A point-by-point correction method for LED lights in special-shaped curved screens

Abstract

The present invention discloses a point-by-point correction method for LED lamps in a special-shaped curved screen, and realizes the consistency of brightness and chromaticity displayed by the entire special-shaped curved screen through two corrections; specifically, the first correction is to collect and classify images of all LED light boards, and then set correction parameters for all light boards as a whole and store them in the memory of each LED light board, and when the display screen is assembled and driven, the correction of the brightness and chromaticity of each LED lamp bead is realized by reading the correction parameters of each LED light board, thereby realizing the consistency of brightness and chromaticity display of all the same LED light boards on the display screen; the second correction is to collect brightness and chromaticity values ​​of different LED light boards with the LED light board as a unit, and calculate new correction values, and the driving circuit corrects the entire display screen for the second time according to the new correction value, thereby realizing the consistency of brightness and chromaticity displayed by the entire display screen.

Description

Technical Field

[0001] The present invention belongs to the technical field of LED display correction, and more specifically, relates to a point-by-point correction method for LED lamps in a special-shaped curved screen. Background Art

[0002] LED (Light Emitting Diode) display screens are designed with semiconductor light emitting diodes as the main components. Due to its advantages of high brightness, high contrast, long life and arbitrary customization of display size, it has been widely used in outdoor commercial advertising and display, building curtain walls, airport station traffic guidance, indoor conference display, dispatch command display, school hospital information broadcast and other scenarios. With the continuous advancement and development of LED display technology, the demand for special application scenarios that require small pitch, high density, high refresh rate and high reliability is becoming more and more extensive. For example, in the ball screen visual display system in the field of flight simulation, the existing immersive ball screen visual display system is mostly realized by projection display technology, and the ball screen or ball belt screen display function is realized by multiple projectors in the form of image splicing and fusion. Projection technology belongs to passive display technology. In the ball screen visual display system, there are generally problems such as low display brightness, low contrast, low channel image pixel utilization, complex image processing, inability to achieve full field of view due to light path occlusion, short life and difficult maintenance. In order to improve and solve these problems, a ball screen visual display solution based on LED display technology is proposed.

[0003] The LED-based ball screen or ball strip screen uses semiconductor light-emitting diodes as the basic display element, designs and processes LED light panels of different shapes, and then splices them into a spherical display screen. Finally, the LED is driven by video image processing technologies such as geometric correction and seamless splicing of multi-channel video images, and finally presents a continuous spherical visual picture. A display system. Due to its advantages of high brightness, high contrast, wide color gamut, high refresh rate and full field of view, it can present a better sense of immersion and realism than projection technology during flight simulation. In addition, its long life, easy maintenance and complete autonomous control make LED as a visual ball screen display system have great research significance and application value.

[0004] The LED visual ball screen used in flight simulation is an inner spherical display screen, which is a special-shaped LED display screen. Its main function is to present realistic visual scenes to pilots. Since pilots observe the entire screen at the center of the ball, not only the viewing distance is close, but also they will be in a relatively closed environment for a long time. Therefore, pilots are more sensitive to the brightness and color of the display screen. The difference in brightness and color on the display screen can easily attract the pilot's attention, which directly affects the training effect.

[0005] The main existing methods to solve the brightness and chromaticity differences of LED display screens include increasing the batch production of LED lamp beads to reduce the use of mixed batches of LED lamp beads in the same product; screening and mixing LED lamp beads to improve the consistency of the central wavelength of LED lamp beads and the discreteness of the distribution of LED lamp beads on the product; and using LED display screen point-by-point correction technology to accurately adjust each LED lamp bead to a fixed brightness and chromaticity through drive control. There is no doubt that point-by-point correction technology is the lowest cost, most efficient and best presentation method. However, the currently disclosed point-by-point correction technology of LED display screens is mainly aimed at conventional rectangular display screens, and there is little research on point-by-point correction of special-shaped LED display screens. The publication number is CN 114283097. A Chinese patent document discloses a method and device for correcting the gap light points of a special-shaped LED display screen, which is characterized in that an image of the special-shaped LED display screen is obtained, and the image coordinates of the light points at the gap position in the special-shaped LED display screen are determined according to a preset light point calculation strategy; any non-gap position light point is selected as a reference light point in the image of the special-shaped LED display screen, and a first adjacent reference light point and a second adjacent reference light point are selected for the reference light point according to a preset light point selection strategy, and the image coordinates of the reference light point, the first adjacent reference light point, and the second adjacent reference light point are determined; a reference distance parameter of the reference light point is calculated according to the image coordinates of the reference light point, the first adjacent reference light point, and the second adjacent reference light point and a preset distance parameter calculation strategy; in the Select target light points in sequence from the light points at the gap positions, and select the first adjacent target light point and the second adjacent target light point for the target light point from the light points at the gap positions according to the light point selection strategy; calculate the target distance parameters of the target light point, the first adjacent target light point and the second adjacent target light point through the image coordinates of the target light point, the first adjacent target light point and the second adjacent target light point and the distance parameter calculation strategy; calculate the correction coefficient of the light point at the gap position through the reference distance parameter, the target distance parameter and a preset coefficient correction algorithm; obtain the light point correction coefficient of the full-screen light point of the special-shaped LED display screen, and correct the light point at the gap position of the special-shaped LED display screen according to the light point correction coefficient of the light point at the gap position and the correction coefficient.

