparatus. In this case, the computer apparatus 3 includes a control unit 30 such as a CPU and an MPU, a storage unit 31 such as a hard disk (Hard Disk), an EEPROM (Electronically Erasable and Programmable Read Only Memory), and the corrected image signal to the monitor 4. And an output unit 32 for outputting.

  The storage unit 31 stores a control program 3P for causing the correction method according to the present invention to be performed on the image signal generated by the control unit 30. The control program 3P includes a conversion unit 33 and an unevenness correction unit 34, which are modules for causing the control unit 30 to function as the conversion unit 12 and the unevenness correction unit 13 in the display device 1 described above. The control program 3P stored in the storage unit 31 is recorded on a portable recording medium such as a DVD or CD-ROM (not shown), and the control unit 30 includes an auxiliary storage unit (not shown) such as a DVD / CD drive. ), The control program 3P recorded on the portable recording medium may be stored in the storage unit 31.

  The storage unit 31 stores a correction table 35 corresponding to the LUT 16 and the register 17 in the first embodiment. The correction table 35 includes a non-uniformity amount 36, a correction coefficient 37, and luminance measurement value information 38.

  The control unit 30 of the computer device 3 having such a configuration reads and executes the control program 3P from the storage unit 31, and the image signal generated by the control unit 30 is received by the function of the unevenness correction unit 34 included in the control program 3P. The gradation value of each color component to be expressed is corrected by a correction amount or correction coefficient adjusted according to the maximum gradation value of each color component corresponding to various color balance settings, and appropriate luminance unevenness is determined according to the color balance setting. Color unevenness correction can be performed. A communication interface may be further provided between the computer device 3 and the monitor 4, and the conversion unit 12 and the unevenness correction unit 13 in the monitor 4 having the same configuration as the display device 1 may be controlled from the control program 3P.

  In Embodiments 1 and 2, the luminance measurement value information stored in the LUT 16 or the storage unit 31 has been described as a ratio obtained by dividing the center luminance for each color component by the luminance in each region. However, the present invention is not limited to this, and conversely, a value divided by the center luminance may be used, or a luminance measurement value for each color component may be simply stored as it is.

  In the first and second embodiments described above, the correction for the gradation values of a plurality of color components is given as an example, but the present invention may be applied to the correction for the gradation values in a monochrome image signal.

(Embodiment 3)
The display device according to the third embodiment is obtained by adding a function of performing appropriate unevenness correction to a change in brightness (brightness) setting to the display device 1 according to the above-described first embodiment. FIG. 9 is a schematic diagram for explaining a change in luminance unevenness with respect to a change in brightness setting. In the illustrated example, when the brightness of the display device can be set arbitrarily or stepwise in the range of 0% to 100%, the brightness of the display image in three settings of brightness 0%, 50%, and 100% It shows unevenness. As illustrated, the luminance unevenness of the display image changes according to the brightness setting. For this reason, in the unevenness correction process optimized for one of the brightness settings, the effect of unevenness correction may be reduced in other brightness settings, and it is desirable to perform unevenness correction corresponding to changes in the brightness setting. It is.

  The display device 1 according to the third embodiment receives the change of the brightness setting through the operation unit 18 and notifies the conversion unit 12, the unevenness correction unit 13, and the like. The conversion unit 12 converts the image signal in accordance with the notified brightness setting. The unevenness correction unit 13 performs unevenness correction corresponding to the change in the brightness setting by correcting the brightness measurement value information stored in the LUT 16 in accordance with the notified brightness setting.

  A method for correcting unevenness corresponding to a change in brightness setting will be described below. FIG. 10 is a schematic diagram showing a change in luminance with respect to a change in brightness setting for each area of the display screen. In the illustrated example, the display screen of the display device is divided into 3 × 3 areas (center and areas A to H), and the characteristics of the luminance change in each area are shown as graphs. In each graph, the horizontal axis represents the brightness setting (0% to 100%), and the vertical axis represents the ratio between the luminance of each region and the luminance of the center (center luminance / luminance of each region).

  As shown in the figure, the characteristic of the luminance change with respect to the change of the brightness setting is different for each region. However, as a result of investigating various display devices, the inventor of the present application has found that the luminance change characteristics of the respective regions are substantially the same if the display devices are of the same model. The characteristics in each region can be approximated by a linear function or a quadratic function that monotonously increases or monotonously decreases.

