JP4542988B2 - Correction method and display device - Google Patents

Description

  The present invention relates to the brightness of a display image displayed on a display screen of a display device based on an image signal indicating gradation values of a plurality of color components, for each screen region obtained by dividing the display screen into a plurality of regions. In particular, the present invention relates to a correction method for correcting to a target luminance based on the measurement results and a display device to which the correction method is applied, and more particularly to a correction method and a display device for correcting color unevenness in a display image.

  LCD (Liquid Crystal Display) monitor, EL (Electro Luminescence) monitor, PDP (Plasma Display Panel) monitor, display screens of display devices such as projectors cause unevenness in brightness, color unevenness, etc. due to variations in manufacturing quality. There is a problem that it ends up. For example, in the case of a liquid crystal panel that is a display unit of an LCD monitor, variations in the thickness of the liquid crystal layer, variations in operating characteristics of the driving transistor, and variations in the light emission distribution of the backlight can be exemplified as causes of display unevenness.

  A method for correcting display unevenness of a conventional display device will be described. First, a method for correcting luminance unevenness of the display device will be described. In order to correct the luminance unevenness of the display device, first, the luminance unevenness of the display device is measured. The measurement of luminance unevenness is performed by displaying a white image based on a specific gradation value on the entire display screen of the display device and measuring the luminance of the displayed image with the measurement device.

  FIG. 15 is a chart showing the results of measuring the luminance of the display screen of the display device. In FIG. 15, the luminance is measured for each screen area obtained by dividing the display screen into a plurality of areas, and the values obtained by the measurement are shown for each screen area. As shown in FIG. 15, even when an image based on the same gradation value is displayed on the entire screen, the brightness varies from screen area to screen area. In general, the brightness at the center of the screen is the highest and the brightness at the periphery is higher. Tend to be lower. Therefore, in order to correct such luminance unevenness, the luminance is corrected for each screen area. The correction of luminance is usually performed in a direction of decreasing the luminance. This is to avoid saturation at high luminance when correction is performed by increasing the luminance.

FIG. 16 is a chart showing the target brightness of each screen area of the display device. FIG. 16 shows a target luminance that is a target of luminance correction that is set based on the luminance shown in FIG. Normally, the screen area is finely divided as illustrated in FIG. 12, but FIGS. 15 and 16 illustrate a simplified chart divided into 3 × 3 for ease of explanation. As shown in FIG. 16, the target luminance is not necessarily set to a constant value in each screen area. If the target brightness is set to the brightness of the screen area having the lowest measured value, for example, 136 cd / m ² or less in the example of FIG. 15, the brightness can be made uniform in the entire screen area. However, when the target luminance is set to the luminance of the screen area having the lowest measured value, the luminance is excessively reduced. Therefore, it is general that the target luminance is set to a luminance that can be lowered, and the luminance is not corrected for a screen area less than the target luminance.

In the example shown in FIG. 16, the target brightness of each screen area when the target brightness is set to 90% of the brightness of the central screen area, that is, 157 cd / m ² × 0.9 = 141 cd / m ² is shown. For screen areas where the measured brightness is equal to or greater than the target brightness, brightness uniformity is achieved, but for screen areas less than the target brightness indicated by the diagonal lines in FIG. 16, brightness uniformity is not achieved. . However, although it is not possible to eliminate luminance unevenness for the entire screen area, it does not cause an excessive decrease in luminance. Therefore, the target luminance is generally set in this way. Then, a luminance image obtained by performing correction based on the target luminance set for each screen area with respect to the gradation value input as the image signal is displayed on the display screen of the display device.

  Next, a method for correcting color unevenness of the display device will be described. In the correction of color unevenness, the brightness unevenness correction performed based on the white image is performed on the brightness unevenness of each color component constituting the image. In order to correct the color unevenness of the display device, first, the color unevenness of the display device is measured. While the measurement of luminance unevenness is performed by displaying a white image, the measurement of color unevenness is performed by specifying a single color component, that is, an R (Red) component, a G (Green) component, and a B (Blue) component. This is done by displaying a monochrome image based on the gradation value of the image on the entire display screen of the display device and measuring the luminance of the displayed monochrome image with the measuring device.

  FIG. 17 is a chart showing values obtained by measuring the luminance of the display screen of the display device. FIG. 17 shows measurement values of luminance for each screen area. FIG. 17A shows a measurement value based on an R component monochrome image, FIG. 17B shows a measurement value based on a G component monochrome image, and FIG. Reference numeral 17 (c) shows a measurement value based on a monochrome image of the B component. As for the color unevenness, the correction in the direction of decreasing the brightness is performed in the same manner as the brightness unevenness.

