KR102812240B1 - Compensation Device for Compensating Brightness Deviation of LED Display and Driving Method Thereof - Google Patents

Abstract

The present invention relates to a correction device for correcting brightness deviation of an LED display and a method for driving the device. The correction device for correcting brightness deviation of an LED display according to an embodiment of the present invention may include: a storage unit for storing brightness value data corresponding to the grayscale of each pixel of a boundary surface related to a boundary portion between LED panels that are physically separated from each other and face each other among a plurality of LED panels constituting an LED display device; and a control unit for dividing a grayscale section into a plurality of sections using the stored brightness value data and a gamma value corresponding to the grayscale and generating different correction formulas for applying to each section, and generating correction data for correcting each pixel of the boundary surface of the boundary portion using the correction formulas of each section generated respectively, and outputting the correction data for use in the LED display device.

Description

{Compensation Device for Compensating Brightness Deviation of LED Display and Driving Method Thereof}

The present invention relates to a correction device for correcting brightness deviation of an LED display and a method for driving the device. For example, the present invention relates to a correction device for correcting brightness deviation of an LED display, which corrects brightness deviation at a boundary caused by physical interference between modules or cabinets after installing an electric signboard constituting an LED display, and a method for driving the device.

LED displays are usually made up of multiple boxes, each box is made up of multiple modules, and each module is made up of multiple small modules. When these modules are combined, the problem of excessively large gaps between modules and boxes in the combined LED display may occur. This causes the gap between pixels in the combined part to be larger than the standard gap, and black lines are visible at the combined part when the display is displayed. These black lines deteriorate the visual quality of the display, which negatively affects the user experience.

To solve this problem, conventionally, the correction coefficient of the pixel at the black line position (i.e., the pixel that needs correction) is calculated, and the pixel is corrected based on this. However, while the correction effect is good for high-brightness (i.e., high grayscale) pixels, the black line problem is still prominent for low-brightness (i.e., low grayscale) pixels. This is mainly because the brightness of the pixel is low at low brightness, so the gap between the pixels is more easily visible. Therefore, a new technical method to solve this problem is required.

Korean Patent Publication No. 10-1489285 (January 28, 2015) Korean Patent Publication No. 10-1741638 (May 24, 2017) Korean Patent Publication No. 10-0437810 (June 17, 2004) Korean Patent Publication No. 10-2008-0034590 (April 22, 2008)

The purpose of an embodiment of the present invention is to provide a correction device for correcting brightness deviation of an LED display, which corrects brightness deviation at a boundary caused by physical interference between modules or cabinets (or cabinets) after installing an electric signboard or the like constituting an LED display, and a method for operating the device.

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

A correction device for correcting brightness deviation of an LED display according to an embodiment of the present invention includes: a storage unit that stores brightness value data corresponding to the grayscale of each pixel of a boundary surface related to a boundary portion between LED panels that are physically separated and face each other from a plurality of LED panels constituting an LED display device; and a control unit that divides the grayscale section into a plurality of sections using the stored brightness value data and a gamma value corresponding to the grayscale and generates different correction formulas for applying to each section, and generates correction data for correcting each pixel of the boundary surface of the boundary portion using the correction formulas of each section generated, and outputs the correction data for use in the LED display device.

The above control unit can store and use an average brightness value corresponding to a grayscale value measured and collected during the calibration process for each LED panel during the production of the LED display device as the brightness value data.

The above control unit sets a first threshold value and a second threshold value for dividing the above sections, respectively, and then divides each section into a linear section and a nonlinear section based on the set first threshold value and the second threshold value, and can generate a correction formula based on the brightness value corresponding to the grayscale in each of the divided linear and nonlinear sections.

The above control unit calculates a corresponding gamma value (gamma) by inversely calculating the brightness value collected for each pixel of the above boundary surface through the above correction formula, determines whether the obtained gamma value is larger or smaller than a preset threshold value, and when the determination result is smaller, applies the gamma value obtained to the correction formula and substitutes it to calculate the calculated value as a final correction coefficient so that the calculated final correction coefficient is used as the correction data.

The above control unit sets a pixel range for applying a gradient centered on a boundary line of the boundary area by using grayscale values and brightness values of pixels surrounding a boundary of adjacent and facing LED panels, and changes the grayscale values of pixels in the set pixel range in stages according to preset conditions as the distance from the boundary line increases, and recalculates the brightness value of each pixel based on the changed grayscale values so that the brightness of each pixel is corrected with the recalculated brightness value.

The above control unit can provide data including a constant of the above correction formula, a modified correction coefficient, and a grayscale value applied to the above gradient as the above correction data to the control unit of the LED display device.

In addition, a method for driving a correction device for correcting brightness deviation of an LED display according to an embodiment of the present invention includes a step in which a storage unit stores brightness value data corresponding to a grayscale of each pixel of a boundary surface related to a boundary portion between LED panels that are physically separated and adjacent to each other in relation to a plurality of LED panels constituting an LED display device, and a step in which a control unit divides a section of the grayscale into a plurality of sections using the stored brightness value data and a gamma value corresponding to the grayscale, and generates different correction formulas for applying to each section, and generates correction data for correcting each pixel of the boundary surface of the boundary portion using the correction formulas of each section generated, and outputs the correction data for use in the LED display device.

The above-mentioned saving step can store and use the average brightness value corresponding to the grayscale value measured and collected during the calibration process for each LED panel during the production of the LED display device as the brightness value data.

The step of generating each of the above correction formulas comprises: setting a first threshold value and a second threshold value for dividing the above sections, and then dividing each section into a linear section and a nonlinear section based on the set first threshold value and second threshold value; and generating a correction formula based on the brightness value corresponding to the grayscale in the divided linear section and nonlinear section, respectively.

The outputting step may include a step of calculating the corresponding gamma value (gamma) by inversely calculating the brightness value collected for each pixel of the boundary surface through the correction formula, and a step of determining whether the obtained gamma value is larger or smaller than a preset threshold value, and when the determination result is smaller, applying the gamma value obtained to the correction formula and substituting the calculated value as a final correction coefficient so that the calculated final correction coefficient is used as the correction data.

The outputting step may include a step of setting a pixel range for applying a gradient centered on a boundary line of the boundary area by using grayscale values and brightness values of pixels surrounding a boundary of adjacent and facing LED panels, a step of gradually changing the grayscale values of pixels in the set pixel range according to preset conditions as the distance from the boundary line increases, and a step of recalculating the brightness value of each pixel based on the changed grayscale values so that the brightness of each pixel is corrected with the recalculated brightness value.

The outputting step may include a step of providing data including a constant of the correction formula, a modified correction coefficient, and a grayscale value applied to the gradient as the correction data to a control device of the LED display device.

