JP6378032B2 - Video processing device, display device, program, recording medium - Google Patents

Description

  The present invention relates to a video processing device, a display device, a program, and a recording medium that perform correction of display unevenness using correction data obtained by calibration processing.

  In recent years, applications such as signage and information displays using large-screen display devices have expanded, and it is possible to display large screens with a single display, or to configure multiple displays by arranging multiple displays in a matrix, An increasing number of systems display on a large screen.

  In the case of a display using a liquid crystal panel, it is configured to include a liquid crystal panel in which a liquid crystal material is sealed between a pair of glass substrates, and a backlight disposed on the back surface of the liquid crystal panel. An image is displayed by driving the liquid crystal panel in accordance with an image signal given from an external device such as a device.

  The liquid crystal display device is equipped with a gate driver and a source driver as a driving circuit for the liquid crystal panel, and the gate driver and the source driver are connected to the gates and sources of the transistors that drive each pixel of the liquid crystal panel and inputted. The on / off of the transistor is controlled based on the image signal, and a voltage (input level to the liquid crystal panel) corresponding to the image signal is applied to the transistor that is turned on, and is determined by the electro-optical characteristics of the liquid crystal substance. The light transmittance is changed. Accordingly, the liquid crystal display device can express gradation by controlling the amount of light emitted from the backlight and transmitted through the liquid crystal panel for each pixel.

  In the liquid crystal panel, the electro-optical characteristics of the liquid crystal material are determined by the distance between the glass substrates in which the liquid crystal material is sealed, that is, the so-called cell gap. Pixels are mixed, the light transmittance of each pixel deviates from the design value, and desired gradation characteristics cannot be obtained, resulting in luminance unevenness and color unevenness. In the liquid crystal display device, luminance unevenness also occurs due to fluctuations in characteristics of a plurality of light sources used for the backlight.

  Therefore, conventionally, in a liquid crystal display device, a calibration process for obtaining a luminance correction table for correcting luminance unevenness from data obtained by photographing a displayed test image, and for correcting chromaticity unevenness Calibration processing for obtaining a chromaticity correction table is performed, and unevenness correction is performed on the video data using these correction tables.

JP2013-97115A JP 2014-26120 A

  When the display device is used as a signage or information display, it is preferable to display with high brightness as much as possible. However, in the brightness unevenness correction, the brightness is corrected so that the brightness of the bright part is close to the brightness of the dark part, so that the brightness of the entire display unit is kept high and brightness unevenness (brightness nonuniformity) is suppressed. Uniform luminance has a trade-off relationship.

  On the other hand, although it depends on the specifications of the display device, the brightness of the dark part (mainly the display screen edge) of the display part when displaying an image with uniform gradation values is the bright part of the display part ( If it is a predetermined ratio or more with respect to the luminance of the portion other than the end portion of the display screen, the luminance is uneven at the end portion of the display screen, but is not so noticeable. Also, if the brightness of the bright part of the display unit is matched with the dark brightness of the screen edge, the entire display unit becomes dark. Accordingly, some display devices for signage and information displays are set to perform color unevenness correction without matching the brightness of the bright part of the display unit to the dark brightness of the screen edge. In this way, although the luminance unevenness at the edge of the display screen remains, it can be made inconspicuous, and the luminance (brightness) of the entire screen can be kept high.

  By the way, even if it is a display device designed for signage in this way, luminance unevenness at the end of the display screen is not noticeable when used alone, but when used as a display device constituting a multi-display, Unevenness is noticeable and easily perceived. This is because the degree of decrease in brightness is different between adjacent display devices, or by displaying one image with a plurality of display devices, the end of the display surface that was not closely watched with one device may be watched. Because it becomes.

  By the way, the display device designed for signage and information display in this way does not notice uneven brightness when used alone, but when used as a display device constituting a multi-display, brightness unevenness is easily noticeable. Become. This is because the degree of decrease in brightness is different between adjacent display devices, or by displaying one image with a plurality of display devices, the end of the display surface that was not closely watched with one device may be watched. Because it becomes.

  Therefore, a user who purchased a display device designed for signage used the display device as a single signage at first, but later changed its use and used it for multi-display. As a result, there arises a problem that uneven brightness is noticeable.

  An object of the present invention is to provide a video processing device, a display device, a program, and a recording medium that can realize video processing suitable for each usage even if the usage of the display device changes.

  In order to achieve the above object, a video processing apparatus according to an aspect of the present invention includes a switching unit capable of switching at least a first mode and a second mode, which are image quality correction modes, in accordance with an input instruction; In any of the cases of the second mode and the second mode, the color unevenness correction for each pixel is performed on the video data of the video to be displayed on the display panel using the color unevenness correction data obtained by executing the calibration process. A correction unit, and in the second mode, the correction unit performs gradation limitation processing for uniformly shifting the gradation value of the video data to the low gradation side for each pixel. The color unevenness correction is performed after suppressing the gradation value to a lower gradation side than the mode.

  In the configuration of the present invention, according to the second mode in which the color unevenness correction is performed after performing the gradation restriction process for shifting the gradation value of the video data to the low gradation side, the color is not performed without the gradation restriction process. The brightness of the entire image is higher than in the first mode, which is either when performing unevenness correction, or when performing gradation unevenness correction by performing gradation restriction processing after suppressing the degree of shift compared to the second mode. It was found that the degree of suppression of pseudo luminance unevenness accompanying the suppression of color unevenness was increased, although it was lowered.

  Therefore, in the configuration of the present invention, in a case where there is a high necessity for performing high luminance display (for example, a case where it is used as a signage), although the degree of pseudo luminance unevenness suppression is suppressed by switching to the first mode, In cases where it is necessary to enable display of the brightness range and suppress uneven brightness (for example, as a display device included in a multi-display), the brightness of the entire image is reduced by switching to the second mode. Although it is lowered, the pseudo luminance unevenness suppression degree can be increased. In other words, high-brightness display can be realized in applications where there is a high need for high-brightness display, and brightness-unevenness suppression can be increased in applications where there is a high need to suppress luminance unevenness, even if the use of the display device changes. There is an effect that it is possible to realize video processing suitable for each application.

  Note that in one aspect of the present invention, the color unevenness correction is performed after performing the gradation restriction process, thereby suppressing the unevenness of color and the effect of artificially suppressing the uneven brightness caused by the suppression of color unevenness. It has the advantage of increasing. Here, since the gradation limiting process uniformly applies the same correction to all pixels, it does not place an excessive burden on the computer. Thus, in the present invention, both color unevenness and luminance unevenness are effectively reduced while suppressing the burden on the computer as much as possible. On the other hand, Patent Document 1 (Japanese Patent Laid-Open No. 2013-97115) does not have the advantage of the present invention because it is not a configuration that performs color unevenness correction in the first place.

It is a block diagram which shows schematic structure of the display calibration system of Embodiment 1. FIG. It is the figure which showed the reference data. It is the schematic diagram which showed the color space (space grid) which made each set of RGB values shown by reference | standard data each grid point. FIG. 4 is a schematic diagram showing a unit cell that belongs to the color space shown in FIG. 3 and includes unit points (192, 192, 192) and (224, 224, 224). Among the data shown in the color unevenness correction table, the data indicates the correction amount for one pixel. Of the data shown in the color unevenness correction table, the data indicates the correction amount for one pixel, and shows an example different from the example of FIG. 5A. This is a color space in which 27 sets of RGB values whose correction amounts are indicated in the color unevenness correction table are shown as grid points. It is the figure which showed the color nonuniformity correction map typically. It is the figure which showed the index map typically. It is the figure which showed the backlight of the display apparatus typically. It is the figure which showed typically the brightness nonuniformity of the display screen in the case of using a display apparatus alone. It is the figure which showed the luminance distribution of the display apparatus at the time of displaying a uniform image | video for every mode, a vertical axis | shaft shows a brightness | luminance and a horizontal axis shows the position on a display screen. It is the figure which compared the grade of the brightness nonuniformity suppression in each mode. It is a figure which shows typically the display screen and luminance distribution at the time of displaying a uniform image | video in each mode in the multi display which arranges the display apparatus of this embodiment. It is the figure which showed the distribution range of the RGB value after adjustment by a gradation restriction | limiting process among the color spaces which show the range of the RGB value which can be displayed in a display apparatus. It is the figure which showed as the color space the range which the RGB value after the adjustment by a gradation limitation process can take. It is the figure which showed the correction value with respect to each input gradation value obtained by spline interpolation. It is a figure which shows typically UI for mode setting. It is a figure which shows typically UI for mode setting, and is a figure which showed the example different from FIG. 17A. It is the figure which showed typically schematic structure of the arrangement | positioning determination system of Embodiment 2. FIG. It is the flowchart which showed the flow of the process performed at the production process of FIG. It is the table | surface which showed the relationship between a mode and a measurement data set. It is the figure which was stored in the installation server of FIG. 18, and showed the database formed by accumulating the measurement data set. It is the flowchart which showed the flow of the process in the installation process of FIG. It is the figure which showed typically the reference area | region set to each display apparatus which comprises the multi display of Embodiment 2. FIG. It is the figure which showed typically the reference area | region set to each display apparatus which comprises the multi display of Embodiment 2, and is the figure which showed the example different from FIG. It is explanatory drawing which showed the outline | summary of the installation process. It is a figure for demonstrating color difference (DELTA) E calculated | required in the optimal arrangement | positioning determination process. It is a figure which shows UI displayed on the monitor of an arrangement | positioning determination apparatus. It is a figure which shows UI displayed on the monitor of an arrangement | positioning determination apparatus, and is a figure which shows the example different from the example of FIG. It is explanatory drawing which shows the object point set when calculating the adjustment value of Embodiment 4.

[Embodiment 1]
Hereinafter, the present embodiment will be described with reference to the drawings. In this embodiment, the color unevenness is a variation in the color of each pixel (such as the chromaticity obtained from the measured value) due to the difference in the characteristics of each pixel due to the structural factors of the display device. It refers to the phenomenon that occurs. In addition, luminance unevenness is a phenomenon in which luminance (measured luminance) decreases as it approaches the edge from the center of the display screen due to differences in backlight characteristics, etc., and differences in characteristics among pixels. This is a phenomenon in which the brightness of each pixel varies due to the above.

(Configuration of display calibration system)
As shown in FIG. 1, the display calibration system 1 of the present embodiment includes a display device 10, a system control device (computer) 40, and a measurement device 50. The display device 10 includes an interface 20, a control unit 25, a storage unit 26, an operation unit 28, and a display unit 14.

  The interface 20 includes a DVI (Digital Visual Interface) terminal 21 and a HDMI (High-Definition Multimedia Interface) terminal 22 for serial communication using a TMDS (Transition Minimized Differential Signaling) method, and a TCP (Transmission Control Protocol) or UDP (User Datagram). A LAN terminal 23, an RS232C terminal 24, and the like for communicating with a communication protocol such as Protocol, and a Display Port terminal (not shown) are included.

  The interface 20 is connected to the DVI terminal 21, the HDMI (registered trademark) terminal 22, the Display Port terminal, the LAN terminal 23, the RS232C terminal 24, or the like in accordance with an instruction from the overall control unit 31 of the control unit 25 described later. Data is sent to and received from the device (peripheral device). The interface 20 may further include a USB terminal and an IEEE 1394 terminal.

  The storage unit 26 is an information storage device such as a hard disk or a semiconductor memory, and stores various data handled by the control unit 25. The control unit (video processing device, control device) 25 is a computer or control circuit that controls the display device 10, and is a general control unit 31, video data processing unit 32, audio signal processing unit 33, panel controller 34, calibration processing unit. 35 and an unevenness correction unit 36.

  The overall control unit 31 is a block that comprehensively controls each hardware of the display device 10. When video data (video data to be displayed on the display unit 14) is input from an external device through the interface 20, the video data processing unit 32 is a block that performs predetermined processing on the video data. Note that the video data handled in the present embodiment is 8-bit digital data, and indicates a gradation value (0 to 255) for each color component of R (red), G (green), and B (blue). And Also, the smaller the gradation value, the darker (the luminance decreases), and the larger the gradation value, the brighter (the luminance increases). The audio signal processing unit 33 is a block that performs predetermined processing on an audio signal input from an external device via the interface 20 (an audio signal output from a speaker of the display unit 14).

  The calibration processing unit 35 obtains a correction amount for color unevenness correction (amount adjusted by correction) for each pixel, and performs a calibration process for creating a color unevenness correction table indicating the correction amount for each pixel. It is. The created color unevenness correction table is stored in the storage unit 26.

  The unevenness correction unit (correction unit) 36 is a block that corrects the video data of the video displayed on the display unit 14 using the color unevenness correction table stored in the storage unit 26. Note that the unevenness correction unit 36 may be configured to perform processing on the video data after the processing by the video data processing unit 32, or perform processing on the video data before the processing by the video data processing unit 32. You may come to do.

  The panel controller 34 controls the display unit 14 to display the video of the video data processed by the video data processing unit 32 and the unevenness correction unit 36 on the display unit 14. Further, the panel controller 34 displays a test image for calibration processing on the display unit 14 in response to an instruction from the system control device 40.

  The operation unit 28 is an operation member for a user to input various instructions. The overall control unit 31 is a block that controls the operation of the display device 10 in response to an input instruction from the operation unit 28 or the remote controller. For example, the overall control unit 31 switches the presence / absence of power supply to each hardware of the display device 10 in accordance with an operation instruction by a power switch included in the operation unit 28.

  The display unit (display panel) 14 is, for example, a liquid crystal display device (LCD), a plasma display panel, an organic EL display device, or the like, and displays images by being controlled by the panel controller 34.