  FIG. 18 is a chart showing the target brightness of each screen area of the display device. FIG. 18 shows target brightness that is a target of brightness correction that is set based on the brightness shown in FIG. 17. FIG. 18A shows the target brightness of the R component, and FIG. FIG. 18C shows the target luminance of the B component. The setting of the target luminance is the same as the luminance unevenness. For each color component, the value 90% of the luminance of the central screen region is set as the target luminance of each color component, and the screen region less than the target luminance shown by the oblique lines in FIG. For, the measured value is set as the target luminance. Then, a luminance image obtained by correcting the gradation value of each color component input as an image signal based on the target luminance for each color component set for each screen area is displayed on the display screen of the display device.

In addition to the apparatus as described above, an apparatus for correcting color unevenness is disclosed in Patent Document 1, for example.
Japanese Patent Laid-Open No. 2001-343554

  However, the conventional correction method completely eliminates color unevenness because there is a difference in the RGB ratio between the screen area where the color component has been corrected to achieve the target brightness and the area where correction has not been performed. There is no problem. For example, in the example shown in FIG. 18, in the screen area that has been corrected based on the target luminance, the luminance RGB ratio is 48.5: 81.6: 12.1, whereas the screen area that has not been corrected. For example, in the upper left screen area, the RGB ratio of luminance is 44.5: 81.2: 11.8. Note that if the target brightness is set to the brightness of the screen area with the lowest measured value and correction is performed for all screen areas, the color unevenness is eliminated, but in that case, the brightness of the entire screen is reduced. There's a problem.

  The present invention has been made in view of such circumstances, and a ratio based on the color component ratio of the target luminance with respect to a screen area that is not corrected to the target luminance set for each color component based on the measurement result for each color component. An object of the present invention is to provide a correction method capable of eliminating color unevenness without causing unnecessary luminance reduction by correcting color components, and a display device to which the correction method is applied.

The correction method according to the first aspect of the present invention relates to the brightness of the display image displayed on the display screen of the display device based on the image signal indicating the gradation values of the plurality of color components, for each screen region obtained by dividing the display screen into a plurality of regions. In addition, in the correction method for correcting to the target luminance based on the result measured by the measuring device, the luminance of the display image displayed on the display screen of the display device based on the gradation value of one color component indicated by the image signal Is measured for each color component, and the first target luminance for each color component is set to a value that allows the luminance to be reduced with reference to the measurement result of the luminance for each color component in each screen region . all screen area measurement result is first target brightness or respectively, were determined on the first screen region to be corrected to the first target brightness set to calculate a ratio of each color component of the first target brightness, the first All screen areas other than the screen area And area, the second screen region of each and less than the first target brightness, respectively set the luminance and the same color component ratio and the color component ratio of the first target brightness calculated as the second target brightness, the The present invention is characterized in that the luminance of one screen area is corrected to a first target luminance, and each luminance of each second screen area is corrected to a respective second target luminance.

The correction method according to the second aspect of the present invention provides a display image brightness displayed on a display screen of a display device based on an image signal indicating gradation values of a plurality of color components for each screen region obtained by dividing the display screen into a plurality of regions. In addition, in the correction method for correcting to the target luminance based on the result measured by the measuring device, the measuring device is displayed on the display screen of the display device based on the gradation value of one color component indicated by the image signal. the brightness of the display image that was respectively determined for each color component, the display device, the measurement result of the luminance of each color component of each screen area referenced to the allowable decrease of the luminance of the first target brightness of each color component All the screen areas in which the measurement results of all the color components are equal to or higher than the first target brightness are set as the first screen areas, and the brightness of the first screen area is set to the first for each set color component. Corrected to the target brightness, and after the first screen area As the second screen area, each second screen area is less than the first target brightness and is set to the same color component ratio as the color component ratio of the first target brightness. The second target luminance is corrected.

  A correction method according to a third invention is the correction method according to the first or second invention, wherein the second target luminance is selected based on a difference between a color component ratio of a measurement result of each color component and a color component ratio of the first target luminance. It is set based on the measured result of the one color component.

  The correction method according to a fourth invention is the correction method according to any one of the first to third inventions, wherein the luminance correction for each color component is performed after the luminance of each screen region is corrected based on the measurement result of the achromatic display image. It is characterized by that.