According to an embodiment of the present invention, by dividing the grayscale range of each pixel at each boundary of an LED display into two or more sections, such as low brightness and high brightness, and differentially applying a coefficient corrected for each section by a correction formula generated based on a low brightness threshold value, a high brightness threshold value, a grayscale within each section, and a corresponding brightness value, it is possible to obtain an effect in which the brightness of each pixel is smoothly matched.

In addition, according to an embodiment of the present invention, by transmitting a modified correction coefficient to an LED display to correct the boundary pixels, the boundary brightness heterogeneity that physically occurs through the correction effect of the display can be improved in terms of quality.

The effects according to the present invention are not limited to those exemplified above, and further diverse effects are included in the present specification.

FIG. 1 is an exemplary diagram showing a correction system for correcting brightness deviation of an LED display according to an embodiment of the present invention.
Figure 2 is a photograph comparing the before and after border correction of the LED display device of Figure 1.
Figure 3 is a flow chart showing the driving process of the brightness deviation correction device of Figure 1.
Figures 4a to 4c are drawings for explaining the brightness deviation correction process of Figure 3.
Figure 5 is a block diagram illustrating a detailed structure of the brightness deviation correction device of Figure 1.
FIG. 6 is a flowchart showing the driving process of a correction device for correcting brightness deviation of an LED display according to an embodiment of the present invention.

The present invention is not limited to the embodiments described below, but can be implemented in various different forms, and the present embodiments are merely illustrative of the contents of the present invention, and are provided to inform those skilled in the art of the invention in detail of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

The embodiments described herein will be described with reference to cross-sectional and/or plan views, which are ideal examples of the present invention. In the drawings, the illustrated regions are represented for effective explanation of the technical contents. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of element regions and are not intended to limit the scope of the invention. Although the terms first, second, third, etc. have been used to describe various components in various embodiments of the present specification, these components should not be limited by these terms. These terms are only used to distinguish one component from another. The embodiments described and illustrated herein also include complementary embodiments thereof.

The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless the context clearly dictates otherwise. The terms "comprises" and/or "comprising" as used herein do not exclude the presence or addition of one or more other components, steps, operations, and/or elements to the mentioned components, steps, operations, and/or elements.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with a meaning that can be commonly understood by a person of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries shall not be ideally or excessively interpreted unless explicitly specifically defined.

Hereinafter, the concept of the present invention and embodiments thereof will be described in detail with reference to the drawings.

FIG. 1 is an exemplary diagram showing a correction system for correcting brightness deviation of an LED display according to an embodiment of the present invention, and FIG. 2 is a photograph comparing the LED display device of FIG. 1 before and after boundary correction.

As illustrated in FIG. 1, a correction system for correcting brightness deviation of an LED display according to an embodiment of the present invention (hereinafter, brightness deviation correction system) includes part or all of an LED display device (100) and a brightness deviation correction device (110).

Here, “including some or all” means that some components, such as a brightness deviation correction device (110), may be integrated into the LED display device (100), and is described as including all in order to help sufficient understanding of the invention.

The LED display device (or LED image display device) (100) may refer to an image display device having a panel that implements an image using a self-luminous element such as an (O)LED. Of course, in the embodiment of the present invention, a display device having an LED backlight and using an LCD panel for implementing an image may be used, so it will not be particularly limited to any one form. Above all, the LED display device (100) according to the embodiment of the present invention is an LED display device such as an electric signboard installed outdoors, and can be distinguished from an image display device that is generally installed in a home, that is, a type in which an (O)LED panel implementing an image is manufactured in a large size. This is because the manufacturing process may be somewhat different. The LED display device (100) according to the embodiment of the present invention is an electric signboard installed outdoors that implements an advertising image, and after arranging a plurality of M × N LED panels (e.g., modules or cabinets storing the corresponding modules) on a lower cover in the form of a matrix, the implementation of an image can be reproduced by controlling a data driver through a control unit such as a timing controller (T-CON). Of course, multiple LED panels, or more precisely, LED modules that make up the panel, can be configured by packaging red (R), green (G), and blue (B) light-emitting elements for each pixel that makes up the pixels on the board. In other words, elements in which red (R), green (G), and blue (B) light-emitting elements are packaged can be mounted on the board.

The LED display device (100) according to the embodiment of the present invention can perform an operation to correct brightness deviation on the screen that may occur for various reasons when implementing an image on a plurality of LED modules (or LED modules housed in each cabinet) configured in a row or matrix form. Or, it can receive correction data related to the correction and implement an image accordingly. Of course, it can also be viewed as a problem that occurs due to unevenness of light caused by LED light-emitting elements because there is no light-emitting element at the boundary area facing each other between adjacent LED modules or because the gap between them is too wide. To this end, the LED display device (100) can perform a brightness deviation correction operation by externally connecting a separate device for correcting brightness deviation, but it is also possible to integrate a brightness deviation correction device (110) into the LED display device (100), and thus the embodiment of the present invention will not be particularly limited to any one form. For example, since an LED display device (100) such as a TV can control an image implemented on a screen by connecting a set-top box (STB), the brightness deviation correction device (110) according to an embodiment of the present invention can be installed in the set-top box and operate. Since various configurations are possible, the embodiment of the present invention will not be particularly limited to being connected to the outside and operating. The brightness deviation correction device (110) can be a part of a device such as an LED display device (100) or a set-top box, but can also be a recording medium configured in the form of an IC chip installed inside, and thus, in the case of such a device, it can be named a 'computing device' for the convenience of explanation.

The image implementation method of the LED display device (100) is not much different from the image implementation method that has already been known, but for example, if the brightness deviation correction device (110) is installed in a set-top box, the LED display device (100) may request the implementation of an advertising image to the LED display device (100) in order for the LED display device (100) to operate as a display board. In order to implement a single unit video frame image, voltages of red (R), green (G), and blue (B) for expressing gray levels are applied to LED light-emitting elements corresponding to the first scan line to implement a line image corresponding to one scan line, and then the pixel voltage of the corresponding data is held, and a line image corresponding to the scan line is implemented in the second scan line, thereby implementing an image corresponding to the video frame of the unit screen. Of course, the image implementation method is not the scan line method, but a method of implementing an image by dividing the screen into multiple areas can be used. Each data driver is responsible for implementing an image in each divided area. In fact, since the LED display device (100) implements 30 to 120 video frames per second on the screen, even if the area is divided to implement the image, general users may not be able to detect the change in the image. However, it can be seen that the LED display device (100) according to the embodiment of the present invention implements pixel values in which the brightness deviation that previously occurred in the LED display device (100) is improved upon according to the request of the set-top box or the brightness deviation correction device (110) of FIG. 1. In conclusion, the LED display device (100) according to the embodiment of the present invention can operate as at least one of the correction devices for correcting the brightness deviation of the LED display.