  The measuring device 50 captures a test image displayed on the display screen of the display unit 14, and uses a measurement value (for example, a measured value such as an XYZ value) for each pixel of the measuring device 50 obtained by the capturing as measurement data. It is a device that outputs. The test image is an image in which the input gradation values of the respective color components are the same for all pixels. For example, a test image in which the RGB values of all pixels are (255, 0, 0) is a red test image.

  As the measuring device 50, a luminance and chromaticity measuring device manufactured by Topcon (UA-1000A, etc.), a surface luminance meter such as a two-dimensional color luminance meter (CA-2000, etc.) manufactured by Konica Minolta, Nikon or Sony Corporation. High-definition digital cameras, industrial cameras, etc. can be used.

  The measuring device 50 includes an input / output terminal such as a USB (Universal Serial Bus), and is connected to the system control device 40 via the input / output terminal so as to be communicable.

  The system control device 40 is a control device that controls the display device 10 and the measurement device 50 in order to perform a calibration process. Examples of the system control device 40 include a general-purpose personal computer including a processor and a storage unit.

  The system control device 40 is not only connected to the measurement device 50 so as to be communicable as described above, but is also connected to the display device 10 so as to be communicable via an RS232C terminal or the like. The system control device 40 is installed with an application that communicates with the display device 10 and the measurement device 50 to control these devices.

  When the operator inputs a calibration processing instruction to the system control device 40, the system control device 40 displays a test image on the display device 10 and transmits a measurement request to the measurement device 50. Upon receiving the measurement request, the measurement device 50 takes a test image displayed on the display device 10 and transmits the measurement data to the system control device 40, and the system control device 40 stores the measurement data. The system control device 40 switches test images to be displayed on the display device 10 after storing the measurement data. For example, after displaying a red test image in which the RGB values of all pixels are (255, 0, 0) and storing measurement data for the red test image, the RGB values of all pixels are (0, 255, 0). ) To display the green test image.

  Thereafter, the series of operations of “shooting”, “sending”, “storing”, and “switching test images” are repeated, and the system control is performed as soon as the above-described series of operations are completed for all test images used in the calibration process. The device 40 ends the measurement using the measuring device 50. When the measurement using the measurement device 50 is terminated, the system control device 40 transmits measurement data and an instruction for calibration processing to the display device 10.

  Receiving the measurement data and calibration processing instruction, the overall control unit 31 stores the measurement data in the storage unit 26 and causes the calibration processing unit 35 to perform the calibration processing.

(Calibration processor 35)
Next, the calibration processing unit 35 shown in FIG. 1 will be described. The calibration processing unit 35 inputs the measurement data obtained by the measurement after the measurement of the test image displayed on the display unit 14 is performed by the measurement device 50, and performs the calibration process based on the measurement data. It is a block. In the following description, measurement data obtained from photographing one test image is assumed to be one measurement data. That is, one measurement data is a set of data obtained by photographing one test image, and is a set of measurement values (for example, XYZ values) of each pixel of the measurement apparatus 50.

  First, the calibration processing unit 35 performs an extraction process of extracting a pixel region corresponding to the display screen of the display unit 14 from all the pixels of the measurement data. Note that the calibration processing unit 35 can determine a pixel region corresponding to the display screen of the display unit 14 by comparing each measurement data obtained from each test image and detecting a portion having a different color. .

  Next, the calibration processing unit 35 performs a size adjustment process (interpolation process) for adjusting the size (number of pixels) of the measurement data after the extraction process. This is a measure for matching the number of pixels of the measurement data with the number of pixels of the display screen so that each pixel of the measurement data corresponds to each pixel of the display unit 14 on a one-to-one basis. That is, the measurement value for each pixel of the measurement data after the size adjustment processing corresponds to the measurement value of the display color for each pixel of the display unit 14. The measured value is a value measured by the measuring device 50 or a calculated value obtained by interpolating this value, and tristimulus values (X, Y, Z) are used in this embodiment. That is, the measurement value per pixel of the measurement data is composed of an X value, a Y value, and a Z value.

  Subsequently, the calibration processing unit 35 obtains a correction amount for color unevenness correction for each pixel of the display unit 14 using the measurement data after the size adjustment and the reference data stored in advance. A method for calculating the correction amount will be described later.

  The reference data is data stored in a ROM (not shown) inside the display device 10 when the display device 10 is manufactured, and is data commonly used for all display devices 10 of the same model. . Specifically, as shown in FIG. 2, the reference data is a correspondence relationship between an input gradation value (RGB value) and an XYZ value (reference value) set as a reference for the input gradation value. It is data which shows.

  The reference data is created as follows. First, at the factory, one or several reference machines are selected from among the same types of display devices 10 that are mass-produced, and a reference measuring instrument (reference measuring instrument) is designated. Next, a predetermined number of test images (729 in the example of FIG. 2) are sequentially displayed on the reference machine, and each test image is measured using a reference measuring instrument. Then, a reference value is calculated from the measurement data obtained from the test image, and an input tone value (RGB value) of the test image and a reference value (XYZ value) calculated from the measurement data obtained from the test image A correspondence relationship is generated as reference data. That is, the reference data is data indicating the correspondence between the input gradation value and the reference value for each of a plurality of sets of test images (see FIG. 2).

  There are various methods for calculating the reference value from the measurement data. For example, among the measurement data, an average value of measured values of pixels included in the central portion of the display screen (for example, an area range of 20% of the total display area including the central pixel) can be used as a reference value, An average value of measured values of pixels may be used as a reference value, or a maximum value, a minimum value, or an average value among measured values of all pixels may be used as a reference value.

(Compensation amount calculation method)
Next, how to obtain a correction amount for correcting color unevenness will be described. As described above, when the video data is 8 bits (gradation value is 0 to 255), RGB can be set from nine gradation values of 0, 32, 64, 96, 128, 160, 192, 224, and 255. For all the combinations (9 × 9 × 9 = 729 pairs), the display device 10 holds the reference data indicating the corresponding XYZ values (reference values) (see FIG. 2). However, the number and numerical values of gradation values (may be referred to as pixel values) are not limited to these.

  Here, FIG. 3 shows an RGB color space in which each set of RGB values indicated in the reference data is each lattice point. That is, this color space is composed of 729 lattice points and 512 unit lattices. Note that the values shown at the respective grid points on the color space in FIG. 3 are symbols, and the relationship between the symbols of the respective grid points and the gradation values is as described in the table of FIG. The same applies to FIG. 6). In FIG. 3, lattice points including 96 to 224 in at least one of the RGB values are omitted for the sake of convenience, but actually exist.

  In this embodiment, in the measurement using the measurement apparatus 50, test images are displayed for all combinations of RGB that can be set from the gradation values of 32, 128, and 224 (3 × 3 × 3 = 27 pairs). And measured. That is, a test image is displayed for each of the RGB values (32, 32, 32), (32, 32, 128), (32, 32, 224), ..., (224, 224, 224). It is assumed that measurement data is generated by measuring XYZ values.

  In the following, a process for calculating a correction amount for color unevenness for each pixel from measurement data obtained from a test image with RGB values of (224, 224, 224) will be described as an example (that is, input gradation ( 224, 224, 224) will be described for calculating a correction amount for each pixel).

  When there is color unevenness for each pixel in the display unit 14, the XYZ value (measurement value) of each pixel of the measurement data obtained from the test image with the RGB value (224, 224, 224) is converted into the RGB value by the conversion matrix. When converted, there is a difference between the converted value and (224, 224, 224), and this difference is an amount to be corrected.

  For example, the reference value (XYZ value) corresponding to the RGB value (224, 224, 224) is (557.9, 562.1, 843.3), and the RGB value corresponds to (192, 192, 192). The reference values to be used are (405.7, 406.8, 620.1) (see FIG. 2).

Therefore, when a test image having an RGB value of (224, 224, 224) is displayed and measured, a measurement value of a certain pixel of measurement data is (405.7 ≦ X ≦ 557.9, 406.8 ≦ Y ≦). 562.1, 620.1 ≦ Z ≦ 843.3), the lattice points of (224, 224, 224) and the lattice points of (192, 192, 192) are included in the color space of FIG. A point a indicating the measurement value (Xa, Ya, Za) of the pixel is located in the unit cell (see FIG. 4). Here, the RGB values corresponding to (Xa, Ya, Za) are obtained as (Ra, Ga, Ba), and the RGB values (224, 224, 224) of the test image are used as reference points, and the reference points and (Ra, Ga) , Ba) is a correction amount, and the correction amount is as follows.
R correction amount = 224−Ra Formula D1
G correction amount = 224−Ga Formula D2
Correction amount of B = 224−Ba Expression D3
The calculation of (Ra, Ga, Ba) corresponding to (Xa, Ya, Za) can be performed using a 3 × 3 matrix as shown in Equation 1.

  Here, as the coefficients a to i of the matrix of Equation 1, values defined by standards such as sRGB, AdobeRGB, and CIERGB may be used. However, the coefficients a to i are accurate due to individual characteristics of the display device 10. Conversion may not be performed. Therefore, if the coefficients a to i are obtained by referring to the reference data corresponding to the model of the display device 10 that performs the calibration process, conversion suitable for the characteristics of the individual display devices can be performed. Specifically, if three pairs of RGB values and XYZ values are used in the reference data, the coefficients a to i can be obtained by considering as in Expression 2.

  In order to obtain the coefficients a to i, Equation 2 is transformed into Equation 3 below.

  In Equation 2 or Equation 3, the reference value when the RGB value is (R1, G1, B1) is (X1, Y1, Z1), and the reference value when (R2, G2, B2) is (X2, Y2, Z2). ), (R3, G3, B3), the reference value is (X3, Y3, Z3). Then, as shown in FIG. 4, in the unit cell including the point a indicating (Xa, Ya, Za), three lattice points adjacent to the reference point (224, 224, 224) indicating the RGB value of the test image Are used as (R1, G1, B1) to (R3, G3, B3).

  That is, as shown in FIG. 4, (R1, G1, B1) = (192, 224, 224), (R2, G2, B2) = (224, 192, 224), (R3, G3, B3) = (224 , 224, 192).

  Then, the values of (R1, G1, B1) to (R3, G3, B3) are substituted into Equation 3, and (X1, Y1, Z1) corresponding to (R1, G1, B1) to (R3, G3, B3) ) To (X3, Y3, Z3) are read from the reference data shown in FIG. Thereby, the coefficients a to i are obtained.

  By substituting the obtained coefficient into Equation 1 and substituting the measured values (X, Y, Z) of the test image with the RGB values of (224, 224, 224) into Equation 1, ( Ra, Ga, Ba) is obtained, and the correction amount can be calculated by substituting Ra, Ga, Ba into the above-described equations D1 to D3.

  That is, according to the above procedure, it is detected in which unit cell in the color space (space lattice) shown in FIG. 3 the measurement value of the measurement data when the test image is displayed and measured. Among the detected unit grids, the RGB values and XYZ values of three grid points adjacent to the grid points indicating the RGB values of the test image are read from the reference data, and the coefficients of the conversion matrix are obtained from these values. Then, the measurement values are converted into RGB values using a conversion matrix, and the difference between the RGB values of the test image and the converted RGB values is obtained as a correction amount.

A unit cell including the measurement values (X, Y, Z) is detected as follows. First, for each unit cell belonging to the color space shown in FIG. 3, a combination of the minimum RGB values (R _min , G _min , B _min ) and a combination of the maximum RGB values (R _max , G _min ). _max , B _max ) and reference values corresponding to (R _min , G _min , B _min ) in the reference data (X _min , Y _min , Z _min ) and (R _max , G _{max in the} reference data) , B _max ), which is a reference value corresponding to (X _max , Y _max , Z _max ), is obtained or stored in advance in the storage unit 26. A unit cell satisfying the relationship of (X _min ≦ X ≦ X _max , Y _min ≦ Y ≦ Y _max , Z _min ≦ Z ≦ Z _max ) is defined as a unit cell including the measured values (X, Y, Z). To detect.

  By doing so, the correction amount when the RGB values (224, 224, 224) of the test image are used as the input gradation can be obtained for each pixel. The correction amount is similarly obtained for 26 sets of test images having RGB values other than (224, 224, 224).

  As a result, the RGB values are (32, 32, 32), (32, 32, 128), (32, 32, 224),..., (224, 224, 224) of 27 sets of input gradation values. For the combination, a correction amount is obtained for each pixel.

  Then, as illustrated in FIG. 5A, the calibration processing unit 35 creates correction amount information indicating the correction amount for each set of 27 input gradation values for each pixel. FIG. 5A shows correction amount information per pixel. The calibration processing unit 35 creates a color unevenness correction table in which the correction amount information shown in FIG. 5A is shown for all the pixels, and stores it in the storage unit 26. That is, the information shown in FIG. 5A is correction amount information per pixel, but the correction amount information in FIG. 5A is stored in the storage unit 26 by the number of pixels in the display unit 14.

(Color unevenness correction using color unevenness correction table)
When the image data of the video to be displayed on the display unit 14 is input, the unevenness correction unit 36 performs color unevenness correction using a color unevenness correction table on the RGB values for each pixel. Hereinafter, color unevenness correction using the color unevenness correction table will be described. In the above, an example has been described in which the correction amount is obtained for each pixel for 27 sets of RGB values that can be combined from 32, 128, and 224 (see FIG. 5A). However, for convenience of explanation, 0, 128, and 255 are described below. The correction amount is calculated for each pixel for 27 sets of RGB values that can be combined, and a color unevenness correction table is created. That is, as shown in FIG. 5B, (0, 0, 0), (0, 0, 128), (0, 0, 255), ... (255, 255, 255) per pixel. Correction amounts for 27 sets of input gradation values are obtained, and a color unevenness correction table indicating these correction amounts for each pixel is held in the storage unit 26.