In the display device according to the fifth aspect of the invention, the brightness of the display image displayed on the display screen is set for each screen area obtained by dividing the display screen into a plurality of areas based on image signals indicating gradation values of a plurality of color components. In the display device that corrects the target luminance for each color component , all the luminances of all the color components of the display image are equal to or higher than the first target luminance that is set in advance for each color component to a value that allows a reduction in luminance. Each screen area is a first screen area, the brightness of the first screen area is corrected to a first target brightness, and all screen areas other than the first screen area are second screen areas. The region is characterized by comprising means for correcting to a second target luminance for each color component that is less than the first target luminance and set to the same color component ratio as that of the first target luminance.

  In the present invention, the luminance of the second screen area is corrected to the second target luminance set for each color component at a ratio based on the color component ratio of the first target luminance, for example, the luminance is lower than the first target luminance. Therefore, since the color component ratio of the second screen area that is not corrected to the first target luminance is the same as the color component ratio of the first screen area, the color component ratio of the entire screen is constant, so that color unevenness is eliminated. In addition, since it is not necessary to adjust the luminance of the entire screen to the luminance of the screen region having the lowest luminance, it is possible to prevent the luminance of the entire screen from being lowered.

  In the present invention, the color component that is the reference for setting the second target luminance is selected on the basis of the measurement result of each color component and the difference between the first target luminance, so that each screen region is selected according to the display characteristics of each color component. It is possible to perform an optimal correction for the above.

  Furthermore, in the present invention, it is possible to realize highly accurate correction of display unevenness including brightness unevenness and color unevenness by using together with correction of brightness unevenness.

  In the correction method and the display device according to the present invention, the brightness of the display image displayed based on the gradation value of one color component indicated by the image signal is determined for each screen area obtained by dividing the display screen into a plurality of areas. Each color component is measured, a first target luminance for each color component is set based on the measurement result for each color component, and a first screen area that is corrected to the set first target luminance is set to the measurement result and the first target luminance. The ratio is determined based on the relationship, the ratio of each color component of the first target luminance is calculated, and the color at a ratio based on the calculated color component ratio of the first target luminance for each of the second screen areas other than the first screen area A second target brightness for each component is set, the brightness of the first screen area is corrected to the first target brightness, and the brightness of each second screen area is corrected to the respective second target brightness.

  With this configuration, in the present invention, for example, the color component ratio of the second screen area that is not corrected to the first target brightness because the brightness is lower than the first target brightness is the same as the color component ratio of the first screen area. Since the color component ratio of the entire screen is constant, there are excellent effects such as elimination of color unevenness. In addition, since it is not necessary to adjust the brightness of the entire screen to the brightness of the screen area having the lowest brightness, it is possible to prevent the brightness of the entire screen from being lowered, and thus excellent effects can be obtained.

  In the present invention, the second target brightness is set based on the measurement result of one color component selected based on the difference between the measurement result of each color component and the first target brightness, so that the display characteristics of each color component are obtained. Accordingly, it is possible to perform an optimum correction for each screen area, and thus an excellent effect can be obtained.

  Furthermore, in the present invention, after correcting the luminance unevenness for correcting the luminance of each screen area based on the measurement result of the achromatic display image such as white, the display unevenness including the luminance unevenness and the color unevenness is corrected by correcting the color unevenness. It is possible to realize a highly accurate correction of the above, and so on.

  Hereinafter, the screen showing the embodiment of the present invention will be described in detail.

  FIG. 1 is a perspective view showing an example of the appearance of the display device of the present invention. In FIG. 1, reference numeral 1 denotes a display device such as an LCD monitor. The display device 1 is connected to a processing device 2 such as a personal computer, and receives an input of an image signal output from the processing device 2 and receives the received image. A display image of the luminance value based on the tone value of the signal is displayed on the display screen of the display unit 10 such as a liquid crystal panel. The image signal output from the processing device 2 to the display device 1 includes gradation values for a plurality of color components, that is, an R (Red) component, a G component (Green) component, and a B (Blue) component. . The display device 1 is not limited to an LCD monitor, and may be a device such as an EL monitor, a PDP monitor, or a projector. The processing device 2 is not limited to a personal computer, but may be a TV tuner, a DVD player, or a game. A device such as a machine may be used.

  FIG. 2 is a perspective view conceptually showing a measurement example of display unevenness in the correction method of the present invention. The display unevenness of the display device 1 is measured by displaying an image based on the image signal having the same gradation value on the entire display screen of the display unit 10 and measuring the brightness of the display screen using the measuring device 3. An image to be displayed based on an image signal having the same gradation value as a luminance measurement target is a single color image of each color component, that is, a single color image of each of the R component, G component, and B component, and an achromatic color such as a white image. It is an image. Thereby, the relationship between the gradation value and the luminance of the image displayed on the entire display screen can be obtained, and the distribution of the luminance of the entire display screen with respect to the gradation value, that is, the display unevenness can be obtained.