The brightness deviation correction device (110) may also operate as at least one of the correction devices for correcting the brightness deviation of the LED display according to the embodiment of the present invention, and as mentioned above, may be installed and operated inside the LED display device (100), or may be installed and operated inside the set-top box connected externally to the LED display device (100), or may be installed and operated inside the set-top box, or may be connected externally to the set-top box, and may be provided and operated in various forms. For example, the brightness deviation correction device (110) may have a slightly different correction value for correcting the brightness deviation depending on the characteristics of the LED display device (100) used as an electric signboard, etc. In other words, if the brightness deviation correction of a 42-inch LED display device (100) and a 49-inch LED display device (100) is performed in the same manner, the brightness deviation may occur more. Therefore, it is preferable that the brightness deviation correction device (110) according to the embodiment of the present invention reflects the characteristics, such as the specifications, of the LED display device (100) to which correction is currently being made, and corrects the brightness deviation accordingly. The above simply assumes the size of the panel, but since the characteristics of the panel may differ depending on the manufacturer that manufactures the LED display device (100), it is preferable to reflect such characteristics as well. FIG. 2 shows a comparison of the brightness deviation of the boundary surface (or boundary line) (A, A') on the screen of the LED display device (100) before and after correction, respectively.

The brightness deviation compensation device (1110) according to an embodiment of the present invention can perform an operation for compensating for a boundary brightness deviation that occurs due to the influence of physical interference between modules or cabinets after installing an electric signboard, for example. That is, a program implementing the corresponding operation can be executed. This method collects the brightness value of each pixel of the boundary, modifies the existing compensation coefficient, and when the same gray scale value is applied, the final brightness can be differentially applied, and includes a method of transmitting the modified compensation coefficient to the LED display device (100) to match the brightness of the pixels of the boundary line. More specifically, the gray scale range of each pixel of the boundary line is divided into two or more sections, such as low brightness and high brightness, and a compensation formula generated based on a low brightness threshold value, a high brightness threshold value, a gray scale within each section, and a corresponding brightness value is differentially applied to each section, thereby smoothly matching the brightness of each pixel. The modified compensation coefficient is transmitted to the LED display to compensate the boundary pixels. In the embodiment of the present invention, the low brightness or high brightness section can be named in various ways, such as a straight section, a curved section, a linear section, or a nonlinear section. It can be seen that the method and device according to the embodiment of the present invention improve the boundary brightness heterogeneity that physically occurs through the compensation effect of the display in terms of quality.

In addition to the above, the LED display device (100) and brightness deviation correction device (110) of Fig. 1 can perform various operations, and since the related contents will be continuously dealt with later, the detailed contents will be replaced with those contents.

FIG. 3 is a flow chart showing the driving process of the brightness deviation correction device of FIG. 1, and FIGS. 4a to 4c are drawings for explaining the brightness deviation correction process of FIG. 3.

For convenience of explanation, referring to FIGS. 3 to 4C together with FIG. 1, the brightness deviation compensation device (110) of FIG. 1 according to the embodiment of the present invention can perform operations of data collection and generation of a grayscale-brightness nonlinear graph (S300). More specifically, the brightness deviation compensation device (110) of FIG. 1 according to the embodiment of the present invention can perform operations of setting a grayscale value, collecting a brightness value, and generating a grayscale-brightness nonlinear graph at step S300. To set the grayscale value, the LED grayscale range is set based on an 8-bit grayscale for each LED cabinet, and here, the grayscale value (or gradation value) can be configured in 256 steps from 0 to 255. With respect to brightness value collection, the brightness value of each cabinet is measured during the calibration process during LED production, and an average brightness value corresponding to the collected grayscale value is stored, so that this value can be utilized. Furthermore, with regard to generating a grayscale-brightness nonlinear graph, a nonlinear graph can be generated based on the collected grayscale and brightness values. The horizontal axis can be a grayscale value (0 to 255), and the vertical axis can be a brightness value. The generated graph can be used to visualize the nonlinear relationship between grayscale and brightness and to be used for correction. Of course, the embodiment of the present invention will not be specifically limited to graph generation. It is sufficient to programmatically know the correlation between the grayscale value (0 to 255) and the brightness value.

In addition, the brightness deviation correction device (110) can perform grayscale section division and linearity judgment operations (S310). More specifically, the brightness deviation correction device (110) divides grayscale sections, determines linearity of each section, and determines a correction method according to the linearity judgment results. As an example of general section division, grayscale 0 to 89 can be divided into a low brightness section, grayscale 90 to 191 can be divided into a medium brightness section, and grayscale 192 to 255 can be divided into a high brightness section. The criteria for dividing the sections can be determined according to the point where the rate of change in brightness changes in the grayscale-brightness nonlinear graph or information requiring correction. In addition, there can be various ways to judge linearity of each section, but grayscale and brightness values can be organized into an array in each section. Here, a method of evaluating linearity by calculating the Pearson Correlation Coefficient can be an example. The calculation method calculates the Pearson correlation coefficient between the grayscale array and the brightness value array, and the judgment criterion is that in the embodiment of the present invention, if the correlation coefficient is 0.7 or higher, it is determined that there is linearity and straight-line correction can be applied, and if the correlation coefficient is less than 0.7, it is determined that the nonlinearity is large and curve correction can be applied. Finally, with regard to the determination of the correction method according to the linearity judgment result, the low brightness section has a low linearity with a correlation coefficient of 0.65, so curve correction is applied, the medium brightness section has a high linearity with a correlation coefficient of 0.85, so straight-line correction is applied, and the high brightness section has a high linearity with a correlation coefficient of 0.9, so straight-line correction can be applied. Here, each section may also be named the first section to the third section.

Furthermore, the brightness deviation correction device (110) according to the embodiment of the present invention can derive a correction formula for each section (S320). In this S320 step, the operation can be divided into a straight-line correction formula derivation operation (e.g., a section with high linearity) and a curve correction formula derivation operation (e.g., a section with low linearity). First, the linear formula related to the straight-line correction formula derivation can be expressed as <Relational Expression 1>.

[Relationship 1]

Linear formula F(x) = A + B × x

(Here, x is the grayscale value, F(x) is the brightness value, and A and B are constants (calculation targets))

In relation to the derivation of the straight-line correction formula, data selection and calculation of constants A and B can be performed as follows. First, data selection uses the minimum and maximum grayscale values of the corresponding interval and the corresponding brightness values. For example, the case of the medium brightness interval (90 to 191) can be expressed as in <Relationship 2>.

[Relationship 2]

Threshold_low = 90, Weight_low = F(90)

Threshold_high = 191, Weight_high = F(191)

The calculation of constants A and B can be done by substituting the threshold value and brightness value into the linear formula to generate two equations. These can be expressed as in <Relationship 3>, respectively.

[Relationship 3]

A + B × Threshold_low = Weight_low

A + B × Threshold_high = Weight_high

By solving the simultaneous equations, we can calculate A and B respectively.

Of course, the above operations can be calculated through the operation algorithm applied to the program, and since these operation formulas are applied to the program algorithm in the future, further explanation will be omitted.