  Here, FIG. 6 shows an RGB color space in which 27 sets of RGB values whose correction amounts are indicated in the color unevenness correction table are shown as grid points. When color unevenness correction processing is performed on a set of RGB values corresponding to each grid point shown in FIG. 6, a correction amount associated with the set of RGB values is read from the color unevenness correction table, and this correction is performed. Color unevenness correction is performed by adjusting the gradation value using the amount.

  On the other hand, when color unevenness correction processing is performed on a set of RGB values other than the set of RGB values corresponding to the 27 lattice points in FIG. 6 (that is, other than the set of RGB values shown in the color unevenness correction table). 6), a grid point around the position indicating the RGB value set to be corrected is detected in the color space of FIG. By performing interpolation using the correction amount, a correction amount for a set of RGB values to be corrected may be obtained, and the gradation value may be adjusted using this correction amount. That is, for a set of RGB values whose correction amount is not indicated in the color unevenness correction table, the correction amount may be obtained by interpolating the correction amount indicated in the color unevenness correction table. As an interpolation method in this case, linear interpolation, spline interpolation, tetrahedral interpolation, or the like can be used.

(Mode switching)
Further, the unevenness correction unit 36 of the present embodiment switches the high luminance mode, the luminance unevenness suppression priority mode, and the intermediate mode so that the degree of pseudo luminance unevenness suppression of the entire display screen changes according to the mode. In addition, color unevenness correction processing is performed. This point will be described in detail below.

  Original color unevenness correction (a form in which color unevenness correction is simply performed without switching modes described below) is mainly intended to suppress color unevenness for each pixel due to variation in specifications of each pixel. It is said. The suppression of luminance unevenness is originally performed by correcting luminance unevenness. Therefore, the original color unevenness correction basically prevents the luminance component from being affected as much as possible. For example, the R, G, and B components are not corrected to be “+10, +8, +9”. In such a case, the R, G, and B components are set to “+1, −1, 0”, respectively. The color unevenness is corrected while suppressing the increase and decrease of the luminance component as much as possible. (Note that even if the color unevenness correction is performed without performing the luminance unevenness correction, the color unevenness is suppressed. As a result, a pseudo luminance unevenness suppression effect is generated).

Next, luminance unevenness will be described. For example, if the luminance level of the display device requiring high brightness as signage and information display is turned 700 cd / m ^2, a value of 700 cd / m ² represents the luminance at all positions of the display screen Instead, it represents the brightness at the center of the display screen, and the brightness at the end of the display screen (near the bezel of the display screen) may be lower than at the center. The reason is as follows.

  As shown in FIG. 9, when LEDs are used as backlights, LEDs are not provided for each pixel, but one LED is often provided as a backlight for several tens to several hundreds of pixels. In view of the structure of the display and the characteristics of the LED backlight, as shown in FIG. 9, since there is a backlight in all directions around the center of the display screen, adjacent LEDs emit light from each other. It can compensate for the drop in brightness. On the other hand, since there is no backlight outside the display screen at the end of the display screen, there is a tendency for the luminance to decrease as compared with the central portion. Therefore, in the display device, normally, the luminance unevenness correction that suppresses the luminance at the central portion is performed so that the luminance at the central portion of the display screen approaches the luminance at the end portion. That is, the brightness difference (brightness unevenness) between the center portion and the end portion is suppressed by intentionally reducing the brightness (brightness) of the entire display screen.

  On the other hand, in the case of signage and information displays, there is a requirement to make the displayed image easier to see even in a bright environment, and to make it easier for people who are far away to see, so the brightness is as high as possible. It is desirable to display. However, in the brightness unevenness correction, the brightness is corrected so that the brightness of the bright portion is close to the brightness of the dark portion, so that the brightness of the entire display screen is kept high and the entire display screen is made uniform by eliminating the brightness unevenness completely. There is a trade-off relationship with doing.

  On the other hand, although depending on the specifications of the display device, the luminance at the edge of the display screen when displaying an image with uniform gradation values is greater than or equal to a predetermined ratio (for example, 90%) of the luminance at the center. For example, even if there is a drop in luminance at the edge of the display screen, it is not so noticeable (see FIG. 10B).

Therefore, for display devices for signage and information displays, the brightness unevenness correction that brings the brightness at the center of the display screen closer to the brightness at the edge is not intentionally performed (or some brightness unevenness correction is performed, but the brightness unevenness is somewhat reduced. Some are set to perform color unevenness correction. In this way, although the luminance unevenness remains, it can be made inconspicuous for use, and the luminance (brightness) of the entire display screen can be kept high. For this reason, the luminance level of the display device for signage and information display if it is 700 cd / m ^2, a value of 700 cd / m ^2, represents the luminance of all the position of the display screen Instead, it represents the brightness at the center of the display screen, and the brightness at the end of the display screen may be lower than that at the center.

  By the way, the display device designed for signage and information display in this way does not notice uneven brightness when used alone, but when used as a display device constituting a multi-display, brightness unevenness is easily noticeable. Become. This is because the degree of decrease in brightness is different between adjacent display devices, or by displaying one image with a plurality of display devices, the end of the display surface that was not closely watched with one device may be watched. Because it becomes.

  In other words, even if it is a display device designed for signage (a display device in which the luminance at the edge of the display unit is lower than the central part), when it is used as a multi-display, it is used for other purposes. It is necessary to improve the degree of luminance unevenness suppression than in the case of.

  On the other hand, the display device 10 of the present embodiment does not employ a configuration in which luminance unevenness correction is performed for each pixel in addition to color unevenness correction, but the mode of the unevenness correction unit 35 that performs color unevenness correction is high. By switching to the luminance mode, the luminance unevenness suppression priority mode, and the intermediate mode, a configuration is adopted in which the degree of pseudo luminance unevenness suppression associated with color unevenness suppression is changed according to the mode.

  Specifically, the display device 10 of the present embodiment includes a high luminance mode with high luminance but low luminance unevenness suppression, a luminance unevenness suppression priority mode with low luminance but high luminance unevenness suppression, and a high luminance mode. Mode intermediate to brightness unevenness suppression priority mode (The brightness of the entire screen is lower than high brightness mode but higher than brightness unevenness suppression priority mode, and the pseudo brightness unevenness suppression degree is higher than that of high brightness mode. 3 modes, which are lower than the luminance unevenness suppression priority mode), and the overall control unit (switching unit) 31 selects one of the three modes according to a user input instruction. One mode is set (the set mode is switched). Thereby, according to a use, the pseudo brightness nonuniformity suppression degree is changed by switching a mode.

  Next, each mode will be described in detail based on FIG. 11 and FIG. FIG. 11 is a diagram showing the luminance distribution of the display device for each mode when a uniform image is displayed. The vertical axis indicates the luminance (measured value), and the horizontal axis indicates the position on the display screen. FIG. 12 is an explanatory diagram comparing the degree of pseudo luminance suppression in each mode.

  In the luminance unevenness suppression priority mode, the gradation correction unit 36 uniformly shifts the gradation value (input gradation value) for each color component before color unevenness correction to each pixel toward the lower gradation side. In this mode, color unevenness correction is performed using a color unevenness correction table that is obtained in advance, and in this embodiment, the tone becomes darker as the gradation becomes lower.

  The high brightness mode is a mode in which the unevenness correction unit 36 performs the color unevenness correction process using the color unevenness correction table without performing the gradation restriction process performed in the brightness unevenness suppression priority mode.

  The intermediate mode is a mode in which the unevenness correction unit 36 performs the gradation restriction process and thereafter performs color unevenness correction using a color unevenness correction table obtained in advance, but the shift in the gradation restriction process is performed. Is a mode in which the degree of correction (correction intensity) is suppressed over the luminance unevenness suppression priority mode.

  Next, the reason why the above-described tone limiting process is performed will be described. Reference numeral 200 in FIG. 12 schematically illustrates a display screen in a case where a uniform image is displayed with the luminance value of the backlight being maximized and the RGB values of all pixels being (255, 255, 255). In addition, in the reference numeral 200 in FIG. 12, even if the pixel at the left end has the highest gradation (255, 255, 255), the luminance level is approximately the same when the pixel at the center is (230, 230, 230). Suppose that only

  In the display screen denoted by reference numeral 200 in FIG. 12, in order to bring the luminance level closer between the end pixel 200b and the central pixel 200a, in addition to color unevenness correction, the luminance unevenness for each pixel or for each block composed of a plurality of pixels. There may be a method of performing correction. However, when mode switching is performed by this method, a table showing the correction amount for luminance unevenness correction for each pixel or block must be stored for each mode, which increases the load on the computer. (The table indicating the correction amount for each pixel has a large amount of information, and storing such a table for each mode increases the load on the computer).

  In contrast, the inventor of the present application uniformly shifts the input tone value of each color component to the lower tone side for all pixels (limits the range that each input tone value can take). When color unevenness correction is performed after performing (for example, gradation adjustment indicated by reference numeral 400 in FIG. 12), if the degree of the shift in the gradation restriction process is changed (the range that each input gradation value can take). As an example, a change is made from the reference numeral 400 to the reference numeral 500 in FIG. Specifically, when the degree of shift of the gradation restriction process is zero (that is, when the gradation restriction process is not performed (when the range that each input gradation value can take is not restricted)), the screen Although the overall brightness is high and the effect of suppressing pseudo brightness unevenness caused by color unevenness correction is low, the degree of shift in the gradation limiting process is high (the range that each input gradation value can take is small). It has been found that the luminance of the entire screen is reduced and the effect of suppressing the pseudo luminance unevenness caused by the color unevenness correction is increased.

  Therefore, in the present embodiment, by changing the degree of gradation restriction processing (correction intensity) by changing the mode (changing the range that each input gradation value can take), a pseudo-occurrence caused by color unevenness correction is generated. The effect of suppressing luminance unevenness is changed by mode switching. In this way, the degree of luminance unevenness suppression can be changed according to mode switching without increasing the load on the computer. The reason why the load on the computer does not increase is as follows.

  In the above-described tone limiting process, if the input tone value is the same for all pixels (reference numeral 200 in FIG. 12), the tone adjustment amount applied to all the pixels is uniformly the same. This can be realized if all the pixels have common input tone value conversion information (parameters, etc.). The input gradation value conversion information common to all the pixels has a small amount of information, and even if such input gradation value conversion information is provided for each mode, the load on the computer does not become so high.

  That is, according to the configuration of the present embodiment, it is necessary to store a color unevenness correction table (high data amount) indicating the color unevenness correction amount for each pixel or group. There is no need to store different color unevenness correction tables for each mode. Further, although it is necessary to store input gradation value conversion information with a low data amount for each mode, there is no need for a luminance unevenness correction table (high data amount) indicating the luminance unevenness correction amount for each pixel or group. Therefore, the load applied to the computer can be suppressed as compared with the case of adopting a method of switching the degree of luminance unevenness correction for each pixel in accordance with the mode switching.

  Next, the gradation restriction process in each of the luminance unevenness suppression priority mode and the intermediate mode will be specifically described.

  As shown in the display screen indicated by reference numeral 200 in FIG. 12, when an image having a uniform RGB value with the highest gradation value is displayed, the luminance level of the pixel 200b at the darkest end is approximately the highest. It is assumed that only the luminance level when the RGB value of the bright central pixel 200a is (230, 230, 230) is reached.

  Therefore, in the luminance unevenness suppression priority mode, when the highest gradation value (255) is input for each color component, it is converted to the gradation value (230) of the pixel 200a corresponding to the luminance level of the pixel 200b at the highest gradation value. It is supposed to be. That is, the gradation value of each color component is converted from 255 to 230 in all pixels.

  More specifically, the gradation restriction process in the luminance unevenness suppression priority mode is performed as follows. First, in the storage unit 26, data indicating the adjusted input gradation value (230) applied to the highest gradation value (255) in the gradation restriction processing in the luminance unevenness suppression priority mode is stored in advance for each color component. (The adjusted input tone value applied to the highest tone value is calculated from the measured value. This point will be described in detail later).

  In the present embodiment, since the maximum gradation value is adjusted from 255 to 230 in the gradation restriction processing in the luminance unevenness suppression priority mode, the adjusted input gradation value (hereinafter referred to as the maximum gradation value) corresponding to the maximum gradation value is set. 230 is stored as simply “adjusted gradation value”.

  The unevenness correction unit 36 reads out the adjusted gradation value corresponding to the highest gradation value for each color component in the luminance unevenness suppression priority mode, and adjusts the lowest gradation value (0) and the adjusted gradation level for the highest gradation value. By linearly interpolating the tone value (230), the adjusted tone values for all the input tone values can be obtained. As a result, gradation restriction processing can be performed.

  Note that the following technique may be used instead of the technique of storing the adjusted gradation value corresponding to the highest gradation value in advance. A coefficient (230/255 (≈0.902)) obtained by dividing the adjusted value of the maximum gradation value by the value before adjustment is stored, and after adjustment for all input gradation values based on this coefficient A gradation value may be obtained. Or you may memorize | store the conversion table which linked | related the input gradation value (0-230) after adjustment with the input gradation value (0-255) before adjustment.

  As a result, it is possible to realize a gradation limiting process that uniformly shifts the input gradation value to the low gradation side for each pixel. The unevenness correction unit 36 performs the color tone correction by referring to the color unevenness correction table after performing the gradation limiting process in this way.

  Next, the intermediate mode will be described. In the intermediate mode, although the gradation adjustment range in the gradation restriction process is not as wide as in the luminance unevenness suppression priority mode, the color unevenness correction is performed after the gradation restriction process. That is, the range that each input gradation value can take in the intermediate mode is set smaller than that in the high luminance mode and wider than the luminance unevenness suppression priority mode.