  In the correction method of the present invention, the luminance of the entire display screen is equal to the display unevenness obtained by measuring the luminance of the image displayed on the display unit 10 of the display device 1 with the measuring device 3 as illustrated in FIG. This is done by eliminating luminance unevenness and color unevenness. In order to make the brightness of the entire display screen uniform, the display device 1 sets a target brightness that is a target of brightness correction for each screen area obtained by dividing the display screen of the display unit 10 into a plurality of screen areas. The tone value of the received image signal is corrected so that the luminance becomes the target luminance.

  Next, a display unevenness correction method based on the measurement result will be described. First, a method for correcting luminance unevenness as display unevenness will be described. FIG. 3 is a chart showing the results of measuring the luminance of the display screen of the display device 1 of the present invention. In FIG. 3, the luminance is measured for each screen area obtained by dividing the display screen of the display unit 10 into a plurality of areas, and the luminance value as the measurement result is shown for each screen area. Although FIG. 3 shows a mode in which the screen of the display unit 10 is divided into nine screen regions, the present invention is not limited to this, and the screen may be divided into a number other than 9, for example, a large number of screen regions of 10 or more. It is possible to further classify the pixels. As the number of screen areas to be divided increases, higher-precision luminance unevenness correction becomes possible.

FIG. 4 is a chart showing the target luminance of each screen area of the display device 1 of the present invention. FIG. 4 shows a target luminance that is a target of luminance correction that is set based on the luminance shown in FIG. In the display device 1 of the present invention, the central screen region is set as the reference screen region, and the luminance of 90% of the luminance of the reference screen region is set as the target luminance. However, for the screen area where the measured luminance is less than the target luminance, the measurement result is the target luminance. That is, luminance correction is not performed for a screen area whose measured luminance is equal to or lower than the target luminance. In the example shown in FIG. 4, 90% of the luminance of the central screen area, that is, 157 cd / m ² × 0.9 = 141 cd / m ² is the target luminance. However, since the measured luminance of the screen area indicated by the oblique lines in FIG. 4 is less than 141 cd / m ² , the measurement result becomes the target luminance. In this way, the target luminance for each screen area is set for each gradation value of the image signal. It is not always necessary to set the target luminance for each screen area for all the gradation values. For example, the target luminance for every 32 gradation values is set such that the gradation values are 0, 32, 64,. Similarly, for a gradation value that has not been set, a target brightness that is set by weighted averaging of the target brightness for other gradation values may be calculated.

  Next, a method for correcting color unevenness as display unevenness will be described. FIG. 5 is a chart showing values obtained by measuring the luminance of the display device 1 of the present invention. FIG. 5 shows measured values of luminance for each screen area. FIG. 5A shows measured values based on the R component monochrome image, FIG. 5B shows measured values based on the G component monochrome image, and FIG. 5 (c) shows the measurement value based on the monochrome image of the B component. In FIG. 5, monochromatic images of R component, G component, and B component are displayed on the display unit 10, the luminance is measured for each screen region, and the luminance value as the measurement result is shown for each screen region.

  FIG. 6 is a chart showing the target brightness of each screen area of the display device 1 of the present invention. FIG. 6 shows target brightness correction brightness set based on the brightness shown in FIG. 5, FIG. 6A shows the target brightness of the R component, and FIG. 6B shows the target brightness of the G component. FIG. 6C shows the target luminance of the B component. In the display device 1 of the present invention, with respect to the luminance of each color component, the central screen region is set as the reference screen region, and the luminance of 90% of the luminance of the reference screen region is set as the first target luminance of each color component. However, for the screen area indicated by the oblique lines where the measured brightness is less than the first target brightness, the second target brightness calculated by the method described below is set for each screen area. When necessary in the following description, a screen area in which the first target luminance is set is expressed as a first screen area, and a screen area in which the second target luminance is set is expressed as a second screen area. In addition, when a color component whose measured value is equal to or higher than the first target luminance and a color component lower than the first target luminance are mixed like the screen region in the upper center of FIG. 5, the screen region is defined as the second screen region. deal with.

  When setting the second target luminance, first, the ratio of the R component, G component, and B component of the first target luminance is calculated. In the example of FIG. 6, the ratio of the first target luminance of the R component, G component, and B component is 48.5: 81.6: 12.1.

  Then, for each screen area where the first target luminance is not set, the difference between the corresponding R component, G component, and B component luminance measurement results and the first target luminance color component ratio The reference color component is selected based on the above. The color component ratio of the luminance measurement results of the R component, G component, and B component for each screen area is derived from the content ratio of each color component in the white luminance component. Specifically, the content ratio of the R component is calculated by the following formula 1, the content ratio of the G component is calculated by the formula 2, and the content ratio of the B component is calculated by the formula 3.