The derivation of the curve (or nonlinear) correction formula can be expressed as in <Relationship 4>.

[Relationship 4]

Curve formula F(x) = A + B × x + C × x ²

(Here, A, B, C are constants (subjects of calculation))

In the process of deriving the curve correction formula, data selection selects three or more data points (grayscale-brightness pairs) within the interval. For example, in the low-brightness interval (0 to 89), grayscale values 0, 45, and 89 and their corresponding brightness values can be selected.

Calculation of constants A, B, and C is done by substituting selected data points into the curve formula to form three equations, and solving the simultaneous equations to calculate A, B, and C.

To smooth the transition between intervals, the compensation curve can be smoothed using Bezier curves or B-splines, and continuity conditions can be applied to adjust the brightness values and slopes (i.e., derivatives) of adjacent intervals to match.

The brightness deviation compensation device (110) according to the embodiment of the present invention can perform a correction coefficient modification operation of a boundary pixel after step S320 (S330). In step S330, detailed operations such as setting a low brightness range, checking the grayscale of the boundary pixel, obtaining a gamma value, comparing the gamma value with a threshold value, determining a weighting coefficient, modifying the correction coefficient, and applying the modified correction coefficient can be performed. When setting a low brightness range, a grayscale value of 0 to 89 is set as the low brightness range. Then, the grayscale of the boundary pixel can be checked to determine whether the boundary pixel is within the low brightness range. In relation to obtaining a gamma value, a gamma table can be referenced to obtain a gamma value corresponding to the grayscale of the boundary pixel. In relation to comparing a gamma value with a threshold value, a comparison can be made with a preset gamma threshold value, and the gamma threshold can be set for each color (e.g., red, green, blue). For example, it can be set in the form of R_threshold, G_threshold, B_threshold. Use a threshold value corresponding to the color of the border pixels.

The weight coefficient peak sets the weight coefficient to 1 when the gamma value exceeds the threshold, and uses the correction formula for the corresponding section as the correction formula when the gamma value is below the threshold. Use the formula for the corresponding section among the curve correction formula or the straight line correction formula. The gamma value of the boundary pixel is substituted into the formula to calculate the gamma value (F). For normalization, the weight coefficient can be obtained by dividing by the maximum brightness value, etc.

In the correction factor modification process, the modified correction factor can be calculated by multiplying the original correction factor by a weighting factor. This can be expressed as in <Relationship 5>.

[Relationship 5]

Modified correction factor = original correction factor × weight factor

Finally, a process of applying the modified correction factor can be performed. The modified correction factor can be transmitted to the LED display to correct the border pixels.

In addition, the threshold value according to the embodiment of the present invention may mean a low brightness threshold value (minimum value) and a high brightness threshold value (maximum value) in each grayscale section. In addition, although the gamma table and the threshold value are basically preset in the system, the gamma table is determined through precise calibration, so it is difficult to change it arbitrarily. Of course, the embodiment of the present invention does not change it arbitrarily, but it is not particularly limited to that. For example, it may be possible to select and use a specific gamma table according to display usage or characteristics in a state where multiple gamma tables are stored in advance. Furthermore, the threshold value can be changed as needed by the user in the display settings, and a different threshold value can be set for each RGB color.

In addition, the brightness deviation compensation device (110) of FIG. 1 performs a gradient compensation operation of pixels around the boundary line (S340). For the operation of step S340, operations such as collecting brightness data of pixels around the boundary line, setting a gradient compensation range, gradual adjustment of grayscale values, calculating grayscale values, recalculating brightness values, and smooth connection of brightness changes can be performed in detail. With respect to collecting brightness data of pixels around the boundary line, grayscale values and brightness values of pixels around the boundary line of both modules (e.g., modules that are physically separated and facing each other) can be collected based on the boundary line of the LED display. With respect to setting a gradient compensation range, a pixel range to which a gradient is applied can be set centered on the boundary line. For example, a range of 5 pixels on both sides from the boundary line can be specified. For gradual adjustment of grayscale values, the grayscale values of pixels can be gradually changed as they get farther from the boundary line. For example, on the A module side, the pixel order and grayscale values from the boundary can be, for example, Pixel 1: grayscale value 100, Pixel 2: grayscale value 105, Pixel 3: grayscale value 110, Pixel 4: grayscale value 115, etc., but on the B module side, the pixel order and grayscale values from the boundary can be, for example, Pixel 1: grayscale value 115, Pixel 2: grayscale value 110, Pixel 3: grayscale value 105, Pixel 4: grayscale value 100, etc.

Looking at the adjustment principle related to the adjustment calculation of grayscale values, the brightness deviation correction device (110) according to the embodiment of the present invention can calculate grayscale values using linear interpolation. The adjusted grayscale value G can be expressed as in <Relational Expression 6>.

[Relationship 6]

Here, Gstart represents the starting grayscale value (e.g., the grayscale value of the border pixel), Gend represents the ending grayscale value (e.g., the normal grayscale value inside the module), d represents the distance to the current pixel (e.g., the number of pixels), and D represents the entire gradient range (e.g., the total number of pixels).

Brightness recalculation recalculates the brightness value of each pixel based on the adjusted grayscale value, and the brightness value can be calculated using the existing grayscale-brightness correction formula.

Finally, a final correction is made so that the brightness change at the boundary is smooth through a smooth connection process of brightness change. The brightness deviation correction device (110) can perform this operation.

The brightness deviation correction device (110) according to the embodiment of the present invention can perform the final correction and application operation (S350). The operation can include detailed operations such as transmission of correction data to the FPGA or receiving card, correction processing, correction result confirmation and additional adjustment, and correction data storage and maintenance. In relation to transmission of correction data to the FPGA or receiving card, constants (A, B, C, etc.) of the correction formula, modified correction coefficients, and grayscale values applied with gradient can be transmitted to the control device of the LED display (e.g., FPGA, etc.). In relation to performing the correction processing, the control device of the LED display can correct pixel data in real time based on the received data, and adjust the brightness of the border and surrounding pixels to solve the border problem. In relation to correction result confirmation and additional adjustment, the display screen after correction is inspected (e.g., visual inspection, etc.) to check the correction effect, check whether the black line of the border is removed and whether the brightness change is smoothly connected, and if necessary, re-calibration can be performed by adjusting the parameters. In addition, the gradient range, grayscale change width, etc. can be adjusted. In relation to the storage and maintenance of correction data, the final correction data can be stored and utilized for subsequent maintenance. Recalibration can be performed according to changes or aging of the display environment. For example, if at least one of the LED display device (100) and the brightness deviation correction device (110) requires recalibration due to changes or aging of the display environment during the execution of step S350, it is entirely possible to request recalibration by presenting a pop-up window on the screen. Of course, it is entirely possible to precisely determine changes or aging of the display environment by applying an artificial intelligence (AI) program during this process.