  Specifically, the gradation limit process in the intermediate mode is performed as follows. First, in the storage unit 26, data indicating the adjusted gradation value applied to the highest gradation value in the gradation restriction process in the intermediate mode is stored in advance for each color component. In the intermediate mode, the adjusted gradation value applied to the highest gradation value is higher than the adjusted gradation value (230) applied to the highest gradation value in the luminance unevenness suppression priority mode, and gradation restriction processing is performed. A value lower than the maximum gradation value (255) in the high luminance mode is set. Here, it is assumed that 240 is set for all color components as the adjusted gradation value for the highest gradation value in the intermediate mode. Then, in the intermediate mode, the unevenness correction unit 36 reads out the adjusted gradation value for the maximum gradation value from the storage unit 26 for each color component, and after adjustment for the minimum gradation value (0) and the maximum gradation value. By performing linear interpolation with the gradation value (240), the function (coefficient representing the slope) indicated by reference numeral 500 in FIG. 12 is obtained, and the gradation restriction processing is performed by adjusting the input gradation value using the function. Do. In the intermediate mode, as in the luminance unevenness suppression priority mode, the adjusted gradation value for the highest gradation value may not be stored, but a coefficient or a conversion table may be stored. The unevenness correction unit 36 performs the color tone correction by referring to the color unevenness correction table after performing the gradation limiting process in this way.

  In the high luminance mode, the color unevenness correction process is performed using the color unevenness correction table without performing the gradation restriction processing performed in the luminance unevenness suppression priority mode and the intermediate mode. That is, the unevenness correction unit 36 performs color unevenness correction using the color unevenness correction table without performing gradation restriction processing on the input gradation value as in the function of reference numeral 300 in FIG. 12 in the high luminance mode. I do.

  Next, features of each mode will be described. As shown in FIG. 11, in the high luminance mode, the luminance of the central portion of the display screen of the display unit 14 can be maintained high, but the luminance of the end portion is lower than the luminance of the central portion. Therefore, when the high luminance mode is used as a multi-display, as shown in FIG. 13, a decrease in luminance is easily perceived in the vicinity of the boundary between the display device and the display device. That is, the high luminance mode is insufficient in terms of uniformity when the display device 10 is used as a multi-display, but is a mode suitable for use as a signage by the display device 10 alone.

  On the other hand, in the luminance unevenness suppression priority mode, as shown in FIGS. 11 and 13, by performing color unevenness correction after performing gradation restriction processing, the luminance unevenness of the display unit 14 is also suppressed and uniform. I make it visible. For this reason, the luminance uniformity is improved, but the luminance of the central portion of the display unit 14 is lowered, and accordingly, the luminance of the entire display screen is lowered. That is, the luminance unevenness suppression priority mode is insufficient in the sense that brightness (luminance) is insufficient when used as a signage by the display device 10 alone, but is a mode suitable when the display device 10 is used as a multi-display. is there.

  In addition, as shown in FIGS. 11 and 13, the intermediate mode is a mode in which image processing is not performed with emphasis only on one of high luminance or luminance unevenness suppression, but both are performed with some consideration. It is. That is, according to the intermediate mode, it is possible to perform display in which the luminance uniformity is improved to some extent while maintaining the luminance of the display screen to some extent.

  In other words, according to the above configuration, the brightness of the entire screen decreases as the adjustment range in the gradation restriction process increases, but the effect of suppressing pseudo brightness unevenness associated with color unevenness correction can be increased. -ing

  In the present embodiment, for each color component, the adjusted gradation value of the highest gradation in the gradation restriction processing in the luminance unevenness suppression priority mode is set to 230, and the adjusted gradation value in the intermediate mode is 240. An example of a method for setting these values will be described below.

For example, as shown by reference numeral 200 in FIG. 12, when a uniform image with the backlight emission luminance being maximized and the RGB values of all pixels being (255, 255, 255) is displayed, The measured value of the luminance of the central pixel 200a having the highest luminance is 1000 (cd / m ² ), whereas the measured value of the luminance of the end pixel 200b having the lowest luminance among all the pixels is 902. It is assumed that (cd / m ² ). Here, the RGB gradation value of the pixel 200a such that the luminance of the pixel 200a is equal to the luminance of the pixel 200b is obtained as the adjusted gradation value. Specifically, assuming that the luminance when the RGB value is (0, 0, 0) is 0 and that a proportional relationship is established between the measured value and the gradation value, all the color components are A common adjusted gradation value can be obtained from Equation 4.
Adjusted gradation value = 255 × (luminance at edge gradation 255−luminance at edge gradation 0) / (luminance at gradation 255 at center− gradation 0 at center) Luminance at the time of
When calculating Equation 4,
Tone value after adjustment = 255 × (902-0) / (1000-0) = 230.01
It becomes. Then, the value is rounded to 230, and the adjusted gradation value applied to the highest gradation value in the luminance unevenness suppression priority mode is stored in the storage unit 26 as 230 for each color component. The adjusted gradation value having a decimal number may be stored in the storage unit 26 without rounding the value, and gradation restriction processing is performed using the adjusted gradation value to perform color unevenness correction. The gradation value may be rounded finally.

  The adjusted gradation value applied to the highest gradation value in the intermediate mode is lower than the highest gradation value (255) in the high luminance mode and is applied to the highest gradation value in the luminance unevenness suppression priority mode. A value higher than the adjusted gradation value (230) is set. For example, an average value of the highest gradation value in the high luminance mode and the adjusted gradation value of the highest gradation value in the luminance unevenness suppression priority mode may be used as the correction value in the intermediate mode (however, in this embodiment, FIG. As indicated by reference numeral 500 of FIG.

  The calculation of the adjusted gradation value is performed by the calibration processing unit 35. That is, the luminance of the display screen is measured by the measuring device 50 capable of measuring the luminance during the calibration process, and the calibration processing unit 35 calculates the adjusted gradation value based on the measurement result and stores it in the storage unit 26. save. Then, the unevenness correction unit 36 obtains the functions and conversion tables indicated by reference numerals 400 and 500 in FIG. 12 by linear interpolation using the adjusted gradation values stored in the storage unit 26, and uses these functions and conversion tables. To perform gradation restriction processing.

  As described above, the adjusted gradation value is obtained from the measurement result obtained by displaying the uniform image (R, G, B) = (255, 255, 255) indicated by reference numeral 200 in FIG. However, if there is a measurement value of an image other than the image of (R, G, B) = (255, 255, 255), the gradation limiting process may be performed in consideration of this measurement value. For example, similar to the above example, the adjusted gradation value of (R, G, B) = (230, 230, 230) is obtained from the measurement result of (R, G, B) = (255, 255, 255). Although calculated, when (R, G, B) = (255, 0, 0) is displayed and measured, after adjustment to the highest gradation value of R for matching the luminance at the center with the luminance at the left end It is assumed that 236 is obtained as the gradation value. In this case, for G and B, as in the above example, the input tone value is adjusted using the function indicated by reference numeral 400 in FIG. 12, but for R, the adjusted tone for the highest tone value A function different from the reference numeral 400 in FIG. 12 may be obtained by linearly interpolating the value 236 and the lowest gradation value 0. Also in this example, a method of storing the adjusted gradation value with respect to the highest gradation value may be employed, or a method of storing a coefficient or a conversion table may be employed. Further, the range of the adjusted gradation value (RGB value) by the gradation restriction process in the luminance unevenness suppression priority mode in this example is distributed in the range indicated by reference numeral 700 in the color space of FIG. Similarly, other colors such as (R, G, B) = (0, 255, 0) and (R, G, B) = (0, 0, 255) are similarly performed, so that the higher Accurate calculation of the adjusted gradation value is possible.

Alternatively, the luminance value is measured not only for the test image having the same gradation value for each color component but also for the test image for which the gradation value is different for each color component, and the gradation value at the left end is (255, 255). It is assumed that the luminance value at the time of 255) is equal to the luminance value at the time when the gradation value at the center is (236, 230, 228).
In this case, the range of the input gradation value from (0, 0, 0) to (255, 255, 255) is adjusted to the range from (0, 0, 0) to (236, 230, 228). However, the combination of RGB values after adjustment with respect to the combination of RGB values before adjustment may be obtained using an interpolation method such as linear interpolation, spline interpolation, and tetrahedral interpolation. In other words, the input tone value is assumed to have been converted into a color space consisting of eight vertices as shown in FIG. 15, and shows a combination of RGB values after conversion in the color space using various interpolation methods. Find the lattice points.

  Further, not only the measurement result for the image having the highest gradation value [that is, (R, G, B) = (255, 255, 255)], but also the image [for example, (R, G, B) other than the highest gradation value. = (192, 192, 192), (128, 128, 128), (64, 64, 64), etc.] may be used to perform gradation restriction processing. For example, in each color component, 230 is obtained as the adjusted gradation value with respect to the gradation value 255 in order to bring the luminance of the center portion of the display screen closer to the luminance of the end portion by the method using Equation 4 above. Assume that 142 is obtained as the adjusted gradation value for the tone value 192, 116 is obtained as the adjusted gradation value for the gradation value 128, and 52 is obtained as the adjusted gradation value for the gradation value 64. . In this case, as shown in FIG. 16, the adjusted gradation value for each input gradation value can be obtained from the adjusted gradation value obtained discretely by spline interpolation or the like.

  In this way, gradation restriction processing is performed, and color unevenness correction is performed based on the converted input gradation value. In other words, even if the mode changes, the input gradation value only changes due to the gradation restriction process, and the same conversion table is used to perform color unevenness correction. Is done.

(Modification of Embodiment 1)
A modification regarding the color unevenness correction table will be described. The correction amount information shown in FIG. 5A or 5B is for one pixel, and the correction amount is shown for each of the 27 sets of RGB values. That is, 81 correction amounts are shown per pixel (27 × 3 = 81).

  In the first embodiment, a color unevenness correction table showing the correction amount information for all the pixels of the display unit 14 is stored in the storage unit 26. However, when the display unit 14 is a display panel having a high pixel count of, for example, 1920 pixels × 1080 pixels, correction amount information including 81 correction amounts needs to be stored for 1920 pixels × 1080 pixels and should be saved. The data capacity becomes very large. Therefore, instead of holding correction amount information for all pixels as a color unevenness correction table, it is possible to reduce the data capacity by creating an index map and a color unevenness correction map as described below. .

  When the calibration processing unit 35 obtains correction amount information indicating correction amounts for 27 sets of RGB values per pixel shown in FIG. 5A or 5B for all pixels, the correction amount information for all pixels is obtained by clustering, for example, Group into 256 groups. Next, the calibration processing unit 35 extracts correction amount information that is representative of each group (one correction amount information is extracted per group). Subsequently, the calibration processing unit 35 stores in the storage unit 26 a color unevenness correction map (see FIG. 7) in which the extracted 256 correction amount information and the identification number of each correction amount information are associated with each other. Further, the calibration processing unit 35 creates, for each pixel, an index map (see FIG. 8) indicating an identification number corresponding to the correction amount information extracted from the same group as the correction amount information of each pixel. The map is also stored in the storage unit 26. Then, the unevenness correction unit 36 refers to the index map of the storage unit 26, reads the identification number assigned to the pixel to be corrected, reads the correction amount information of the identification number from the color unevenness correction map, The correction amount is obtained from the correction amount information, and the gradation value is corrected. In this way, correction amount information for all pixels is not held as a color unevenness correction table, but correction amount information for 256 pixels extracted from correction amount information for all pixels is held. Therefore, the data capacity can be reduced. In addition, since grouping is performed by clustering, when correction is performed for a certain pixel, correction is performed using correction amount information similar to the correction amount information of the pixel (with a small error). Therefore, it is possible to suppress the correction accuracy to a level with no problem (a level that cannot be recognized by human eyes).

  That is, in the modification example in which the index map and the color unevenness correction map are created, the color unevenness correction data is not included in each pixel but is included in each group of pixels.

  In the above embodiment, as shown in FIG. 5A or FIG. 5B, the correction amount for the 27 RGB values is calculated by measuring 27 test images in the calibration process, and the color unevenness correction table is calculated. It is not necessary to have 27 sets. 125 sets obtained by combining five gradation values such as 0, 64, 128, 192, and 255, or four gradation values such as 32, 96, 160, and 224 may be combined. 64 sets may be used.

  In the embodiment described above, the display device 10 has only one intermediate mode. However, the display device 10 may have a plurality of intermediate modes having different degrees of adjustment. In this way, basically you want to maintain high brightness, but you want to suppress uneven brightness even slightly, or conversely, you want to suppress brightness unevenness but want to increase brightness even slightly. It is possible to cope with such a case.

  Alternatively, the intermediate mode adjustment level (correction strength) may be made variable so that a plurality of intermediate modes having different adjustment levels may be provided (that is, the intermediate mode adjustment level is switched in a plurality of stages). If possible, it will have substantially multiple intermediate modes).

  For example, the overall control unit (switching unit) 31 may display the level setting UI illustrated in FIG. 17A on the display unit 14. The level setting UI in FIG. 17A is a dialog box for inputting a numerical value indicating the adjustment level. A numeric value from 0 to 1 can be input to this UI. The overall control unit 31 sets the luminance unevenness suppression priority mode when 0 is input, and sets the high luminance mode when 1 is input. Further, when a value (decimal number) greater than 0 and smaller than 1 is input, the overall control unit 31 sets an intermediate mode with an adjustment level corresponding to the input value.