  Therefore, in the unevenness correction of the display device 1 according to the third embodiment, first, the basic characteristics of the luminance change of each region with respect to the brightness setting are determined at the design stage or the trial production stage of the display device 1, and The basic characteristics are stored in the memory of the display device 1 or the like. Here, the basic characteristic is a correspondence relationship between brightness and luminance (ratio of luminance of each region and luminance of the center), and a coefficient is determined as a linear function or a quadratic function that is undetermined. Further, the basic characteristics and the change characteristics described later are individually determined for each color of RGB.

  However, the coefficient undetermined function stored in the display device 1 as the basic characteristic of each area is determined to the extent that the coefficient is determined by giving two pieces of brightness-luminance measurement information. Since the coefficient of the linear function is two, the coefficient can be determined from the measurement information of two points. The coefficient of the quadratic function is three, but it is undecided by adding information such as whether the quadratic function is monotonously increasing or monotonically decreasing and the brightness value (initial value) at 0% brightness. A quadratic function is materialized so that there are two coefficients.

  Next, in the manufacturing process or test process of the display device 1, the brightness-brightness measurement of each region is performed for each display device 1 with two settings of, for example, 50% and 100% brightness, and the basic characteristics are obtained from the obtained measurement results. The coefficient of the function stored as is calculated. This calculation result is stored in the LUT 16 or other memory as a luminance change characteristic with respect to the brightness setting.

  As described in the first embodiment, the display device 1 of the present invention stores luminance measurement information in the LUT 16 and calculates a correction amount for unevenness correction from the luminance measurement information. For this reason, it is necessary to perform luminance measurement in the manufacturing process or test process of the display device 1, and the brightness setting at this time is performed at the factory setting (for example, brightness 50%). In addition to the above luminance measurement, the display device 1 according to the third embodiment performs the same luminance measurement at another brightness setting (for example, brightness 100%), thereby realizing the luminance measurement at two brightness settings. it can. That is, the display device 3 according to the third embodiment needs to perform luminance measurement only once more than the display device 1 according to the first embodiment. Note that the luminance measurement for the correction method described in the first embodiment (luminance measurement at the brightness setting at the time of shipment from the factory) needs to be performed a plurality of times such as RGB gradation values of 255, 192, 128. However, the additional luminance measurement for the correction method according to the third embodiment may be performed only once when the RGB gradation value is 255, for example.

  Thereafter, when the display device 1 is used by the user and the brightness setting is changed by the user, the unevenness correction unit 13 of the display device 1 uses the luminance measurement information stored in the LUT 16 based on the luminance change characteristic with respect to the brightness setting. (Brightness measurement information at 50% brightness) is modified to brightness measurement information according to the changed brightness setting, and primary work such as memory (SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory)) Memory). Note that the luminance measurement information stored in the LUT 16 is not overwritten, and the unevenness correction unit 13 corrects the luminance measurement information stored in the LUT 16 every time the brightness setting is changed.

  After the correction of the luminance measurement information is completed, the unevenness correction unit 13 of the display device 1 uses the corrected luminance measurement information stored in the memory instead of the luminance measurement information stored in the LUT 16 in the first embodiment. The described unevenness correction processing is performed. The unevenness correction unit 13 performs unevenness correction processing based on the corrected luminance measurement information, whereby unevenness correction suitable for brightness setting can be performed, and an image display without unevenness can be realized by the display device 1.

  FIG. 11 is a flowchart for explaining a procedure of processing performed before factory shipment of the display device 1 for unevenness correction according to the third embodiment. First, in the design stage or trial manufacture stage of the display device 1, for each region obtained by dividing the display screen into a predetermined size, the basic characteristics of the change in luminance with respect to the change in brightness setting are determined (step S21). The expressed basic characteristics are stored in the memory of the display device 1 (step S22).

  Next, in a manufacturing process or a test process of the display device 1, luminance measurement is performed with a brightness of 50% (step S23), and further luminance measurement is performed with a brightness of 100% (step S24). Based on these measurement results, the coefficient of the basic characteristic stored in step S22 is calculated to calculate the luminance change characteristic with respect to the brightness setting (step S25), and the calculated change characteristic is stored in the memory of the display device 1. Store (step S26), and the process ends.