FIG. 4a is a drawing for explaining high-brightness sections and low-brightness sections on a screen by a display panel, for example, a cabinet. X represents a gamma value corresponding to a grayscale value (0 to 255). For example, each color can express a grayscale, that is, the brightness (or brightness) is determined according to the grayscale value. For example, in the case of red (R), if the grayscale value is 0, it can be expressed the lightest (or brightest), and if it is 255, it can be expressed the darkest (or darkest). Of course, the opposite can also be true. The threshold value can be arbitrarily set by a technician, so no separate restrictions are imposed. As mentioned above, 0 to 89 is a low-brightness section, and the low-brightness threshold value can be 90. On the other hand, 199 to 255 is a high-brightness section, and the high-brightness threshold value can be 198. Figure 4b shows an example of a gamma table, and the gamma value of a boundary pixel is a gamma value obtained by looking up the grayscale value of the pixel in the gamma table.

Fig. 4c shows a graph for explaining the correction coefficient. The formula for the brightness correction coefficient (= weight coefficient) has been examined previously by dividing it into linear and nonlinear sections, and can be summarized as linear section: F(x) = A + B × x, and nonlinear section: F(x) = (A + B × x) + C × x ^2. A is the correction coefficient for the brightness to a constant at the start of the section, and B is a constant for adjusting the change rate of the section and represents the slope. Δy/Δx can be expressed as the value obtained by dividing the y-axis displacement by the x-axis displacement. Since the formulas for obtaining the constants A and B can be interpreted as a solution to a general first-order or second-order equation, a specific interpretation will be omitted.

Let's briefly look at the correction method according to the embodiment of the present invention again. After the threshold value is set, a correction formula is obtained based on the grayscale of each section and the corresponding brightness value. Constants A and B can be obtained through the correction formula according to each threshold value. The collected brightness value of the boundary pixel can be inversely calculated through the correction formula to obtain the corresponding gamma value, and it can be determined whether the gamma value at this time is greater than or less than the preset threshold value. If the gamma value exceeds the threshold value, the weight of the boundary pixel is set to 1, which means that it does not change. If it does not exceed the threshold value, the correction formula corresponding to the grayscale of the boundary pixel is applied, the gamma value is substituted, and the calculated value is used as the final correction coefficient. Since each pixel applies the correction coefficient differentially through the correction formula, even if the same gamma value is input, the amount of brightness displacement is different, so the consistency of the same brightness can be secured. This can be considered the main core operation of the brightness deviation correction device (110) of FIG. 1 according to the embodiment of the present invention.

Let us look at each step examined in Figure 3 in more detail through examples.

The brightness deviation correction device (110) of FIG. 1 according to an embodiment of the present invention can collect data, set a curve correction formula, and configure a simultaneous equation in the case of deriving a curve correction formula (low brightness range: 0 to 89). For data collection, grayscale and brightness values are measured, and several representative grayscale values and their corresponding brightness values are measured in the low brightness range. This can be expressed as in <Table 1>.

Data point Grayscale value(x) Measured brightness value (F(x)) Point 1 0 0 Dot 2 45 10 Dot 3 89 25

The curve correction formula can be set as follows. To correct the nonlinearity of the low-brightness section, the second-order curve formula F(x) = A + B x + C x ² can be used.

The simultaneous equations construction creates three equations by substituting the measured data points into the formula. Point 1 (x = 0, F(x) = 0): 0 = A + B 0 + C 0 ² → A = 0, Point 2 (x = 45, F(x) = 10): 10 = A + B 45 + C 45 ² , Point 3 (x = 80, F(x) = 25): 25 = A + B 89 + C 89 ² .

Calculating constants A, B, and C Since we already know that A = 0 (Step 1), we use equations 2 and 3 to calculate B and C (Step 2). In the above equation 2 means 10 = A + B 45 + C 45 ² , and equation 3 means 25 = A + B 89 + C 89 ² . Then, we solve the two equations simultaneously to find B and C (Step 3). If we rearrange equation 2, we get 10 = 45B + 2025C. If we rearrange equation 3, we get 25 = 89B + 7021C. We subtract equation 2 from the rearranged equation 3 to find the relationship between B and C. This can be expressed as <Relationship 7>.

[Relationship 7]

(25 - 10) = (89B - 45B) + (7921C - 2025C)

15 = 44B + 5896C

Based on <Relationship 7>, since there is one equation for two variables, additional data is needed. In reality, you may need to use more data points or determine B and C through certain assumptions. Here, you can improve accuracy by using additional data points. Additional data points can be expressed as in <Table 2>.

data point Grayscale value(x) Measured brightness value (F(x)) Point 4 30 5

Additionally, a new equation 4 can be obtained: 5 = B·39 + C·30 ² .

Now, we use equations (1), (2), and (4) to solve for B and C. However, since there are two variables, three equations are sufficient.

Therefore, B and C are calculated using equations (1) and (4) (Step 4).

Since equation (1) is 10 = 45B + 2025C and equation (4) is 5 = 30B + 900C, we can find the relationship between B and C by subtracting (4) from equation (1). This can be expressed as <Relationship Equation 8>.

[Relationship 8]

(10 - 5) = (45B - 30B) + (2025C - 900C)

5 = 15B + 1125C

5 = 15B + 1125C can be defined as equation (5).

Now we can solve for B and C using equation (5) and equation (3) obtained previously. Equation (3) gives 15 = 44B + 5896C.

To solve both equations simultaneously, divide equation (5) by 3 (Step 5). This can be 5/3 = 5B + 375C. This is defined as equation (5').

Now we use equations (3) and (5').

Multiply equation (5'). This is to adjust the coefficient of 5B to 44B. This can be expressed as <Relationship 9>.

[Relationship 9]

Now, subtract equations (3) and (5'') to obtain C. This can be expressed as <Relationship 10>.

[Relationship 10]

Based on <Relationship 10>, C can be obtained. Now, equation (5') is substituted to obtain B. This can be expressed as <Relationship 11>.

[Relationship 11]

Therefore, A = 0, , This could be it.

The curve correction formula can be completed, which can be expressed as <Relationship 12>.

[Relationship 12]

Meanwhile, the predicted brightness value for grayscale value 60 can be calculated to verify the correction formula. This can be expressed as <Relationship 13>.

[Relationship 13]

The accuracy of the correction formula can be verified by comparing it with the actual measured brightness values.

Next, the process of deriving a straight-line correction formula (medium brightness and high brightness sections) of the brightness deviation correction device (110) of FIG. 1 according to an embodiment of the present invention will be examined in detail.

For example, data collection can be performed to derive a straight-line correction formula for the mid-luminosity range of grayscale 90 to 191. Representative grayscale values and their corresponding brightness values can be measured in the mid-luminosity range. This can be expressed as in <Table 3>.

data point Grayscale value(x) Measured brightness value (F(x)) Point 1 90 30 Dot 2 191 80

Then, a linear correction formula is established, and the linear formula F(x) = A + B x for the intermediate brightness interval with linearity can be used.