When the intermediate mode in which the adjustment level is variable is set, the calibration processing unit 35 or the unevenness correcting unit 36 performs input gradation limitation in the intermediate mode as follows. First, as a premise, gradation limitation processing is not performed in the high luminance mode, and in the luminance unevenness suppression priority mode, the adjusted gradation value for the highest gradation is set to 230, and the function of reference numeral 400 in FIG. It is assumed that the gradation limiting process is performed as described above.
Here, the adjusted gradation value of the highest gradation value of the intermediate mode is smaller than the highest gradation value (255) of the high luminance mode, and the adjusted gradation value of the highest gradation value of the luminance unevenness suppression priority mode (230). ) Will be bigger. Accordingly, if the value indicating the adjustment level (value indicating the degree of brightness) shown in FIG. 17A is K (0 to 1), the adjusted gradation value of the maximum gradation value in the intermediate mode is
Tone value after adjustment of maximum gradation value in intermediate mode = {(maximum gradation value in high luminance mode) − (gradation value after adjustment of maximum gradation value in luminance unevenness suppression priority mode)} × K + luminance unevenness suppression Tone value after adjustment of maximum tone value in priority mode Equation 5
It is expressed.
Substituting the adjusted gradation value of the maximum gradation value of the high luminance mode and the maximum gradation value of luminance unevenness suppression into Equation 5,
The gradation value after adjustment of the maximum gradation value in the intermediate mode = (255-230) × K + 230
It becomes. That is, the intermediate mode can be adjusted to various levels simply by changing the value (K) indicating the adjustment level shown in FIG. 17A.

  Alternatively, an intermediate mode of the adjustment level K may be realized as follows. Corresponds to the gradation value P after color unevenness correction corresponding to the highest gradation value (255) in the high luminance mode and the adjusted gradation value (230) applied to the highest gradation value in the luminance unevenness suppression priority mode. The gradation value Q after color unevenness correction is obtained from the color unevenness correction table. Then, the gradation value after color unevenness correction in the intermediate mode may be directly obtained by the following formula 5A.

Correction value after color unevenness correction in intermediate mode = Q + (P−Q) × K Equation 5A
In the UI shown in FIG. 17A, a value of 0 to 1 including a decimal number is input. However, a percentage value may be used. In this case, 0 (minimum) to 100 (maximum) may be used. ) Is entered. Alternatively, as shown in FIG. 17B, the adjustment level when the luminance unevenness suppression priority mode is set may be 100 (maximum value), and the adjustment level when the high luminance mode is set may be 0 (minimum value). In order to make the level visually understandable, the intermediate mode and the adjustment level may be set by adjusting the position with a slider. At this time, locations that can be set by the slider may be determined in advance, such as “0, 25, 50, 75, 100”.

  In the first embodiment described above, the three modes of the high luminance mode, the intermediate mode, and the luminance unevenness suppression priority mode are provided, but it is only necessary to have at least two modes. In other words, one embodiment of the present invention includes first and second modes that perform color unevenness correction, and in the second mode, the gradation value of the video data is uniformly reduced for each pixel. It is only necessary that the gradation value is suppressed to the lower gradation side than in the first mode by performing gradation restriction processing that shifts to the side.

  Here, in the first embodiment, the high luminance mode corresponds to the first mode, and the luminance unevenness suppression priority mode corresponds to the second mode. In the first embodiment, the color unevenness correction is performed without performing the gradation restriction process in the high luminance mode (first mode).

  In the first embodiment, an intermediate mode (third mode) in which the color unevenness correction is performed after the gradation restriction process is performed while suppressing the degree of shift compared to the luminance unevenness suppression priority mode (second mode). Can also be switched.

  Note that the first and second modes do not necessarily have to be a pair of a high luminance mode in which gradation limitation processing is not performed and a luminance unevenness suppression priority mode in which gradation limitation processing is performed. For example, the pair of the intermediate mode and the luminance unevenness suppression priority mode may be the first and second modes. In this case, both the intermediate mode (first mode) and the luminance unevenness suppression priority mode (second mode) perform the gradation limiting process, but the intermediate mode (first mode) prioritizes luminance unevenness suppression. The gradation limiting process is performed while suppressing the degree of gradation value shift compared to the mode (second mode), and the luminance unevenness suppression priority mode (second mode) is more than the intermediate mode (first mode). The gradation value is suppressed to the low gradation side.

  In addition to the intermediate mode A (first mode) and the luminance unevenness suppression priority mode (second mode), the mode is switched to the intermediate mode B (third mode). The intermediate mode B (third mode) After performing the gradation restriction process with the degree of shift being strengthened compared to the intermediate mode A (first mode) while suppressing the degree of shift more than the suppression priority mode (second mode), the color unevenness correction is performed. You may come to give.

  Of course, the first and second modes may be a pair of a high luminance mode and an intermediate mode. Further, the display device 10 may include only the intermediate mode in which the adjustment level is variable without including the high luminance mode and the luminance unevenness suppression priority mode. In this case, if the intermediate mode of the first adjustment level is set to the first mode, the intermediate mode of the second adjustment level in which the degree of shift in the gradation limiting process is stronger than the first adjustment level is the second mode. Become.

(Other)
When it is determined that the luminance is relatively uniform, as the color unevenness correction, for example, the color unevenness can be corrected by performing a relative correction using correction amounts of “+1, −1, 0”. it can. However, when the luminance is relatively non-uniform, the above method may not correct color unevenness. Therefore, in such a case, in consideration of both luminance unevenness and color unevenness, for example, an absolute correction may be performed using a correction amount of “+10, +8, +9” (absolutely When the correction is performed, a correction table is created separately from the relative correction (color unevenness correction is performed using any one of the correction tables).

[Embodiment 2 (reference example)]
The second embodiment relates to an arrangement determination device 600 that determines the optimum arrangement of the display device 10 in a multi-display in which the display devices 10 of the first embodiment are arranged. In the present embodiment, the display device 10 has the three modes of the high luminance mode, the luminance unevenness suppression priority mode, and the intermediate mode described with reference to FIG. 12, and the adjustment level of each mode is constant. Assuming that. That is, in the modification of the first embodiment, the adjustment level of the intermediate mode may be variable. However, in the display device 10 of the present embodiment, the adjustment level is not variable but is stored in the storage unit 26 in advance in the intermediate mode. It is assumed that the function of FIG. 12 is obtained by linear interpolation or the like using the adjusted gradation value with respect to the highest gradation value, and gradation restriction processing is performed by this function.

  FIG. 18 is a schematic configuration diagram of an arrangement determination system using the arrangement determination apparatus 600 and the installation server 601 according to the present embodiment. As shown in the figure, the arrangement determination system includes a measurement device 50 and a system control device 40 used in the production process, an arrangement determination device 600 used in the installation process, a system control device 40 and an arrangement determination. And an installation server 601 that transmits and receives data to and from the apparatus 600. Each of the system control device 40, the arrangement determination device 600, and the installation server 601 is a general-purpose personal computer.

(About production process)
In the production process of FIG. 18, the display device 10, the measurement device 50, and the system control device 40 of FIG. 1 described in the first embodiment are used. That is, in the production process of FIG. 18, measurement is performed by displaying a test image on the display device 10, and the calibration processing unit 35 performs a calibration process based on the measurement result to create a color unevenness correction table. Save in the storage unit 26. At this time, the calibration processing unit 35 calculates parameters (correction values for the highest gradation) used in each of the luminance unevenness suppression priority mode and the intermediate mode and stores them in the storage unit 26. Furthermore, in this embodiment, measurement is performed by displaying a test image in each of the luminance unevenness suppression priority mode, the intermediate mode, and the high luminance mode, and the measurement result obtained for each mode is used as arrangement determination data (measurement data set). To store in the installation server 601. FIG. 19 is a flowchart showing the flow of processing in the above production process. Hereinafter, the process in the production process will be described in detail with reference to FIG.

  First, it is assumed that the display device 10 to be processed is initially set to a through mode (mode 0) in which no processing by the unevenness correction unit 36 is performed. The system control device 40 inputs the identification number of the display device 10 to be processed by a user operation (S11).

  In S12 to S14, processing similar to the measurement and calibration processing described in the first embodiment is performed. That is, in S12, the system control device 40 displays the test image on the display device 10 and causes the measurement device 50 to measure the color of the display image (S12). In this measurement, a test result is obtained by photographing each test image while sequentially displaying each of N (for example, N = 27) test images having different colors.

  Subsequently, the system control device 40 collects N measurement results (XYZ values) obtained by displaying N (N colors) test images as a measurement data set 0 (S13). In the present embodiment, N (N colors) test images include (R, G, B) = (255, 255, 255) test images, and the measurement results include It is assumed that the luminance value is included in addition to the XYZ value. The measurement data set 0 is temporarily stored in the system control device 40 in association with the identification number input in S11.

  Subsequently, the system control device 40 transmits a calibration processing instruction to the display device 10 together with the measurement data set 0. As a result, the calibration processing unit 35 of the display device 10 performs a calibration process using the measurement data set 0 and the reference data of FIG. 2, and calculates a correction amount for correcting color unevenness for each pixel (S14). The contents of the calibration process are as described in the first embodiment.

  The calibration processing unit 35 stores a set of correction amounts for 27 colors calculated from the measurement data set 0 in the storage unit 26 as a color unevenness correction table.

  In S14, the calibration processing unit 35 performs a process of calculating a parameter (correction value for the highest gradation value) used in each of the luminance unevenness suppression priority mode and the intermediate mode in addition to the calibration process. Store in the storage unit 26. The parameter calculation process is as described in the first embodiment. That is, it can be calculated using the measurement value (luminance value) of the test image of (R, G, B) = (255, 255, 255) and the equation 4 of the first embodiment. Of course, the relationship between the gradation values before and after the adjustment shown in FIG. 12 may be held in the storage unit 26 as a one-dimensional lookup table.

  When S14 ends, the system control device 40 changes the mode set in the display device 10 (S15). Specifically, the system control device 40 switches the mode of the display device 10 from the through mode (mode 0) to the high luminance mode (mode 1).

  In the display device 10 switched to the high luminance mode, the unevenness correction unit 36 operates, and when video data (including test image data) is input, the unevenness correction unit 36 Color unevenness correction is performed in the high luminance mode (that is, the display device 10 is calibrated).

  When the mode is switched in S15, the system control device 40 displays the test image on the display device 10 and causes the measurement device 50 to measure the color of the test image (S16). That is, in S12, a display device that has not been calibrated (a display device that displays a non-uniformity-corrected image) is measured, whereas in S16, a calibrated display device (a non-uniformity-corrected image is displayed). Display device). That is, when the high luminance mode is set, the test image on which the color unevenness correction is performed in the high luminance mode by the unevenness correcting unit 36 is displayed on the display unit 14.

  In S16, each test image is photographed while obtaining each of M (M <N: for example, M = 10) test images having different colors, and a measurement result is obtained.

  After S16, the system control device 40 collects the measurement results in the high luminance mode (mode 1) as the measurement data set 1 (S17). That is, M measurement results (XYZ values) obtained by displaying M (M colors) test images in S <b> 17 are grouped as a measurement data set 1. The measurement data set 1 is temporarily stored in the system controller 40 in association with the identification number input in S11.

  After S17, the system control device 40 determines whether or not creation of the measurement data set has been completed for all modes (high luminance mode, intermediate mode, luminance unevenness suppression priority mode) (S18).

  If not completed (NO in S18), the system control device 40 returns to S15, switches the mode of the display device 10 to a mode in which no measurement data set has been created, and performs the processing subsequent to S16 again. The high luminance mode is switched to the intermediate mode (mode 2), and the intermediate mode is switched to the luminance unevenness suppression priority mode (mode 3).

  In the intermediate mode or the luminance unevenness suppression priority mode, a test image in which the color unevenness correction is performed in each mode by the unevenness correction unit 36 is displayed on the display unit 14 in S16. That is, the color unevenness correction is performed after the gradation limiting process is performed. In the intermediate mode, the measurement data set 2 is created in S17, and in the luminance unevenness suppression priority mode, the measurement data set 3 is created in S17.

  After creation of measurement data sets for all modes is completed (YES in S18), the system control device 40 associates the identification numbers with the measurement data sets 0 to 3 and transmits them to the installation server 601 (S19). Complete the process.

  FIG. 20 is a table showing the relationship between each mode and the measurement data set. The measurement data set 0 is data indicating measurement results when the color of the test image displayed in the through mode (mode 0) in which the unevenness correction unit 36 is not operated is measured. The measurement data set 1 is data indicating a measurement result when the color of the test image displayed in the high luminance mode (mode 1) in which color unevenness correction is performed without performing the gradation restriction process. The measurement data set 3 is data indicating measurement results when the color of the test image displayed in the luminance unevenness suppression priority mode (mode 3) in which the color unevenness correction is performed after the gradation restriction process is performed. Measurement data set 2 is a test that is displayed in an intermediate mode (mode 2) in which gradation unevenness correction is performed after gradation restriction processing, but the adjustment range in gradation restriction processing is suppressed compared to luminance unevenness suppression priority mode. It is data which shows the measurement result at the time of measuring the color of an image.

  Next, information stored in the installation server 601 will be described. FIG. 21 is a diagram showing a database stored in the storage unit of the installation server 601 and accumulating measurement data sets. In the database shown in FIG. 21, the identification number of the display device 10, the measurement data set 0 in the through mode, the measurement data set 1 in the high luminance mode, the measurement data set 2 in the intermediate mode, and the luminance unevenness suppression priority mode. Are stored in association with each other.

  That is, in the production process, the processing of FIG. 19 is sequentially performed for each display device 10 that is mass-produced, and information in which the identification number and the measurement data sets 0 to 4 are associated with each display device is accumulated in the installation server 601. It has come to be.

(About the installation process)
When a multi-display is configured by arranging display devices 10 having a plurality of modes having different degrees of unevenness correction, a certain arrangement pattern may be optimal in one mode but not optimal in another arrangement pattern. . This is because the degree of unevenness suppression in each mode is slightly different in each display device 10. Therefore, when installing a multi-display composed of the display device 10, it is necessary to determine an optimum arrangement for a mode set at the time of installation.