  FIG. 12 is a flowchart illustrating a processing procedure performed when the display device 1 according to the third embodiment changes the brightness setting, and is a processing procedure performed by the unevenness correction unit 13 of the display device 1. The unevenness correction unit 13 determines whether or not the brightness setting has been changed by determining the presence / absence of a notification from the operation unit 18 (step S31). If the brightness setting has not been changed (S31). : NO), and waits until the brightness setting is changed.

  When the brightness setting is changed (S31: YES), the unevenness correction unit 13 reads the luminance measurement information from the LUT 16 (step S32), and reads the change characteristics stored in advance in step S26 described above (step S33). ). Next, the unevenness correction unit 13 corrects the luminance measurement information based on the changed brightness setting and the read change characteristic (step S34), stores the corrected luminance measurement information in the memory (step S35), and The process ends.

  The display device 1 according to the third embodiment having the above configuration is configured to correct the brightness measurement information stored in the LUT 16 for use in the unevenness correction process in accordance with the brightness setting, thereby preventing the brightness setting from being changed. However, appropriate unevenness correction can be performed, and image display without unevenness can be performed with respect to various brightness settings.

  In addition, the basic characteristic of the change in brightness with respect to the brightness setting is determined in advance for each area of the display screen, and the change characteristic of each area is calculated and stored based on the measurement result and the basic characteristic of the luminance measurement in the two brightness settings. In addition, when the brightness setting is changed, the luminance measurement information stored in advance in the LUT 16 is corrected based on the change characteristic, whereby the luminance measurement information according to the brightness setting can be obtained. Unevenness correction suitable for setting can be performed.

  Further, the change characteristic is calculated by calculating the coefficient of the basic characteristic based on the result of the luminance measurement, with the basic characteristic obtained by approximating the luminance change with respect to the brightness setting by a linear function or a quadratic function whose coefficient is undetermined. By adopting the configuration, the change characteristic can be calculated based on the luminance measurement results at two settings such as brightness 50% and 100%, and an increase in measurement time in the manufacturing process or the test process can be suppressed. Further, by including the maximum brightness (100%) in the brightness setting when performing luminance measurement, it is possible to obtain a luminance change characteristic with high accuracy with respect to a change in brightness setting.

  In the present embodiment, an example in which the display screen is divided into 3 × 3 9 regions is shown in FIG. 10, but the present invention is not limited to this, and the actual luminance measurement information correction processing is shown in FIG. The display screen is divided into more areas as shown in FIG. In addition, brightness measurement is performed with two settings of brightness 50% and 100%. However, the present invention is not limited to this, and it is also possible to calculate change characteristics by performing brightness measurement with three or more brightness settings. Good. The correction method performed in the present embodiment may be configured to be performed by a computer program such as the control program 3P as shown in the second embodiment.

(Embodiment 4)
The display device according to Embodiment 4 is obtained by adding a function of adjusting the degree of unevenness correction to the display device according to Embodiment 3 described above. FIG. 13 is a schematic diagram for explaining the relationship between the degree of unevenness correction, the maximum luminance, and the contrast ratio. The unevenness correction is a process of correcting a high luminance area to a low luminance area when the input video level is maximum. Therefore, as shown in the figure, the stronger the unevenness correction, the lower the maximum luminance (and contrast ratio) of the display screen. Whether priority should be given to the degree of unevenness correction or the maintenance of the maximum brightness (and contrast ratio) varies depending on the type of image to be displayed and the mode of use of the display device, etc., but when the brightness is set high It is presumed that the user is demanding display with high luminance and high contrast, and when the brightness is set low, it is presumed that display with high luminance and high contrast is not demanded.

  Therefore, the display device 1 according to the fourth embodiment adjusts the degree of unevenness correction according to the brightness setting by the user. The degree of unevenness correction can be adjusted by increasing or decreasing the amount of unevenness shown in FIG.

  The display device 1 according to the fourth embodiment stores a plurality of unevenness amounts according to the brightness setting in the LUT 16. For example, in the LUT 16, the amount of unevenness used at a setting of brightness 0% to 30%, the amount of unevenness used at a setting of brightness 31% to 65%, and the unevenness used at a setting of brightness 66% to 100%. The unevenness correction unit 13 reads out any unevenness amount according to the brightness setting and performs unevenness correction.

  The amount of unevenness used when the brightness is set to 0% to 30% is an amount of unevenness for strongly performing unevenness correction. The amount of unevenness used with the brightness of 31% to 65% is an amount of unevenness for performing unevenness correction at a moderate level. Further, the amount of unevenness used at a setting of brightness 66% to 100% is an amount of unevenness for performing unevenness correction weakly.