Content ratio of R component = luminance of R component / (luminance of R component + luminance of G component + luminance of B component)
...... Formula 1
Content ratio of G component = luminance of G component / (luminance of R component + luminance of G component + luminance of B component)
...... Formula 2
B component content ratio = B component luminance / (R component luminance + G component luminance + B component luminance)
...... Formula 3

For example, in the upper left screen area in FIG. 5, the luminance of the R component, the luminance of the G component, and the luminance of the B component are 44.5 cd / m ² , 81.2 cd / m ² and 11.8 cd / m ² , respectively. The content ratio of the R component, the content ratio of the G component, and the content ratio of the B component are calculated as 0.324, 0.590, and 0.086.

  Since the ratio of the first target brightness of the R component, G component, and B component is 48.5: 81.6: 12.1 = 0.341: 0.571: 0.091, each color of the first target brightness The difference calculated by subtracting the content ratio of each color component from the component ratio is 0.017 for the R component, -0.019 for the G component, and 0.005 for the B component. The color component having the largest difference in the minus direction, in this case, the R component is selected as the reference color component. In the charts illustrated in FIGS. 5 and 6, the R component is the reference color component in all the second screen areas, but it goes without saying that the reference color component may be different for each screen area. Note that the measurement result of the luminance of the reference color component is the second target luminance of the color component in the screen area.

Further, for each screen area in which the first target luminance is not set, the reference color is set such that the ratio of the R component, the G component, and the B component is the same as the ratio of the first target luminance with reference to the luminance of the reference color component. The luminance of color components other than the components is calculated. The calculated brightness is set as the second target brightness of the color component in the screen area. For example, in the upper left screen area, the second target brightness of the G component 74.8cd / m ^2, and the second target brightness of the B component becomes 11.1 cd / m ^2. Since the color component having the largest difference in the minus direction is used as the reference color component in this way, correction is always performed in the downward direction, so that the luminance is not saturated.

  FIG. 7 is a chart showing the target luminance ratio of each screen area of the display device 1 of the present invention. FIG. 7 is a chart showing the ratio between the color components of the first target luminance or the second target luminance set for each screen area, with the target luminance of the R component being 1.00, and FIG. FIG. 7B shows the G component, and FIG. 7C shows the B component. As is clear from FIGS. 7A, 7B, and 7C, the luminance ratio of each color component is constant in all screen areas.

  FIG. 8 is a chart showing the target luminance ratio of each screen area of the display device 1. FIG. 8 is a chart shown for comparison with FIG. 7, in which only the first target luminance is set and the second target luminance is not set, and the luminance as the measurement result is shown as the target luminance. The target luminance of the R component is 1.00, FIG. 8A shows the R component, FIG. 8B shows the G component, and FIG. 8C shows the B component target luminance. As shown in FIG. 8, the ratio of the luminance of the screen area where the first target luminance is set is constant, but in the screen area where the first target luminance indicated by diagonal lines is not set, the ratio between the color components is the screen area. Every one is different. As is apparent from a comparison between FIGS. 7 and 8, color unevenness can be eliminated by setting the second target luminance.

  A method for setting the target luminance for correcting the color unevenness described above will be described with reference to a flowchart. FIG. 9 is a flowchart showing a target luminance setting method for color unevenness correction in the correction method of the present invention. In the correction method of the present invention, the luminance of the display image displayed on the display screen of the display device 1 is measured for each color component based on the gradation value of one color component indicated by the image signal (S101). A first target brightness for each color component is set based on the measurement result for each component (S102), and a first screen area to be corrected to the set first target brightness is determined based on the relationship between the measurement result and the first target brightness. Then, the ratio of each color component of the first target luminance is calculated (S104), and the color component ratio of the measurement result of each color component and the first target are calculated for each of the second screen areas other than the first screen area. A reference color component is selected based on the difference from the luminance color component ratio (S105), and a second target for each color component is selected based on the ratio of the calculated first target luminance color component ratio based on the selected reference color component. Set brightness for each second screen area That (S106). In this way, the first target luminance or the second target luminance of each color component for each screen area is set for each gradation value of the image signal. It is not always necessary to set the target brightness for all the gradation values. For example, the target brightness is set for every 32 gradation values such as 0, 32, 64,... For gradation values that have not been set, a target luminance that is set by weighted averaging of target luminance values for other gradation values is calculated.