  Therefore, in the present embodiment, in the installation process shown in FIG. 18, the optimal layout according to the mode set when installing the multi-display 1000 in which the display devices 10 are arranged is determined as an arrangement determination device 600 (for example, a notebook PC). Is to judge. That is, software for determining the optimum arrangement is installed in the arrangement determining apparatus 600. In the present embodiment, as shown in FIG. 18, an example in which a multi-display 1000 is configured by arranging a total of four display devices 10 in a vertical direction and two in a horizontal direction and arranging them in a 2 × 2 arrangement. explain. However, the number of the horizontal direction and the vertical direction of the display apparatus 10 which comprise the multi display 1000 is not limited to this.

  FIG. 22 is a flowchart showing the flow of processing in the installation process. First, the arrangement determination device 600 inputs the identification number of the display device 10 to be installed by the operator's operation (S21). Subsequently, the arrangement determining apparatus 600 accesses the installation server 601 and receives the measurement data sets 0 to 4 associated with the identification numbers input in S21 from the installation server 601 (S22). For example, if there are four display devices 10 constituting the multi-display 1000, the identification numbers of the four display devices 10 are input in S21, and the measurement data sets of the four display devices 10 are input in S22. It is downloaded to the arrangement determination device 600.

  Subsequently, the arrangement determining apparatus 600 inputs a mode number to be set for each display apparatus 10 when the multi-display 1000 is installed by a user operation (S23). Specifically, a number indicating any one of the above-described through mode, high luminance mode, intermediate mode, and luminance unevenness suppression priority mode is input. Note that the display device 10 of the present embodiment can also set the through mode. In this case, the display device 10 causes the display unit 14 to display an image without performing the processing by the unevenness correction unit 36. It will be. That is, in an extremely rare case, when the through mode is set for each display device 10 at the time of installation, the through mode number is input in S23.

  After S23, the arrangement determining apparatus 600 determines the optimum arrangement of the display apparatus 10 using the measurement data set corresponding to the mode of the mode number input in S23 among the measurement data sets received in S22. Optimal placement determination processing is performed (S24). Details of the optimum arrangement determination process in S24 will be described later.

  After S24, the arrangement determining apparatus 600 displays a recommended arrangement example indicating the identification number and arrangement position (coordinate value) of the display device 10 on the monitor of the arrangement determining apparatus 600 (S25). For example, as indicated by reference numeral 850 in FIG. 25, the identification number (XX0001, XX0003, XX0016, XX0020) of each display device 10 and coordinate values ((1, 1) (1, 2) (2, 1) (2, 2)) and the layout of each display device are displayed on the monitor. Alternatively, as indicated by reference numeral 851 in FIG. 25, the correspondence between the identification number of each display device 10 and the coordinate value indicating the arrangement of each display device 10 may be displayed.

  Next, the configuration of the arrangement determining apparatus 600 will be described with reference to FIG. The arrangement determination device 600 is a general-purpose computer including a processor and a storage device. As shown in FIG. 25, the arrangement determination apparatus 600 includes a measurement data acquisition unit 600a, a mode selection unit 600b, a determination unit 600c, and a result output unit 600d. In addition, each part 600a-600d included in the arrangement | positioning determination apparatus 600 is a functional block which shows the function implement | achieved by software.

  The measurement data acquisition unit 600a is a block that downloads a measurement data set associated with the identification number from the installation server 601 when the identification number of each display device 10 is input by the user. The mode selection unit 600b selects a mode having a mode number input by the user. The determination unit 600c performs an optimum arrangement determination process using a measurement data set corresponding to the mode selected by the mode selection unit 600b. The result output unit 600d displays the determination result of the optimal arrangement determination process on the monitor of the arrangement determination apparatus 600.

(Optimum placement determination process)
Next, the optimum arrangement determination process in S24 of FIG. 22 will be described in detail. The optimal arrangement determination process can be realized by a known method, and in this embodiment, the method described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2014-26120) is used. Specifically, it is performed as follows.

  First, as illustrated in FIG. 23, the determination unit 600c sets nine reference areas in each display device 10. Specifically, the display screen is divided into nine, and an area composed of 200 × 200 pixels included in each divided area is set as a reference area. Note that the size of the reference region is not limited to 200 × 200 pixels, and can be changed as appropriate.

  Next, the determination part 600c detects the measurement data set corresponding to the mode of the mode number input in S23 of FIG. 22 among the downloaded measurement data sets 0 to 3. For example, when the mode number 3 (luminance unevenness suppression priority mode) is input in S23, the measurement data set 3 is detected.

  Subsequently, the determination unit 600c selects one of the M colors (or N colors) indicated in the detected measurement data set. The color to be selected may be set in advance or may be determined by an input instruction from an operator of the arrangement determination apparatus 600. Here, it is assumed that (R, G, B) = (255, 255, 255) is selected.

For the selected color (R, G, B) = (255, 255, 255), the determination unit 600c represents the representative value of the measurement value for each reference area of each display device 10 (the average value of the measurement values of each pixel). Etc.). The measured value is an XYZ value, but the calculated representative value is converted into an L ^* a ^* b ^* value (L ^* a ^* b ^* data of CIE 1976).

  Next, the determination unit 600c obtains a color difference ΔE between reference regions facing each other across the boundary between two adjacent display devices with respect to one arrangement pattern among all the arrangement patterns that can be set. The color difference ΔE is obtained using the representative value calculated from the measured values corresponding to the selected color (R, G, B) = (255, 255, 255).

Specifically, considering the arrangement pattern shown in FIG. 26 as an example, twelve color differences of ΔE1 to ΔE12 are obtained. Here, ΔE1 is the color difference between the reference region C of the display device 10a and the reference region A of the display device 10b, ΔE2 is the color difference between the reference region F of the display device 10a and the reference region D of the display device 10b, and ΔE3. Is the color difference between the reference area I of the display device 10a and the reference area G of the display device 10b. ΔE7 to ΔE9 are color differences between the reference regions of the display device 10c and the reference regions of the display device 10d, similar to ΔE1 to ΔE3.
ΔE4 is the color difference between the reference region G of the display device 10a and the reference region A of the display device 10c, and ΔE5 is the color difference between the reference region H of the display device 10a and the reference region B of the display device 10c, and ΔE6. Is the color difference between the reference area I of the display device 10a and the reference area C of the display device 10c. Similarly to ΔE4 to ΔE6, ΔE10 to ΔE12 are color differences between the reference areas of the display device 10b and the reference areas of the display device 10d.

  The determination unit 600c specifies the maximum value of ΔE1 to ΔE12 obtained as described above for one arrangement pattern as the maximum color difference ΔE. Such a maximum color difference ΔE is obtained for each of all possible arrangement patterns. The determination unit 600c determines the arrangement pattern having the smallest maximum color difference ΔE as the optimum arrangement.

  As described above, according to the present embodiment, the optimum arrangement is determined based on the measurement value obtained by measuring the test image displayed in the mode set at the time of installation. . Therefore, there is an advantage that an optimum arrangement for a mode set at the time of installation can be determined for a multi-display using a display device having a plurality of modes having different degrees of unevenness correction.

  In the above embodiment, the optimum placement is determined using the placement determination device 600 in the installation process. Of course, the optimum placement can be determined even when the mode needs to be switched after the installation. It is. That is, it is assumed that a multi-display composed of a plurality of display devices 10 is installed, the mode is set, and the use is started. After that, when it becomes necessary to switch the mode, the arrangement determination apparatus 600 may download the measurement data set from the installation server 601 and perform the optimum arrangement determination process. That is, according to the arrangement determination apparatus 600 of the present embodiment, an optimum arrangement for the changed mode can be specified every time the mode is changed.

  Moreover, according to the above embodiment, the test image displayed after setting each mode is measured, and optimal arrangement | positioning is determined based on the measured value obtained by this measurement. That is, the optimum arrangement is determined using the measured value of the test image corrected by the unevenness correction unit 36. Therefore, compared with a system that makes arrangement determination based on a measurement result measured without unevenness correction, it is possible to suppress complication of calculation and improve determination accuracy.

  Moreover, according to the above embodiment, once the measurement data set is stored in the installation server 601 in the installation process, the measurement data set can be used any number of times later. For this reason, once the multi-display 1000 is installed, the mode to be set is switched. Therefore, even if it is necessary to perform the determination again by the arrangement determination device 600, the measurement data set can be downloaded from the installation server 601 again. As a result, it is possible to save the trouble of making new measurements at the installation site.

  Moreover, even if it becomes necessary to replace the display device 10 due to a malfunction of some of the display devices 10 after the multi-display is installed, it is possible to determine an optimal arrangement each time.

  In the above embodiment, the reference area is set as shown in FIG. 23, but the embodiment is not limited to the form shown in FIG. For example, as shown in FIG. 24, a configuration in which rectangular reference regions whose long sides are in the direction parallel to the bezel may be arranged in the vicinity of the bezel.

  In the above embodiment, M (M colors) test images are displayed and measured in S <b> 16 of FIG. 19, but M may be 1. For example, measurement may be performed only for white ((R, G, B) = (255, 255, 255)), or high-intensity gray ((R, G, B) = (240, 240, 240)) may be tested only. In this case, of course, the process of selecting one of the M colors in S24 of FIG. 22 is omitted, and the measurement data set of one color measured in S16 of FIG. 19 is used. It will be.

  Further, the value of M may be different for each mode. For example, measurement may be performed for five colors in the high luminance mode (mode 1), measurement for two colors in the intermediate mode (mode 2), and measurement for three colors in the luminance unevenness suppression priority mode.

  In addition, the arrangement determining apparatus 600 may display a UI as shown in FIG. 27 on a monitor, and input information and output a determination result by this UI. The operator inputs the identification number and mode number of each display device 10 via the UI of FIG. In addition, the operator inputs the number of monitors arranged from the pull-down menu, and selects the installation direction with a button. When the operator finishes inputting all information, the operator presses the execution button. When the execution button is pressed, the determination unit 600c makes a determination, and the result output unit 600d reflects the determination result on the UI. In the UI of FIG. 27, a layout (symbol 450a) indicating the arrangement of display devices with identification numbers ([001]... [004]) is displayed, and the correspondence between the identification numbers and position numbers of the display devices. The relationship (reference numeral 450b) is displayed.

[Embodiment 3 (reference example)]
The third embodiment is a form corresponding to a modification of the second embodiment. In the second embodiment, the measurement data sets 0 to 4 of each display device 10 are stored in the storage unit of the installation server 601, but the measurement data sets 0 to 4 of each display device 10 are stored in the installation server 601. You may make it memorize | store in the memory | storage part 26 of each display apparatus 10 instead of memorize | storing in a memory | storage part. In the third embodiment, the measurement data sets 0 to 4 of each display device 10 are stored in the storage unit 26 of each display device 10. Hereinafter, this embodiment will be described.

  In the present embodiment, in S19 of FIG. 19, the measurement data sets 0 to 3 are not transmitted from the system control device 40 to the installation server 601 but are transmitted to the display device 10 and stored in the storage unit 26 of the display device 10. Is done. In addition, about the measurement data set 0, since it is transmitted to the display apparatus 10 between S13 and S14, transmission can be abbreviate | omitted in S19.

  The installation process is performed as follows. First, each display device 10 used in the multi-display 1000 and the arrangement determination device 600 are connected so as to be able to communicate with each other by a LAN cable or the like. Thereby, the arrangement determination device 600 can read the combination of the identification number of each display device 10 and the measurement data sets 0 to 4 of each display device 10 from each display device 10.

  Alternatively, an external storage device such as a USB memory is used to transmit the combination of the identification number of the display device 10 and the measurement data sets 0 to 4 of the display device 10 from each display device 10 to the arrangement determination device 600. May be. In this case, each display device 10 is provided with a processing unit (software) for writing the measurement data sets 0 to 4 and the identification number stored in the storage unit 26 into the USB memory when it is detected that the USB memory is inserted. It has been.

  When the combination of the identification number of each display device 10 and the measurement data sets 0 to 4 is taken into the arrangement determining apparatus 600 as described above, the arrangement determining apparatus 600 executes S23 to 25 in FIG. The arrangement is determined and the determination result is output. In this way, when configuring a multi-display, the optimum arrangement determination process may be performed using the measurement value data set stored in the storage unit 26 of each display device 10 to be used.

  According to this embodiment, in addition to the advantages of the second embodiment, there are advantages described below. When making a determination using the arrangement determination apparatus 600 at the installation site, an access environment to an external network is not necessary, and therefore the determination can be performed even in an environment where the communication environment is not prepared.

[Embodiment 4 (reference example)]
Even if the optimum arrangement is determined as in the second and third embodiments, the optimum arrangement is merely an arrangement that is most likely to suppress unevenness (brightness or color gap) between display devices. Even if it is arranged according to the arrangement, unevenness is not completely eliminated.

  Therefore, in the present embodiment, the arrangement determination device 600 is provided with an adjustment value calculation unit (not shown). Then, when the adjustment value calculation unit is arranged in an optimal arrangement between S24 and S25 in FIG. 22, an adjustment value for making the gap near the bezel of each display device 10 less noticeable for each display device. Is calculated and set.

  The adjustment value is an adjustment amount applied to a reference gradation (a set of reference RGB values). The reference gradation is set in advance by the manufacturer, and is (255, 255, 255) in this embodiment. The adjustment value calculation unit obtains an adjustment value (for example, (−3, −4, −5)) applied to the reference gradation for each display device 10 after S24 in FIG. .

  Hereinafter, a method for calculating the adjustment value will be described. First, as shown in FIG. 29, the adjustment value calculation unit sets eight points P1 to P8 in the multi-display 1000 when each display device 10 is optimally arranged.