  FIG. 14 is a flowchart showing a procedure of processing performed when the display device 1 according to Embodiment 4 changes the brightness setting, and is a procedure of processing performed by the unevenness correction unit 13 of the display device 1. In FIG. 14, illustration of the luminance measurement information correction process (see FIG. 12) accompanying the change of the brightness setting is omitted.

  The unevenness correction unit 13 determines whether or not the brightness setting has been changed by determining whether or not there is a notification from the operation unit 18 (step S41). If the brightness setting has not been changed (S41). : NO), and waits until the brightness setting is changed.

  When the brightness setting is changed (S41: YES), the unevenness correction unit 13 determines whether the brightness setting is 0% to 30% (step S42), and the brightness setting is not 0% to 30%. In this case (S42: NO), it is further determined whether or not the brightness setting is 31% to 65% (step S43).

  When the brightness setting is 0% to 30% (S42: YES), the unevenness correction unit 13 reads the unevenness amount for strongly performing unevenness correction from the LUT 16 (step 44), and ends the process. When the brightness setting is 31% to 65% (S43: YES), the unevenness correction unit 13 reads the unevenness amount for performing unevenness correction with a moderate degree from the LUT 16 (step 45), and ends the process. When the brightness setting is not 31% to 65% (S43: NO), that is, when the brightness setting is 66% to 100%, the unevenness correction unit 13 reads out the unevenness amount for weakly correcting unevenness from the LUT 16. (Step 46), the process ends. The amount of unevenness read in steps S44 to S46 is used in subsequent unevenness correction processing.

  The display device 1 according to the fourth embodiment having the above-described configuration adjusts the degree of unevenness correction according to the brightness setting, so that the degree of unevenness correction and the maximum luminance in a trade-off relationship are displayed by the user. It is possible to adjust the setting suitable for the usage mode 1. Further, by storing a plurality of unevenness amounts according to the brightness setting in the LUT 16 and reading out the unevenness amounts according to the brightness setting from the LUT 16 when the brightness setting is changed, the unevenness according to the brightness setting is read. Adjustment of the degree of correction can be easily realized.

  In the present embodiment, the unevenness amount is switched with three settings of brightness 0% to 30%, 31% to 65%, and 66% to 100%. However, this is only an example. It is not limited. Particularly, the numerical value of the brightness setting related to the switching of the unevenness amount is an example. Further, for example, the unevenness amount may be switched by setting two types or four or more types. The correction method performed in the present embodiment may be configured to be performed by a computer program such as the control program 3P as shown in the second embodiment.

  The disclosed embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Display apparatus 12 Conversion part 13 Unevenness correction part 16 LUT
17 register 30 control unit 3P control program 33 conversion unit 34 unevenness correction unit

Claims (12)