To calculate constants A and B, we substitute two data points into the formula to create two equations. That is, we can obtain. Point 1 (x = 90, F (x) = 30) can be equation (1) 30 = A + B 90, and point 2 (x = 191, F (x) = 80) can be equation (2) 80 = A + B 191.

B can be obtained by using the difference between equations (1) and (2), which can be expressed as <Relationship 14>.

[Relationship 14]

Substitute the value of B into equation (1) to obtain A. This can be expressed as <Relationship 15>.

[Relationship 15]

The linear correction formula can be completed as in <Relationship Equation 16>.

[Relationship 16]

Next, the correction formula can be verified, and in the process, the predicted brightness value for the grayscale value 140 can be calculated. This can be expressed as <Relationship 17>.

[Relationship 17]

The accuracy of the correction formula can be verified by comparing it with the actual measured brightness values.

The process for the high brightness range of grayscale 192 to 255 is not much different from that for the medium brightness range.

For example, for data collection, representative grayscale values and corresponding brightness values can be measured in a high-brightness range. This can be represented as in <Table 4>.

Data point Grayscale value(x) Measured brightness value (F(x)) Point 1 192 85 Dot 2 255 100

Then, a linear correction formula F(x) = A + B x can be established.

To calculate constants A and B, point 1 (x = 192, F (x) = 85) can obtain equation (1) 85 = A + B 192, and point 2 (x = 255, F (x) = 100) can obtain equation (2) 100 = A + B 255, respectively.

B can be obtained by using the difference between equations (1) and (2), which can be expressed as <Relationship 18>.

[Relationship 18]

By substituting the value of B into equation (1), A can be obtained. This can be expressed as <Relationship 19>.

[Relationship 19]

Then, the linear correction formula can be completed as in <Relationship Equation 20>.

[Relationship 20]

To verify the correction formula, the predicted brightness value for the grayscale value 220 can be calculated. This can be expressed as <Relationship 21>.

[Relationship 21]

The accuracy of the correction formula can be verified by comparing it with the actual measured brightness values.

The brightness deviation compensation device (110) according to the embodiment of the present invention should be adjusted so that the brightness value and the slope are smoothly connected at the boundary point where the compensation formula for each section is applied in order to ensure continuity between sections. To this end, the constant of the compensation formula can be finely adjusted or an interpolation technique can be used. In addition, in terms of actual data utilization, the above example is virtual data to help understanding. In actual application, more data points can be collected and the compensation formula can be derived through accurate measurement. In relation to the application of the compensation formula, the derived compensation formula can be applied to the control device of the LED display (e.g., FPGA, etc.) to correct the grayscale value in real time.

Next, we will examine in more detail the determination of the weight coefficient of the brightness deviation correction device (110) of FIG. 1 according to an embodiment of the present invention. This may be related to step S330 of FIG. 3.

The final correction coefficient for weight coefficient modification can be set as in <Relationship 22>.

[Relationship 22]

Weight coefficient modificationFinal correction factor = Original correction factor × Modified weight

The existing correction factor refers to the correction value that is initially set or used previously. For example, if the threshold is 1.0, the gamma value is 0.8, and the existing correction factor is 1.0, then A = 0.5, B = 0.2, and C = 0.001. Since the gamma value G = 0.8G = 0.8 is smaller than the threshold value 1.0, the correction factor can be modified. The weight (W) can be expressed as in <Relationship 23.

[Relationship 23]

W = F(threshold) / F(G)

Based on <Relationship 23>, when the brightness value F(threshold) at the threshold is 0.701 and the brightness value F(G) at the gamma value is 0.66064, it can be expressed as <Relationship 24>.

[Relationship 24]

The final correction factor is 1.0 × 1.061, which is 1.0614. This can be expressed as <Relationship 25>.

[Relationship 25]

The following is an example of gradation correction of the brightness deviation correction device (110) of Fig. 1. This may be related to step S340 of Fig. 3.

The gradient correction formula has already been examined through <Relationship 6>.

Example conditions on the A module side and the B module side, which have a boundary surface or boundary line between them, can be given as follows.

On the A module side, Gstart can be 100 (border pixels), Gend can be 120 (normal grayscale value inside the module), D can be 4 (4 pixels from the border), and on the B module side, Gstart can be 120, Gend can be 100, and D can be 4.

At this time, the grayscale value according to the pixel distance d from the boundary line on the A module side can be calculated and organized as in <Relational Expression 26>.

[Relationship 26]

As a result of the calculation, Pixel 1 can be 100, Pixel 2 can be 105, Pixel 3 can be 110, Pixel 4 can be 115, and Pixel 5 can be 120.

On the other hand, if we calculate the grayscale value according to the pixel distance d from the boundary line on the B module side, we can organize it as in <Relationship Equation 27>.

[Relationship 27]

As a result of the calculation, Pixel 1 can be 120, Pixel 2 can be 115, Pixel 3 can be 110, Pixel 4 can be 105, and Pixel 5 can be 100.

The results from module A and module B can be summarized again as in <Table 5> and <Table 6>.

Pixel number Distance d Grayscale value G pixel 1 0 100 pixel 2 1 105 pixel 3 2 110 pixel 4 3 115 pixel 5 4 120

Pixel number Distance d Grayscale value G pixel 1 0 120 pixel 2 1 115 pixel 3 2 110 pixel 4 3 105 pixel 5 4 100

On the A module side, the grayscale value increases as it moves away from the boundary. This is to gradually increase the grayscale value to reach 120, which is the normal grayscale value inside the module.

On the B module side, the grayscale value decreases as it moves away from the boundary. This is to gradually lower the grayscale value to reach 100, which is the normal grayscale value inside the module.

By gradually adjusting the grayscale values in this way, the brightness changes around the border can be smoothly connected, minimizing visual dissonance.

Figure 5 is a block diagram illustrating a detailed structure of the brightness deviation correction device of Figure 1.

As illustrated in FIG. 5, the brightness deviation correction device (110) of FIG. 1 according to an embodiment of the present invention includes part or all of a communication interface unit (500), a control unit (510), a brightness deviation correction unit (520), and a storage unit (530).

Here, the expression “including some or all” means that some components, such as the storage unit (530), may be omitted to configure the brightness deviation correction device (110), or some components, such as the brightness deviation correction unit (520), may be integrated into other components, such as the control unit (510), and is explained as including all in order to help sufficient understanding of the invention.

The communication interface unit (500) can communicate with the LED display device (100) as shown in Fig. 1, and, for example, when a brightness deviation correction device (110) is provided in a set-top box, etc., it can perform an operation for receiving an advertising image from the outside. In addition to the method of receiving an advertising image by connecting to a remote server such as a cloud server, it is also possible to receive the advertising image locally, that is, through a nearby computer, etc. Of course, in the case of transmitting an advertising image such as an electronic billboard, it is also possible to communicate with a computer, etc. to receive the image data of the advertising image. For example, it is also possible to connect a storage medium (e.g., USB) in which the advertising image is stored.