  Note that the points P1 to P8 use the reference area used in S24. Specifically, when it is assumed that the display devices 10a to 10d shown in FIGS. 26 and 29 are optimally arranged, the reference region F of the display device 10a is set as a point P1, and the reference region H of the display device 10a is set as a point P3. The reference region D of the display device 10b is set as a point P2, the reference region H of the display device 10b is set as a point P4, the reference region B of the display device 10c is set as a point P5, and the reference region F of the display device 10c is set as a point P7. The reference area B of the device 10d is set as a point P6, and the reference area D of the display device 10d is set as a point P8. That is, the adjustment value calculation unit is configured to set a pair of points facing each other across four boundaries between the display devices adjacent to each other.

Next, the adjustment value calculation unit uses the measurement data set corresponding to the mode of the mode number input in S23, and sets the representative value of the measurement value for each of the points P1 to P8 as the L ^* a ^* b ^* value. Ask. If the color selected from the M colors by the determination unit 600c in S24 is the same as the standard gradation, the representative value of each reference area corresponding to each point has already been obtained in S24. The value may be used.

The adjustment value calculation unit calculates a target value of L ^* value, a target value of a ^* value, and a target value of b ^* value. Target value of the L ^* value is the average of the ^{L *} value of point P1 to P8, the target value of the ^{a *} value is an average value of ^{a *} value of point P1 to P8, ^{b *} value of the target value Is an average value of b ^* values of points P1 to P8. That is, in the multi-display 1000 having the display device 10 of the four, the eight eligible points each of ^{L *} value, ^{a *} value, the ^{b *} value, the target value of ^{L *} value, the target value of the ^{a *} value, The target value of b ^* value is obtained one by one.

Subsequently, the adjustment value calculation unit obtains ΔL, Δa, and Δb for each of the points P1 to P8. ΔL is, L ^* value of the difference between the L ^* value of the target value and the target point, Δa is the difference between the a ^* value of the target value and the target point of a ^* value, Δb is, and the target value of the b ^* value The difference from the b ^* value of the target point. Further, the adjustment value calculation unit obtains ΔE for each of the points P1 to P8. ΔE can be obtained by, for example, the following Equation 6.
ΔE = {(ΔL) ² + (Δa) ² + (Δb) ² } ^1/2 formula 6
Next, the adjustment value calculation unit sets one target point for each of the display devices 10a to 10d. Specifically, as shown in FIG. 29, a pair of points is set for each of the display devices 10a to 10d. However, for each of the display devices 10a to 10d, the point having the larger ΔE among the pair of points. (The point with the maximum ΔE) is set as the target point.

  For example, as shown in FIG. 29, a pair of point P1 and point P3 is set on the display device 10a. If ΔE of point P1 is larger than ΔE of point P3, the adjustment value calculation unit The point P1 is set as the target point of the display device 10a. The adjustment value calculation unit also sets target points for each of the display devices 10b to 10d in the same manner as the display device 10a.

In the above example, two points are set for each display device, but three or more points may be set for each display device. In this case, three or more points are set per display device so that the points face each other across the boundary between adjacent display devices. Then, as in the above example, ΔE is obtained for each point (L ^* a ^* b ^* values (representative values) are obtained for each point, and the average value of all points is set for each of the L ^* a ^* b ^* values. And ΔE is obtained for each point using the target value). In each display device, a point having the maximum ΔE among the three or more points is extracted as a target point.

  Subsequently, the adjustment value calculation unit initially sets adjustment values (ΔR, ΔG, ΔB) for each of the display devices 10a to 10d. Specifically, the adjustment value calculation unit initially sets the adjustment value for each of the display devices 10a to 10d using Δa and Δb of the target points of the respective devices as follows.

When Δa> 0, a negative value of ΔR = adjustment coefficient A × (−1) is initially set so that R is in the direction of decreasing (red is suppressed).
When Δa <0, a negative value of ΔG = adjustment coefficient B × (−1) is initially set so that G decreases (green is suppressed).
In the case of Δb> 0, in the direction of decreasing R and G (suppressing yellow), ΔR = a negative value that is an adjustment coefficient C × (−1), ΔG = a negative value that is an adjustment coefficient C × (−1) Is initialized.
In the case of Δb <0, a negative value of ΔB = adjustment coefficient D × (−1) is initially set in the direction of decreasing B (suppressing blue).
The adjustment coefficients A, B, C, and D are positive numbers, and are set as, for example, A = 1, B = 1, C = 2, and D = 1. However, these values depend on the characteristics of the display device and may be set arbitrarily.
Specifically, when Δa> 0 and b> 0, ΔR = adjustment coefficient A × (−1) + adjustment coefficient C × (−1) = (− 1) × (adjustment coefficient A + adjustment coefficient C) ΔG = adjustment coefficient C × (−1), ΔB = 0. When Δa <0 and Δb> 0, ΔR = adjustment coefficient C × (−1), ΔG = (adjustment coefficient B + adjustment coefficient C) × (−1), and ΔB = 0. Further, when Δa> 0 and Δb <0, ΔR = adjustment coefficient A × (−1), ΔG = 0, ΔB = adjustment coefficient D × (−1). When Δa <0 and Δb <0, ΔR = 0, ΔG = adjustment coefficient B × (−1), and ΔB = adjustment coefficient D × (−1).

  Next, the adjustment value calculation unit obtains ΔL ′, Δa ′, and Δb ′ for each of the initially set ΔR, ΔG, and ΔB for each of the display devices 10a to 10d as follows.

  First, the adjustment value calculation unit accesses each of the display devices 10a to 10d and acquires reference data (see Embodiment 1 and FIG. 2) of each of the display devices 10a to 10d.

  Subsequently, the adjustment value calculation unit performs the following processing for each display device. First, the adjustment value calculation unit calculates ΔL ′, Δa ′, Δb corresponding to each of ΔR, ΔG, ΔB from the correspondence relationship between RGB values and XYZ values for five colors in the reference data shown in FIG. Ask for '.

For example, among the four colors of RGB values (240, 240, 240), (224, 240, 240), (240, 224, 240), (240, 240, 224), (240, 240, 240), For (224, 240, 240), the XYZ values are converted into L ^* a ^* b ^* values. Then, from ^{the L} * ^a * ^{b *} value of the RGB values ^{(224,240,240), L * a *} b * value by subtracting the difference between the (240,240,240) (ΔL', Δa', Δb' ) This difference is ΔL ′, Δa ′, Δb ′ corresponding to ΔR = −16 in the display device to be processed. Further, ΔL ′, Δa ′, Δb ′ corresponding to ΔR = −1 can be obtained by dividing ΔL ′, Δa ′, Δb ′ by 16.

  Similarly, ΔL ′, Δa ′, and Δb ′ corresponding to ΔG = −1 are obtained using XYZ values of RGB values (240, 224, 240) and (240, 240, 240). Further, ΔL ′, Δa ′, and Δb ′ corresponding to ΔB = −1 are obtained using the XYZ values of RGB values (240, 240, 224) and (240, 240, 240).

  The adjustment value calculation unit obtains the relationship between ΔL ′, Δa ′, and Δb ′ for each ΔR, ΔG, and ΔB in this way, and then uses this relationship to set each of the initially set ΔR, ΔG, and ΔB. ΔL ′, Δa ′, and Δb ′ are obtained. Then, the adjustment value calculation unit changes the values of A, B, C, and D until the absolute values of ΔL ′, Δa ′, and Δb ′ converge to a predetermined value or less for each of ΔR, ΔG, and ΔB, Repeat the resetting (resetting ΔR, ΔG, ΔB). The adjustment value calculation unit determines ΔR, ΔG, and ΔB when the values of ΔL ′, Δa ′, and Δb ′ converge below a predetermined value as adjustment values.

  When the adjustment value calculation unit obtains the adjustment value for each display device 10 as described above, the adjustment value calculation unit accesses each display device 10 and sets the adjustment value in each display device 10.

  Specifically, when the display device 10 receives the adjustment value from the adjustment value calculation unit in the arrangement determination device 600, the display device 10 stores the adjustment value in the storage unit 26 and performs video processing using the adjustment value. For example, it is assumed that the reference gradation is (255, 255, 255), and the R, G, B adjustment values of the upper left display device 10a of the multi-display 1000 are (-3, -4, -5). In this case, the video data processing unit 32 of the display device 10a calculates (252, 251 and 250) as the gradation value after adjustment value addition with respect to the reference gradation (255, 255, 255).

  Further, the video data processing unit 32 linearly interpolates between the gradation value after the adjustment value is added to the reference gradation (255) and the lowest gradation value 0 for each of the R, G, and B channels. The one-dimensional look-up table indicating the relationship between the input value (0 to reference gradation) and the output value (0 to gradation value after adjustment value addition) is stored in the storage unit 26.

  The video data processing unit 32 uses the one-dimensional look-up table as output gradation correction data at a later stage than the unevenness correction unit 36. That is, the video data processing unit 32 performs tone correction on the video data after the color unevenness correction by the unevenness correction unit 36 using the one-dimensional look-up table.

  As described above, by setting an adjustment value for fine adjustment of the output gradation for each display device, the gap between adjacent display devices can be suppressed after optimal placement, and the color of the entire multi-display is uniform. The property can be kept good.

  In addition, the arrangement determination apparatus 600 displays a UI as shown in FIG. 28 on the monitor, and inputs information, outputs an arrangement determination result, and outputs an adjustment value calculation result using this UI. Also good. 28, the operator enters the identification number, mode number, number of arrangements, and installation direction of each display device 10 and presses the execution button. This is the same as the UI of FIG.

  When the execution button is pressed, the result output unit 600d also displays a layout (reference numeral 450b) indicating the arrangement of the display device in the UI of FIG. Further, the result output unit 600d displays the correspondence relationship between the monitor ID, the reference gradation before adjustment, and the adjustment value (adjustment amount) in the UI of FIG. 28 (reference numeral 460). In this way, not only the optimal arrangement of each display device 10 but also the adjustment value set for each display device 10 can be easily notified to the operator.

  In the above example, the adjustment value is calculated with the reference gradation as (255, 255, 255). Therefore, the R, G, and B values can be adjusted only in the negative direction, and the negative adjustment value is used. For example, when the reference gradation is (240, 240, 240), in addition to the negative adjustment value obtained as described above, a positive adjustment value to be adjusted in the positive direction is also set. Calculate one of them and finalize it as the final adjustment value. Specifically, it is as follows.

  The adjustment value calculation unit calculates a negative adjustment value for each of the display devices 10a to 10d as in the example described above, and then calculates Δa and Δb of the target point of each device for each of the display devices 10a to 10d. Are used to initialize positive adjustment values (ΔR, ΔG, ΔB) as follows.

When Δa> 0, a positive value of ΔG = adjustment coefficient E is initially set so that G is increased (green is emphasized).
When Δa <0, a positive value of ΔR = adjustment coefficient F is initially set so that R is increased (red is emphasized).
When Δb> 0, a positive value of ΔB = adjustment coefficient G is initially set in the direction of increasing B (emphasizing blue).
When Δb <0, positive values such as ΔR = adjustment coefficient H and ΔG = adjustment coefficient H are initially set in the direction of increasing R and G (highlighting yellow).
The adjustment coefficients E, F, G, and H are positive numbers, and are set as, for example, E = 2, F = 1, G = 2, and H = 2. However, these values depend on the characteristics of the display device and may be set arbitrarily.
Specifically, when Δa> 0 and Δb> 0, ΔR = 0, ΔG = adjustment coefficient E, ΔB = adjustment coefficient G, and when Δa <0 and Δb> 0, ΔR = adjustment coefficient F, ΔG = 0, ΔB = adjustment coefficient G. Further, when Δa> 0 and Δb <0, ΔR = adjustment coefficient H, ΔG = adjustment coefficient E + adjustment coefficient H, ΔB = 0, and when Δa <0 and Δb <0, ΔR = adjustment coefficient F + adjustment coefficient H. , ΔG = adjustment coefficient H, ΔB = 0.

Next, the adjustment value calculation unit obtains ΔL ′, Δa ′, and Δb ′ for each of ΔR, ΔG, and ΔB that are initially set positive adjustment values for each of the display devices 10a to 10d. The method of obtaining is the same as in the case of a negative adjustment value. For example, from ^{the L} * ^a * ^{b *} value of the RGB values (240, 240, 240), (224,240,240) of the ^L * ^a * ^{b *} value by subtracting the difference (ΔL', Δa', Δb' ) As ΔL ′, Δa ′, Δb ′ corresponding to ΔR = + 16, and ΔL ′, Δa ′, Δb ′ are divided by 16 to obtain ΔL ′, Δa ′, Δb ′ corresponding to ΔR = + 1. Can be requested.

  Then, the adjustment value calculation unit calculates E, F, G, H until the absolute value of ΔL ′, Δa ′, Δb ′ converges to a predetermined value or less for each of positive adjustment values ΔR, ΔG, ΔB. Is changed, and resetting (resetting ΔR, ΔG, and ΔB) is repeated. The adjustment value calculation unit determines ΔR, ΔG, ΔB when the values of ΔL ′, Δa ′, Δb ′ converge below a predetermined value as positive adjustment values.

  Subsequently, the adjustment value calculating unit obtains ΔE obtained from ΔL ′, Δa ′, and Δb ′ of ΔR of the positive adjustment value, and ΔE obtained from ΔL ′, Δa ′, and Δb ′ of ΔR of the negative adjustment value. And the adjustment value (ΔR) corresponding to the smaller ΔE is determined as the final value. Similarly, final values for ΔG and ΔB are determined. As a result, ΔR, ΔG, and ΔB that are finally determined are not necessarily negative values, and may be positive values.