  FIG. 10 is a block diagram showing a configuration example of the display device 1 of the present invention. The display device 1 includes an input unit 11 that receives an input of an image signal from the processing device 2, an image controller that executes processing such as conversion processing on the image signal received from the input unit 11, and outputs the image signal after the conversion processing The image signal output from the image processor 12 is output from the display unit 10 as a display image. Further, the display device 1 includes a control unit 13 such as an MPU (Micro Processing Unit) that controls the entire device, and an EPROM (Erasable Programmable Read Only Memory) that records information such as programs and data required for the control of the control unit 13. And a recording unit 14. When the image signal received from the input unit 11 is an analog signal, analog / digital conversion is appropriately performed.

  The image processing unit 12 performs image quality adjustment for an image based on the image signal received from the input unit 11, and display unevenness correction for correcting display unevenness for the image signal adjusted by the image quality adjustment unit 121. Part 122.

  The image quality adjustment unit 121 includes a first adjustment circuit (YCORRECT) 1211 that performs luminance correction on an input image signal, a second adjustment circuit (MATRIX) 1212 that performs color temperature adjustment, and a third adjustment circuit that performs gamma correction. GAMMA) 1213. The first adjustment circuit 1211 can read data from a memory 1214 such as an SRAM (Static Random Access Memory) in which data such as a γ table 1214a required for image quality adjustment is recorded, and the third adjustment circuit 1213 can adjust the image quality. It is possible to read data from a memory 1215 such as an SRAM in which data such as the γ table 1215a required for recording is recorded.

  The display unevenness correction unit 122 includes a brightness unevenness correction circuit 1221 that corrects brightness unevenness and a color unevenness correction circuit 1222 that corrects color unevenness. The brightness unevenness correction circuit 1221 can read data from a memory 1223 such as an SRAM in which data such as a brightness unevenness correction table 1223a required for brightness unevenness correction is recorded, and the color unevenness correction circuit 1222 is required for color unevenness correction. Data can be read from a memory 1224 such as an SRAM in which data such as the color unevenness correction table 1224a is recorded. The brightness unevenness correction table 1223a is a table set based on the target brightness for each gradation value shown in FIG. 4, and the brightness output based on the received gradation value is corrected to the target brightness. A correction coefficient for correcting the tone value is recorded for each screen area. The color unevenness correction table 1224a is a table set based on the gradation value and the target luminance for each color component shown in FIG. 6, and the luminance output based on the received gradation value is corrected to the target luminance. A correction coefficient for correcting the gradation value is recorded for each screen area. The correction coefficient recorded in the luminance unevenness correction table 1223a and the color unevenness correction table 1224a is a numerical value derived based on the relationship between the gradation value based on the result of measuring the display image using the measuring device 3 and the measured luminance. It is.

  Next, processing of the display device 1 of the present invention will be described. FIG. 11 is a flowchart showing processing executed in the display device 1 of the present invention. In the display device 1, the input unit 11 receives an input of an image signal (S 201), and a first adjustment circuit 1211, a second adjustment circuit 1212, and a third adjustment circuit included in the image quality adjustment unit 121 with respect to the received image signal. The image quality of the image based on the image signal is adjusted by 1213 (S202).

  The display device 1 determines the gradation value of the pixel included in each screen area indicated by the image signal whose image quality has been adjusted by the luminance unevenness correction circuit 1221 of the display unevenness correction unit 122 (S203). The brightness unevenness correction table 1223a corresponding to the gradation value of the pixel in the screen area is selected for each pixel (S204), and the correction coefficient recorded in the selected brightness unevenness correction table 1223a is extracted for each pixel (S205). In order to set the luminance of the display image to the target luminance, the gradation value of each screen area is corrected with the extracted correction coefficient (S206). The correction in step S206 is performed by multiplying the gradation value by a correction coefficient.

  The brightness unevenness correction method based on the measurement result of the achromatic display image shown in steps S203 to S206 can be applied to various methods as long as it is a correction method based on the measurement result of the display image. . For example, for the received gradation value, the difference between the brightness of the image that is displayed when correction is not performed and the target brightness that is the correction target is calculated as a brightness correction amount. A correction method in which the correction value of the gradation value is calculated by multiplying the set correction coefficient can be applied. In addition, when such a correction method is applied, an implementation such as what kind of arithmetic circuit is used and what kind of data is recorded is appropriately designed according to the specifications of the display device 1. It is possible.