The control unit (510) includes a processor such as a CPU, an MPU, a GPU, and may further include a memory such as a RAM. The processor and the memory may also be configured as a single chip in the form of an IC chip, etc. The control unit (510) may perform the overall control operation of the communication interface unit (500), the brightness deviation correction unit (520), and the storage unit (530) of FIG. 5. The control unit (510) may pre-store image data such as an advertising image and then transmit it to the LED display device (100) of FIG. 1. At this time, the control unit (510) transmits image data in which the brightness deviation of the boundary portions facing each other and physically separated when the LED display device (100) is configured with a plurality of LED panels in conjunction with the brightness deviation correction unit (520), and may control the communication of the communication interface unit (500) for this purpose. The communication interface unit (500) may be connected to an HDMI cable, etc., and may process image data in which the brightness deviation is corrected. Of course, in the embodiment of the present invention, it has been exemplified that correction data is provided to the LED display device (100) so that correction of image data is performed accordingly.

The brightness deviation correction unit (520) corrects the brightness deviation that occurs at the boundary portions that are physically separated from each other when an LED display device (100) such as an electric signboard is configured by arranging multiple LED panels in a matrix form in a serial form, so that an image is implemented by the corrected image data. In other words, multiple LED panels can implement an image of one unit video frame on the screen, and by implementing 30 to 120 video frames per second, an advertising image in the form of a moving picture can be implemented on the screen. At this time, a brightness deviation may occur at the boundary portions that face each other between adjacent LED panels that are physically separated from each other, and the brightness deviation correction unit (520) can be considered to correct this. In other words, it can be considered that the brightness deviation between adjacent panels at the boundary portions becomes uniform through the correction.

To this end, the brightness deviation correction unit (520) according to the embodiment of the present invention operates to differentially apply a correction coefficient to each pixel through a correction formula, as sufficiently explained above with reference to FIGS. 3 to 4c, in other words, to differentially apply a correction coefficient to each pixel of the boundary area by preset sections, so that even if the same gamma value is input, the amount of brightness displacement is different and the consistency of the same brightness is secured. For example, the brightness deviation correction unit (520) can obtain a correction formula based on the brightness value corresponding to the grayscale of each section after a threshold value is set. Then, constants A and B are obtained through the correction formula according to each threshold value. The collected brightness value of the boundary pixel can be inversely calculated through the correction formula to obtain the corresponding gamma value, and it can be determined whether the gamma value at this time is greater than or less than the preset threshold value. If the gamma value exceeds the threshold value, the weight of the boundary pixel is set to 1, which means that it does not change. If not exceeded, the correction formula corresponding to the grayscale of the boundary pixel is applied, the gamma value is substituted, and the calculated value is used as the final correction coefficient. Once the final correction coefficient is derived through this process, it is applied to each pixel to perform the correction. More precisely, the correction data generated by differentially applying the correction coefficient through the correction formula can be output. The correction data can include the constant of the correction formula, the modified correction coefficient, and the grayscale value to which the gradient is applied.

The storage unit (530) can store image data such as advertisement images under the control of the control unit (510), and can also store gamma values in the form of a gamma table, etc. The gamma values in the gamma table can be output under the control of the control unit (510) when requested by the brightness deviation correction unit (520). Of course, the storage unit (530) can store various types of data in addition to these.

In addition to the above, the communication interface unit (500), control unit (510), brightness deviation correction unit (520), and storage unit (530) of Fig. 5 can perform various operations, and other detailed information has been sufficiently explained above, so those contents will be used instead.

Meanwhile, the communication interface unit (500), the control unit (510), the brightness deviation correction unit (520), and the storage unit (530) of FIG. 5 according to the embodiment of the present invention are configured as hardware modules that are physically separated from each other, but each module may store software for performing the above operations therein and execute the same. However, the software is a collection of software modules, and each module may be formed of hardware, so there will be no particular limitation on the configuration such as software or hardware. For example, the storage unit (530) may be hardware, such as storage or memory. However, since it is also possible to store information (repository) in a software manner, there will be no particular limitation on the above.

In addition, as another embodiment of the present invention, the control unit (510) may include a CPU and a memory, and may be formed as a single chip. The CPU may include a control circuit, an operation unit (ALU), a command interpretation unit, and a registry, and the memory may include a RAM. The control circuit may perform a control operation, the operation unit may perform an operation of binary bit information, and the command interpretation unit may perform an operation of converting a high-level language into a machine language and vice versa, including an interpreter or a compiler, and the registry may be involved in software data storage. According to the above configuration, for example, at the beginning of the operation of the brightness deviation correction device (110) of FIG. 1, the program stored in the brightness deviation correction unit (520) may be copied and loaded into the memory, that is, the RAM, and then executed, thereby rapidly increasing the data operation processing speed. In the case of a deep learning model, it may be loaded into the GPU memory instead of the RAM and executed by accelerating the execution speed using the GPU.

FIG. 6 is a flowchart showing the driving process of a correction device for correcting brightness deviation of an LED display according to an embodiment of the present invention.

For convenience of explanation, referring to FIG. 6 together with FIG. 1, the brightness deviation compensation device (110) of FIG. 1 according to an embodiment of the present invention is a compensation device for compensating for brightness deviation of an LED display, and can store brightness value data corresponding to the grayscale of each pixel of a boundary surface related to a boundary area between LED panels that are physically separated and adjacent to each other in relation to a plurality of LED panels constituting an LED display device (100) (S600). Here, the brightness value data may be, for example, a brightness value per cabinet (or cabinet), an average brightness value corresponding to a grayscale value measured and collected during a calibration process during LED production, and the average brightness value may be utilized. Of course, since the brightness value may be obtained through various routes, the embodiment of the present invention will not be particularly limited to any one form.

In addition, the brightness deviation correction device (110) of FIG. 1 according to an embodiment of the present invention divides the brightness value data and grayscale sections to be stored into a plurality of sections (e.g., linear sections and nonlinear sections, etc.), and generates different correction formulas to be applied to each section, and uses the correction formulas of each section generated to generate correction data for correcting each pixel of the boundary surface of the boundary area, and outputs the data for use in the LED display device (100) (S610).

For example, the grayscale range of each pixel in the boundary area may be divided into two or more sections of low brightness and high brightness, and compensation data may be generated for differential application to each section by a compensation formula generated based on preset low brightness thresholds, high brightness thresholds, grayscales in each section, and brightness values corresponding to the grayscales, and provided for use in compensation of boundary pixels in the boundary area. Here, the compensation data may include constants of the compensation formula (e.g., A, B, C, etc.), modified compensation coefficients, and grayscale values to which gradients are applied. Such compensation data may be provided so that a control device such as an FPGA of the LED display (device) (100) may utilize it to compensate for image data. Typically, grayscale may mean 256 brightness levels (e.g., 8 bits) of black and white without color, and when looking at values from 0 to 255, 0 may represent complete black and 255 may represent complete white. Grayscale may also be called a tone value.