(Modification of Embodiment 4)
In the first embodiment, adjustment values for one set of reference gradations (255, 255, 255) are calculated. However, a plurality of reference gradations are set for each of R, G, and B channels (for example, (255 255, 255) (225, 225, 225), etc.), by obtaining the adjustment value for each reference gradation and performing spline interpolation using each reference gradation after the adjustment value is added, A look-up table may be created. In this case, the reference gradation may be designated by the user via the UI or the like.

  Moreover, although the multi-display which has arrange | positioned each display apparatus according to the determination result of the arrangement | positioning determination apparatus 600 of Embodiment 2-4 was used, according to a user's liking and use environment, the mode set initially is used. Sometimes you want to switch. For example, if the user changes the illumination brightness in an environment where a multi-display is installed, the user switches from the brightness unevenness suppression priority mode that has been used until now to the high brightness mode, or conversely the brightness decreases a little. There is a case where it is desired to switch from the high luminance mode to the luminance unevenness suppression priority mode in order to display with more uniformity.

  When the mode to be set is switched, it is possible to change the arrangement of the display devices constituting the multi-display, but changing the arrangement takes time, labor, and cost.

  For this reason, after switching the setting mode, the layout of each display device constituting the multi-display is not changed, and an adjustment value that suppresses variation among new display devices due to the setting mode switching (adjustment value of the fourth embodiment). May be calculated. Thereby, even when the setting mode is switched, there is an advantage that the deterioration of uniformity between the display devices can be reduced without changing the arrangement.

  Specifically, after switching the mode of each display device, the arrangement determining device 600 is connected to each display device 10. The arrangement determination device 600 reads a measurement data set from each display device 10.

  Thereafter, the arrangement determination apparatus 600 inputs a mode after switching and information indicating an existing layout by a user operation. The information indicating the existing layout may be information indicating a correspondence relationship between the identification number of the display device 10 and position information (coordinate values or the like) indicating the layout. Let the user enter this information.

  Subsequently, the arrangement determination apparatus 600 uses the method of the fourth embodiment to obtain an adjustment value corresponding to the mode after switching and the existing layout, and sets the adjustment value in each display apparatus 10.

  Even if the setting mode is changed by the above method, the layout of the display device that constitutes the multi-display is calculated and set using the measurement data stored in the display device alone. Even without changing, it is possible to perform display with as little variation as possible between display devices in the new setting mode.

  In the above example, the adjustment value is obtained when the setting mode is changed. However, when the multi-display is installed, it is used after appropriately arranging each display device by the user without determining the optimum arrangement. The mode to be set may be set, and then the adjustment value may be obtained by the procedure of this modification.

[Example of implementation by software]
Each unit 600a to 600d included in the control unit 25 and the arrangement determination apparatus 600 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or using a CPU (Central Processing Unit). It may be realized by software.

  In the latter case, each of the units 600a to 600d included in the control unit 25 and the arrangement determination apparatus 600 is a CPU that executes instructions of a program that is software that realizes each function, and the program and various data are read by a computer (or CPU). A ROM (Read Only Memory) or a storage device (these are referred to as “recording media”), a RAM (Random Access Memory) in which the program is expanded, and the like are provided. And the objective of this invention is achieved when a computer (or CPU) reads the said program from the said recording medium and runs it. As the recording medium, a “non-temporary tangible medium” such as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. The program may be supplied to the computer via an arbitrary transmission medium (such as a communication network or a broadcast wave) that can transmit the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

[Summary]
(Summary of Embodiment 1)
The video processing apparatus (control unit 25) according to aspect 1 of the present invention includes a switching unit (overall control unit 31) that can switch at least between the first mode and the second mode, which are image quality correction modes, in accordance with an input instruction. In either case of the first mode or the second mode, the pixel for the video data to be displayed on the display panel (display unit 14) using the color unevenness correction data obtained by executing the calibration process. A correction unit (unevenness correction unit 36) that performs color unevenness correction for each pixel, and in the second mode, the correction unit uniformly sets the gradation value of the video data to the lower gradation side for each pixel. The color unevenness correction is performed after the gradation value is suppressed to the lower gradation side than the first mode by performing the gradation restriction process to be shifted.

  In the configuration of the aspect 1 of the present invention, the gradation limiting process is performed according to the second mode in which the gradation unevenness correction is performed after the gradation limiting process for shifting the gradation value of the video data to the low gradation side is performed. Although the brightness of the entire image is lower than the case of performing color unevenness correction without performing the color unevenness correction by performing gradation limitation processing after suppressing the degree of shift as compared with the second mode. It has been found that the degree of pseudo luminance unevenness suppression accompanying unevenness suppression increases.

  Therefore, in aspect 1 of the present invention, in a case where there is a high necessity for performing high-luminance display (for example, a case where it is used as signage), although the degree of pseudo luminance unevenness suppression is suppressed by switching to the first mode, In cases where it is possible to display in a high luminance region and there is a high need to suppress luminance unevenness (for example, a case where it is used as one of display devices included in a multi-display), the luminance of the entire image is switched by switching to the second mode. However, the degree of suppression of pseudo luminance unevenness can be increased. In other words, high-brightness display can be realized in applications where there is a high need for high-brightness display, and brightness-unevenness suppression can be increased in applications where there is a high need to suppress luminance unevenness, even if the use of the display device changes. There is an effect that it is possible to realize video processing suitable for each application.

  According to the first aspect of the present invention, in the second mode, the color unevenness correction is performed after performing the gradation restriction process, thereby suppressing the color unevenness, and the pseudo brightness unevenness caused by the color unevenness suppression. It has the advantage of increasing the effect of mechanical suppression. Here, since the gradation limiting process uniformly applies the same correction to all pixels, it does not place an excessive burden on the computer. Thus, in the present invention, both color unevenness and luminance unevenness are effectively reduced while suppressing the burden on the computer as much as possible. On the other hand, Patent Document 1 (Japanese Patent Laid-Open No. 2013-97115) does not have the advantage of the present invention because it is not a configuration that performs color unevenness correction in the first place.

  In the video processing apparatus according to aspect 2 of the present invention, the correction unit performs the color unevenness correction without performing the gradation restriction process in the first mode. The video processing device according to aspect 3 of the present invention is the video processing apparatus according to aspect 2, wherein the switching unit is capable of switching to a first mode, a second mode, and a third mode in accordance with the input instruction. However, in the third mode, the color unevenness correction is performed after the gradation restriction process is performed with the degree of shift being suppressed as compared with the second mode.

  In the video processing device according to aspect 4 of the present invention, in the first mode, the color unevenness is performed in the first mode after the gradation limiting process is performed with the degree of shift being suppressed compared to the second mode. Make corrections. The video processing apparatus according to aspect 5 of the present invention is the video processing apparatus according to aspect 4, wherein the switching unit can be switched to a first mode, a second mode, and a third mode in accordance with the input instruction. In the third mode, the correction unit performs the gradation restriction process with the degree of shift being stronger than that in the first mode while suppressing the degree of shift as compared with the second mode, and then performing the color unevenness. Correction is applied.

  According to the video processing devices of aspects 3 and 5 of the present invention, it is not necessary to maintain the high luminance so as to be in the first mode, but in the second mode, the luminance may be insufficient, Although it is not necessary to suppress display unevenness as much as it has to be in the mode, in the case where display unevenness is noticeable in the first mode, by setting the third mode, video processing suitable for these cases is performed. There is an effect that it can be realized.

  In the video processing device according to aspect 6 of the present invention, the correction unit shares a color unevenness correction table in the first mode and the second mode. In the video processing device according to aspect 7 of the present invention, the correction unit shares a color unevenness correction table in the first mode, the second mode, and the third mode.

  According to the sixth and seventh aspects of the present invention, since the color unevenness correction table is shared in all modes, the storage capacity can be saved compared to a configuration in which an unevenness correction table is prepared for each mode. There is.

(Summary of Embodiments 2 to 4)
Aspect 8 of the present invention is an arrangement determination apparatus that determines the optimum arrangement of each display device in a multi-display, and each display apparatus has a plurality of modes with different degrees of unevenness correction, and the arrangement determination apparatus Indicates a mode selection unit that selects one of the plurality of modes according to a user's input operation, and the color of the test image displayed in each of the plurality of modes for each display device 10 Of the information stored in the storage unit (storage unit of the installation server) that stores the measurement values in advance, the mode selection unit selects the measurement value related to the mode selected by the mode selection unit 600b. A determination unit (arrangement determination unit 600c) that determines the optimal arrangement of each display device 10 in the display mode.

  According to the aspect 8 of the present invention, among the measurement values obtained by measuring the test images corrected in each of the plurality of modes, the measurement value of the mode specified by the user is used to optimize the mode specified by the user. Judgment is made. Therefore, it is possible to determine an optimum arrangement for a mode in actual use for a multi-display using a display device having a plurality of modes having different degrees of unevenness correction.

  The arrangement determination apparatus according to aspect 9 of the present invention is the arrangement determination apparatus according to aspect 8, wherein the plurality of modes include at least first and second modes, and the first and second modes are both obtained by executing a calibration process. In this mode, color unevenness correction is performed for each pixel of video data displayed on the display panel using color unevenness correction data. The second mode is a mode in which the video data is uniformly applied to each pixel. By performing the gradation limiting process for shifting the gradation value to the low luminance side, the color unevenness correction is performed after suppressing the gradation value to the low luminance side as compared with the first mode.

  In addition, the arrangement determination apparatus according to the tenth aspect of the present invention is the result output unit that causes the display unit to display information in which the identification information of each display device and the position information of each display device are associated with each other in the eighth or ninth aspect. It has. Thereby, the user can easily recognize the determination result of the optimum arrangement.

  The aspect determination device according to aspect 11 of the present invention corresponds to the predetermined reference gradation in (a) the mode selected by the mode selection unit for each display device constituting the multi-display in aspects 8 to 10. Calculating a color difference between a target value of the measured value when displaying a test image to be displayed and a common target value for each display device and the measured value when displaying a test image corresponding to the reference gradation (B) An adjustment value calculation unit that calculates an adjustment value to be set for the reference gradation in order to bring the measurement value when displaying the reference gradation test image close to the target value based on the color difference It is characterized by having.

  According to the aspect 11 of the present invention, if the output gradation is adjusted using the adjustment value for each display device, there is an advantage that a gap between adjacent display devices can be suppressed. In addition, although it is how to use an adjustment value, the following methods can be mentioned as an example. First, each adjustment value is set for each display device. Next, in each display device, for each color component, the reference gradation is adjusted using the adjustment value, and the input value is obtained by linear interpolation between the adjusted reference gradation and the lowest gradation (for example, 0). And a one-dimensional look-up table showing the relationship between the output value and the output value. Each display device performs output gradation correction after color unevenness correction using the one-dimensional look-up table.

  Aspect 11 of the present invention is an arrangement determination method for determining the optimum arrangement of each display device in a multi-display, and each display device has a plurality of modes with different degrees of unevenness correction, and each display device Measuring a measurement value indicating the color of the test image displayed on the display device in each of the plurality of modes, and among the measurement values obtained in the measurement step, the user among the plurality of modes. A determination step of determining an optimum arrangement of each display device in the designated mode with reference to a measurement value related to the designated mode.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be used for a display device or a multi-display system in which a plurality of display devices are arranged.

10 Display Device 14 Display Unit (Display Panel)
25 Control unit (video processing device)
26 Storage Unit 31 General Control Unit (Switching Unit)
35 Calibration processing unit 36 Unevenness correction unit (correction unit)
40 System Controller 50 Measuring Device 600 Arrangement Determination Device 600a Measurement Data Acquisition Unit 600b Mode Selection Unit 600c Determination Unit (Arrangement Determination Unit)
600d Result output unit 601 Installation server 1000 Multi display

Claims (10)

A switching unit capable of at least switching between the first mode and the second mode, which are image quality correction modes, in accordance with an input instruction;
In either case of the first mode or the second mode, the color unevenness correction for each pixel is performed on the video data of the video displayed on the display panel using the data for correcting color unevenness obtained by executing the calibration process. A correction unit for performing
In the second mode, the correction unit performs a gradation limiting process that uniformly shifts the gradation value of the video data to the low gradation side for each pixel, so that the gradation is higher than that in the first mode. An image processing apparatus that performs the color unevenness correction while suppressing a value to a low gradation side.   The video processing apparatus according to claim 1, wherein the correction unit performs the color unevenness correction without performing the gradation restriction process in the first mode. The switching unit can be switched to the first mode, the second mode, and the third mode according to the input instruction,
The video processing apparatus according to claim 2, wherein the correction unit performs the color unevenness correction in the third mode after performing the gradation restriction process while suppressing the degree of shift compared to the second mode.   2. The video processing device according to claim 1, wherein the correction unit performs the color unevenness correction in the first mode after performing the gradation limiting process while suppressing the degree of shift compared to the second mode. . The switching unit can be switched to the first mode, the second mode, and the third mode according to the input instruction,
In the third mode, the correction unit performs the gradation limiting process with the degree of shift being stronger than that in the first mode while suppressing the degree of shift as compared with the second mode, and then performing the tone restriction process. The video processing apparatus according to claim 4, wherein unevenness correction is performed.   The video processing apparatus according to claim 1, wherein the correction unit shares a color unevenness correction table in the first mode and the second mode.   The video processing apparatus according to claim 3, wherein the correction unit shares a color unevenness correction table in the first mode, the second mode, and the third mode.   A display device comprising: the video processing device according to claim 1; and the display panel.   A program for causing a computer to function as the video processing apparatus according to claim 1, wherein the program causes the computer to function as each unit.   A computer-readable recording medium on which the program according to claim 9 is recorded.