  Then, the display device 1 uses the color unevenness correction circuit 1222 of the display unevenness correction unit 122 to determine the gradation value for each color component of the pixel included in each screen area indicated by the image signal whose luminance unevenness has been corrected (S207). ), The color unevenness correction table 1224a corresponding to the determined gradation value of each pixel in each screen area is selected for each color component (S208), and the correction coefficient recorded in the selected color unevenness correction table 1224a is selected. Extraction is performed for each color component of each pixel (S209), and the gradation value for each color component of each screen region is corrected with the extracted correction coefficient so that the luminance of the display image becomes the target luminance (S210). The correction in step S210 is performed by multiplying the gradation value by a correction coefficient. The target brightness in step S210 is the target brightness shown by the target brightness setting method described with reference to FIG. 9, and is the first target brightness in the first screen area and the second target brightness in the second screen area. It is brightness.

  Then, the display device 1 displays the image whose luminance has been corrected on the display screen of the display unit 10 (S211).

  The method for correcting color unevenness shown in steps S207 to S210 can be applied to various methods as long as it is a correction method for each color component based on the measurement result for each color component of the display image. For example, for the received gradation value, the difference between the brightness of the image that is displayed when correction is not performed and the target brightness that is the correction target is calculated as a brightness correction amount. A correction method in which the correction value of the gradation value is calculated by multiplying the set correction coefficient can be applied. In addition, when such a correction method is applied, an implementation such as what kind of arithmetic circuit is used and what kind of data is recorded is appropriately designed according to the specifications of the display device 1. It is possible. A part of the procedure shown in the target luminance setting method described with reference to FIG. 9, for example, the procedure of steps S102 to S106, may be configured as a process to be executed at this stage.

  The above-described processing is executed by appropriately sharing the processing in cooperation with various hardware and software in the image processing unit 12 of the display device 1 illustrated in FIG. They may be connected and executed in cooperation with the connected processing device 2.

Next, the result of correction by the correction method of the present invention will be described. FIGS. 12, 13 and 14 are explanatory diagrams showing the color unevenness distribution according to the correction method of the present invention. 12, 13, and 14 each show a graph in which the chromaticity of each pixel forming the display screen is arranged in association with the position of the pixel on the display screen. FIG. 12 is a diagram showing the distribution of color unevenness on the display screen only by the x coordinate of the Yxy color system established by the International Commission on Illumination (CIE), and the chromaticity of each pixel forming the display screen. The x-coordinate value in the Yxy color system is the difference from the x-coordinate value of the center pixel, and the distribution of color unevenness on the display screen is represented by a uniform chromaticity difference line connecting pixels having the same difference. Show. FIG. 12A shows the color unevenness distribution before correction, and FIG. 12B shows the color unevenness distribution after correction. FIG. 13 is a diagram showing the distribution of color unevenness on the display screen only by the y coordinate of the Yxy color system, and the value of the y coordinate in the Yxy color system of the chromaticity of each pixel forming the display screen is shown in FIG. The distribution of color unevenness on the display screen is shown by a color difference line connecting pixels having the same difference as the value of the y coordinate of the central pixel. 13A shows the color unevenness distribution before correction, and FIG. 13B shows the color unevenness distribution after correction. FIG. 14 is a diagram showing the distribution of color unevenness on the display screen using the L ^* a ^* b ^* color system, and the color difference expressed by the following equation 4 as the chromaticity of each pixel forming the display screen. ΔE ^* ab is shown with the lightness difference ΔL ^* fixed, and the color unevenness distribution of the display screen is shown by a uniform color difference line connecting pixels having the same color difference ΔE ^* ab. FIG. 14A shows the color unevenness distribution before correction, and FIG. 14B shows the color unevenness distribution after correction.

ΔE ^* ab = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ] ^1/2 Equation 4

  12, 13, and 14 show that the darker the region, the more noticeable the color unevenness. As apparent from FIGS. 12, 13, and 14, the application of the correction method of the present invention eliminates color unevenness over the entire screen area.

  In the above embodiment, after correcting the luminance unevenness, the form for correcting the color unevenness is shown, but the present invention is not limited to this, and can be applied to a form for correcting only the color unevenness. Only a specific screen area, for example, the central screen area is the first screen area, and the other screen areas are the second screen areas.

  In the present invention, luminance unevenness correction may be performed after color unevenness correction, and further, unevenness correction, color unevenness correction, and luminance unevenness correction are repeatedly performed, and display unevenness correction is performed until convergence to a certain value. It is also possible to execute.

  Furthermore, the present invention can be applied not only to RGB but also to a display device provided with pixels to which filters relating to various color components such as W (White) and Y (Yellow) are added.