The brightness deviation correction device (110) according to an embodiment of the present invention can operate in various forms. In other words, the operation process, such as generating a grayscale-brightness nonlinear graph and deriving a correction formula for each section, which has been described above with reference to FIG. 3, can be preset (or pre-made) through a program, etc., and thus the brightness deviation correction device (110) can transmit correction data generated by executing the pre-generated graph and correction formula, etc. to a control device, such as an FPGA, of the LED display (device) (100).

In addition to the above, the correction device for correcting brightness deviation of an LED display according to an embodiment of the present invention, including the brightness deviation correction device (110) of FIG. 1, can perform various operations, and other detailed information has been sufficiently explained above, so it will be replaced with those contents.

Even though all the components constituting the embodiments of the present invention have been described as being combined as one or operating in combination, the present invention is not necessarily limited to such embodiments. That is, within the scope of the purpose of the present invention, all of the components may be selectively combined and operated one or more times. In addition, although all of the components may be implemented as independent hardware, some or all of the components may be selectively combined and implemented as a computer program having program modules that perform some or all of the functions combined in one or more hardware. The codes and code segments constituting the computer program may be easily inferred by a person skilled in the art of the present invention. Such a computer program may be stored in a non-transitory computer readable medium and read and executed by a computer, thereby implementing the embodiments of the present invention.

Here, the non-transitory readable storage medium means a medium that semi-permanently stores data and can be read by a device, rather than a medium that stores data for a short period of time, such as a register, cache, or memory. Specifically, the above-described programs can be stored and provided on a non-transitory readable storage medium, such as a CD, DVD, hard disk, Blu-ray disk, USB, memory card, or ROM.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and various modifications may be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims. Furthermore, such modifications should not be individually understood from the technical idea or prospect of the present invention.

100: LED display device 110: Brightness deviation correction device
500: Communication interface section 510: Control section
520: Brightness deviation correction unit 530: Storage unit

Claims (12)

A storage unit that stores brightness value data corresponding to the grayscale of each pixel of a boundary between a plurality of LED panels that are physically separated and placed adjacent to each other in an LED display device; and
A control unit that divides the grayscale section into multiple sections using the stored brightness value data and the gamma value corresponding to the grayscale, generates different correction formulas for applying to each section, and generates correction data for correcting each pixel of the boundary of the gap area using the correction formulas of each section generated, and outputs the data for use in the LED display device;
A correction device for correcting brightness deviation of an LED display, including: In the first paragraph,
The above control unit is a correction device for correcting brightness deviation of an LED display, which stores and uses an average brightness value corresponding to a grayscale value measured and collected for each LED panel during the calibration process during the production of the LED display device as the brightness value data. In the first paragraph,
The above control unit sets a first threshold value and a second threshold value for dividing the above sections, respectively, and then divides each section into a linear section and a nonlinear section based on the set first threshold value and the second threshold value, and generates a correction formula based on the brightness value corresponding to the grayscale in the divided linear section and nonlinear section, respectively, for correcting the brightness deviation of the LED display. In the third paragraph,
The above control unit calculates the corresponding gamma value (gamma) by inversely calculating the brightness value collected for each pixel of the above boundary surface through the above correction formula, determines whether the obtained gamma value is larger or smaller than a preset threshold value, and when the determination result is smaller, applies the correction formula and substitutes the obtained gamma value to calculate the calculated value as a final correction coefficient so that the calculated final correction coefficient is used as the correction data. This is a correction device for correcting the brightness deviation of an LED display. In the first paragraph,
The above control unit sets a pixel range for applying gradation centered on the boundary line of the gap area by using the grayscale values and brightness values of pixels around the boundary line of the gap area between the adjacently arranged LED panels, and changes the grayscale values of pixels in the set pixel range in stages according to preset conditions as the distance from the boundary line increases, and recalculates the brightness value of each pixel based on the changed grayscale values so that the brightness of each pixel is corrected with the recalculated brightness value. This is a correction device for correcting brightness deviation of an LED display. In paragraph 5,
A correction device for correcting brightness deviation of an LED display, wherein the control unit provides data including a constant of the correction formula, a modified correction coefficient, and a grayscale value applied to the gradient as the correction data to the control device of the LED display device. A step for storing brightness value data corresponding to the gray scale of each pixel of a boundary between a plurality of LED panels that are physically separated and placed adjacent to each other in relation to a plurality of LED panels that constitute an LED display device; and
A step of the control unit dividing the grayscale section into a plurality of sections using the stored brightness value data and the gamma value corresponding to the grayscale, generating different correction formulas for applying to each section, and generating correction data for correcting each pixel of the boundary of the gap section using the correction formulas of each section generated, and outputting the data for use in the LED display device;
A method for driving a correction device for correcting brightness deviation of an LED display, comprising: In Article 7,
The above saving steps are:
A method for driving a correction device for correcting brightness deviation of an LED display, wherein the average brightness value corresponding to the grayscale value measured and collected for each LED panel during the calibration process during the production of the LED display device is stored and used as the brightness value data. In Article 7,
The steps for generating each of the above correction formulas are:
A method for driving a correction device for correcting brightness deviation of an LED display, wherein a first threshold value and a second threshold value are set for distinguishing the above sections, and each section is distinguished into a linear section and a nonlinear section based on the first threshold value and the second threshold value set above, and a correction formula is generated based on the brightness value corresponding to the grayscale in the distinguished linear section and nonlinear section, respectively. In Article 9,
The above output step is,
A step of calculating the brightness value collected for each pixel of the above boundary surface inversely using the above correction formula to obtain the corresponding gamma value; and
A step of determining whether the above-determined gamma value is greater than or less than a preset threshold value, applying the above-determined gamma value to the correction formula when the determination result is smaller, and calculating the calculated value as the final correction coefficient so that the above-determined final correction coefficient is used as the correction data;
A method for driving a correction device for correcting brightness deviation of an LED display, comprising: In Article 7,
The above output step is,
A step of setting a pixel range for applying a gradient centered on the boundary line of a gap area by using the grayscale values and brightness values of pixels around the boundary surface of a gap area between adjacently arranged LED panels;
A step of gradually changing the grayscale value of pixels in the above-described pixel range according to preset conditions as the distance from the boundary increases; and
A step of recalculating the brightness value of each pixel based on the changed grayscale value and correcting the brightness of each pixel with the recalculated brightness value;
A method for driving a correction device for correcting brightness deviation of an LED display, comprising: In Article 11,
The above output step is,
A method for driving a correction device for correcting brightness deviation of an LED display, comprising the step of providing data including a constant of the correction formula, a modified correction coefficient, and a grayscale value applied to the gradient as the correction data to a control device of the LED display device.