When displaying an image composed of a plurality of pixels on the display screen, the intensity for each color component corresponding to each pixel of the image is determined according to the corresponding position in the display screen where the pixel is displayed and the intensity. In the correction method to correct,
For each of a plurality of areas constituting the display screen, measure the luminance when displaying a single intensity image on the display screen,
First luminance information for each color component and each region based on the measured luminance, second luminance information for each region based on the measured luminance, and a correction coefficient corresponding to each of a plurality of intensities are stored.
When displaying an image on the display screen, the first luminance information for each color component of the region corresponding to the position of the pixel on the display screen, the second luminance information of the region, and the color of each pixel of the image Read the correction coefficient corresponding to the maximum intensity of the component,
A correction method, wherein the intensity of each color component of each pixel of the image is corrected based on the read first luminance information, second luminance information, and correction coefficient. When displaying an image composed of a plurality of pixels on the display screen, the intensity for each color component corresponding to each pixel of the image is determined according to the corresponding position in the display screen where the pixel is displayed and the intensity. In the correction method to correct,
When displaying an image on the display screen, first brightness information for each of a plurality of areas and color components constituting the display screen stored in advance, and a second brightness for each of the plurality of areas constituting the display screen Read out correction information corresponding to each of information and multiple intensities,
The intensity for each color component of each pixel of the image includes the first luminance information for each color component in the area corresponding to the position of the pixel on the display screen, the second luminance information for the area, and the maximum intensity of the color component. A correction method characterized by correcting based on a correction coefficient corresponding to. Wherein the first luminance information, the luminance measurement at a particular position in the display screen, according to claim 1 or claim, characterized in that the ratio of each color component of the luminance measurement in the plurality of areas respectively 2. The correction method according to 2 . The second luminance information is a ratio of the luminance in each of the plurality of regions to the luminance in the specific region when displaying an image whose intensity for each color component is a specific value.
When displaying an image on the display screen, the correction coefficient corresponding to the intensity of each color component corresponding to each pixel of the image, and the second luminance information of the region corresponding to the position of the pixel,
Multiplying the addition result by the first luminance information corresponding to the intensity of each color component;
Subtract the multiplication result from any reference value,
The correction method according to claim 3 , wherein the correction is performed by multiplying a value based on a subtraction result by an intensity for each color component. The brightness when displaying an image on the display screen can be changed,
In accordance with the brightness at the time of display, the stored first luminance information is corrected,
The intensity of each color component of each pixel of the image, first luminance information and correct any one of claims 1 to 4, characterized in that the correction based on the second luminance information and the correction factor Correction method described in 1. For each of the areas, a basic characteristic of a change in luminance with respect to brightness is determined in advance,
For each area, measure the luminance when displaying an image of a predetermined intensity on the display screen at at least two brightnesses,
In accordance with the measured brightness and the basic characteristics, for each region, calculate the change characteristics of the brightness with respect to the brightness,
Store the calculated change characteristics,
The correction method according to claim 5 , wherein when the first luminance information is corrected, the first luminance information is corrected based on brightness at the time of display and a stored change characteristic. The basic characteristics are characteristics approximated by a linear function or a quadratic function whose coefficients are undetermined,
The correction method according to claim 6 , wherein the calculation of the change characteristic is performed by calculating a coefficient of the linear function or a quadratic function according to luminance measured at least at two brightness levels. Wherein at least two brightness correction method according to claim 6 or claim 7, characterized in that it comprises a maximum brightness. When displaying an image composed of a plurality of pixels on the display screen, the intensity for each color component corresponding to each pixel of the image corresponds to the display screen on which the pixel is displayed. In a display device comprising a correction means for correcting according to the position and the intensity,
Corresponding to each of the first luminance information for each color component and each region based on the measured luminance value for each of the plurality of regions constituting the display screen, the second luminance information for each region based on the measured luminance value, and the plurality of intensities. A storage unit in which correction coefficients to be stored are stored;
The first luminance information for each color component of the region corresponding to the position of each pixel of the image to be displayed, the second luminance information of the region, and the correction coefficient corresponding to the maximum intensity of the color component of each pixel Means for reading from the storage unit,
The display device, wherein the correction unit corrects the intensity of each color component in each pixel based on the read first luminance information, second luminance information, and correction coefficient. The brightness when displaying an image on the display screen can be changed,
The storage unit stores a luminance change characteristic with respect to brightness,
Correction means for correcting the read first luminance information based on brightness at the time of display and stored change characteristics;
The correction means corrects the intensity of each color component in each pixel based on the first luminance information corrected by the correction means, the second luminance information, and the correction coefficient. The display device according to claim 9 . A specific area when an image having a single intensity is displayed on the display screen for each of a plurality of areas constituting the display screen of the image display means on a computer having means for outputting an image signal to the image display means The first ratio for each color component between the measured luminance value and the measured luminance value in each of the plurality of regions, and the plurality of the luminance values for the specific region when an image having a specific value for each color component is displayed. A computer program for correcting the intensity of a color component corresponding to each pixel included in an image signal, using a second ratio of luminance in each region and a correction coefficient corresponding to each of a plurality of intensities,
On the computer,
For the intensity of each color component corresponding to each pixel of the image represented by the output image signal, the correction coefficient corresponding to the maximum intensity of the color component and the second ratio of the area corresponding to the position of the pixel The step of adding,
Multiplying the addition result by the first ratio corresponding to the intensity of each color component;
Subtracting the multiplication result from an arbitrary reference value; and
A computer program for executing the step of multiplying the intensity for each color component corresponding to each pixel of an image represented by an output image signal by a subtraction result. Further using a luminance change characteristic with respect to brightness when displaying an image on the display screen,
The computer program according to claim 11 , causing the computer to execute a step of correcting the first ratio based on brightness and the change characteristic.