It is a perspective view which shows an example of the external appearance of the display apparatus of this invention. It is a perspective view which shows notionally the example of a measurement of the display nonuniformity in the correction method of this invention. It is a graph which shows the result of having measured the brightness | luminance of the display screen of the display apparatus of this invention. It is a graph which shows the target brightness | luminance of each screen area | region of the display apparatus of this invention. It is a graph which shows the value which measured the brightness | luminance of the display apparatus of this invention. It is a graph which shows the target brightness | luminance of each screen area | region of the display apparatus of this invention. It is a graph which shows ratio of the target luminance of each screen area | region of the display apparatus of this invention. It is a graph which shows ratio of the target luminance of each screen area | region of a display apparatus. It is a flowchart which shows the setting method of the target luminance for the color nonuniformity correction | amendment in the correction method of this invention. It is a block diagram which shows the structural example of the display apparatus of this invention. It is a flowchart which shows the process performed with the display apparatus of this invention. It is explanatory drawing which shows the color nonuniformity distribution by the correction method of this invention. It is explanatory drawing which shows the color nonuniformity distribution by the correction method of this invention. It is explanatory drawing which shows the color nonuniformity distribution by the correction method of this invention. It is a graph which shows the result of having measured the brightness | luminance of the display screen of a display apparatus. It is a graph which shows the target brightness | luminance of each screen area | region of a display apparatus. It is a graph which shows the value which measured the brightness | luminance of the display screen of a display apparatus. It is a graph which shows the target brightness | luminance of each screen area | region of a display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Processing apparatus 3 Measuring apparatus 10 Display part 11 Input part 12 Image processing part 121 Image quality adjustment part 122 Display unevenness correction part 1221 Luminance unevenness correction circuit 1222 Color unevenness correction circuit

Claims (5)

The result of measuring the luminance of the display image displayed on the display screen of the display device based on the image signal indicating the gradation values of the plurality of color components, by the measuring device for each screen area obtained by dividing the display screen into a plurality of areas. In the correction method for correcting to the target luminance based on
The brightness of the display image displayed on the display screen of the display device based on the gradation value of one color component indicated by the image signal is measured for each color component,
Based on the measurement result of the luminance for each color component in each screen area, the first target luminance for each color component is set to a value that allows the decrease in luminance ,
Determining all screen areas in which the measurement results of all the color components are each equal to or higher than the first target brightness as first screen areas to be corrected to the set first target brightness;
Calculate the ratio of each color component of the first target brightness,
All the screen areas other than the first screen area are set as the second screen areas, and each second screen area is less than the first target luminance and has the same color component ratio as the calculated color component ratio of the first target luminance. Are set as the second target brightness,
A correction method comprising correcting the luminance of the first screen area to a first target luminance and correcting the respective luminances of the second screen areas to respective second target luminances. The result of measuring the luminance of the display image displayed on the display screen of the display device based on the image signal indicating the gradation values of the plurality of color components, by the measuring device for each screen area obtained by dividing the display screen into a plurality of areas. In the correction method for correcting to the target luminance based on
The measuring device is
The brightness of the display image displayed on the display screen of the display device based on the gradation value of one color component indicated by the image signal is measured for each color component,
The display device
Measurement results of the brightness of each color component of each screen area and a reference, the first target brightness of each color component is set to a value acceptable decrease in luminance, the measurement results of all the color components first target brightness respectively All the screen areas as described above are set as the first screen area, the luminance of the first screen area is corrected to the first target luminance for each set color component, and all the screen areas other than the first screen area are corrected to the first screen area. As each of the two screen areas, each second screen area is corrected to a second target brightness for each color component that is less than the first target brightness and set to the same color component ratio as the color component ratio of the first target brightness. A correction method characterized by that.   The second target luminance is set based on a measurement result of one color component selected based on a difference between a color component ratio of a measurement result of each color component and a color component ratio of the first target luminance. The correction method according to claim 1 or 2.   The correction method according to any one of claims 1 to 3, wherein the luminance correction for each color component is performed after the luminance of each screen region is corrected based on a measurement result of an achromatic display image. The brightness of the display image displayed on the display screen based on the image signal indicating the gradation values of multiple color components is corrected to the target brightness for each color component set for each screen area obtained by dividing the display screen into multiple areas. In the display device to
All screen areas in which the brightness of all color components of the display image is equal to or higher than a first target brightness set in advance for each color component to a value that allows a reduction in brightness are defined as the first screen area. The brightness of the area is corrected to the first target brightness, and all the screen areas other than the first screen area are defined as the second screen areas, and each of the second screen areas is less than the first target brightness, A display device comprising: means for correcting the second target luminance for each color component set to the same color component ratio as the color component ratio of the target luminance.

Images