[0006] The correction method disclosed in the patent document can effectively process the splicing gap of spliced ​​special-shaped LED display screens, effectively eliminate the bright or dark lines during splicing, and improve the display effect of the special-shaped LED display screen. However, the special-shaped LED display screen described in the patent document is mainly a special-shaped screen spliced ​​by parallelogram-like boxes, and the main problem to be solved is the bright and dark lines at the splicing gap of the box. However, this method still cannot achieve point-by-point correction for some special-shaped special-shaped display screens, such as spherical or hyperbolic display screens. So far, there is no method to achieve point-by-point correction of spherical or hyperbolic display screens. The main reasons include that this type of screen is made up of LED light boards of various shapes. Each LED light board not only has a different shape, but also has a different internal LED arrangement. Its arrangement is no longer the common matrix arrangement, but a point-by-point arrangement along the curvature of the sphere or hyperboloid. In addition, when the LED light board is in a flat state, the spacing between LED lamp beads is one state. When the LED light board is spliced ​​with a spherical or hyperbolic deformation, the spacing between LED lamp beads will change due to extrusion deformation. Therefore, the spacing between LED lamp beads in the spherical or hyperbolic case is no longer evenly distributed. Finally, when the sphere or hyperbolic surface is large, the camera cannot capture the entire screen at once, and point-by-point correction of the entire screen cannot be achieved. When regional correction is used, there will be problems with image fusion and correction at the boundary of the acquisition area, making the algorithm more complicated.

[0007] Therefore, how to effectively collect the LED brightness and chromaticity parameters and coordinate parameters on the spherical or hyperbolic LED display screen, and map them one by one with the pixel points of the image to be displayed, and finally realize the point-by-point correction of the entire spherical or hyperbolic LED display screen is an urgent problem to be solved by people in this field. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a point-by-point correction method for LED lights in a special-shaped curved screen. By rearranging the light points of the collected spherical or arc-shaped curved screens, the mapping between image pixels and LED lamp beads is effectively solved, and then after two corrections, the consistency of brightness and chromaticity display of the special-shaped curved screen is achieved.

[0009] To achieve the above-mentioned purpose of the invention, the present invention provides a method for point-by-point calibration of LED lights in a special-shaped curved screen, characterized in that it comprises the following steps:

[0010] (1) Divide the special-shaped curved screen to be corrected into LED light boards of various shapes along the longitude and latitude division method, each LED light board is in the shape of a fan, and the LED lamp beads in each LED light board are arranged along the fan-shaped arc;

[0011] (2) Number each LED light board by type, from top to bottom as H1, H2, ...H n,n represents the number of types of LED light boards. The shapes of LED light boards with the same number and the arrangement of the internal LED lamp beads are exactly the same;

[0012] (3) According to the actual position of each type of LED light board in the special-shaped curved screen, a corresponding arc structure is set, wherein each type of LED light board corresponds to an arc structure; and a memory is set on each LED light board;

[0013] (4) Install a single LED light board on the corresponding arc structure, drive the LED light board and obtain the image of the LED light board through the image capture device, then replace the same type of LED light board, repeat the operation until the image acquisition of the same type of LED light board is completed; then replace another arc structure, and install the corresponding type of LED light board in turn and drive it until the images of all LED light boards are acquired;

[0014] (5) Recording the image of the LED lamp bead in each LED light board image as a light point, then recalculating and arranging the light points in each type of LED light board image, and saving the LED light board number and the rearranged light point coordinates in a memory;

[0015] (6) Set calibration parameters Among them, R r Indicates the coefficient for adjusting the red lamp luminous intensity when correcting for red, R g Indicates the coefficient for adjusting the green lamp luminous intensity when correcting for red, R b Indicates the coefficient of adjusting the luminous intensity of the blue lamp when correcting for red. Similarly, G r , G g , G b With B r , B g , B b They are the coefficients of the red, green and blue lamp luminous intensity that need to be adjusted for green correction and blue correction respectively;

[0016] The correction parameter K is stored in a memory provided in each LED light board;

[0017] (7) Assemble each LED light board into a special-shaped curved screen according to the number, and calibrate the brightness and color value of the LED light board after installation;

[0018] (7.1) The video receiving card reads the number, light point coordinates and calibration parameter K of each LED light board;

[0019] (7.2) Taking the LED light boards with the same number as the unit, firstly perform pixel sampling on the LED light board image in rows according to the number of the LED light board and the coordinates of the light point, and then drive each LED light point according to the pixel point to realize the mapping between each LED light point and the image pixel; finally, adjust the brightness and chromaticity value of each LED light point point by point through the correction parameter K;

[0020] (8) Correct the overall brightness and chromaticity value of the special-shaped curved screen;

[0021] (8.1) Generating correction parameters for brightness and chromaticity values;

[0022] (8.1.1) Collect brightness and chromaticity data;

[0023] Drive the entire special-shaped curved screen, place a brightness and chromaticity acquisition instrument at the center of the special-shaped curved screen, and then use a single LED light board as a unit to collect brightness and chromaticity data of LED light boards with different numbers in sequence;

[0024] (8.1.2) Generate brightness and chromaticity correction parameters by analyzing brightness and chromaticity data;

[0025] (8.1.2.1) Brightness correction parameter: set the target brightness value of LED light boards with different numbers according to the brightness values ​​of all LED light boards collected, and then adjust the brightness values ​​of LED light boards with different numbers to the adjustment parameters of the target brightness value as the brightness correction parameter;

[0026] (8.1.2.2) Chromaticity correction parameters: Collect the R, G, and B values ​​of each LED light board and mark them in the color gamut coordinates; connect the three chromaticity coordinate values ​​of R, G, and B of each LED light board to form a triangular area, thereby obtaining multiple triangular areas, and then find the common area after the triangular areas are superimposed, and use the R, G, and B values ​​corresponding to the common area as the target value and calculate the chromaticity correction parameters of each LED light board;

[0027] (8.2) Correct the overall brightness and chromaticity values ​​of the special-shaped curved screen according to the brightness and chromaticity correction parameters;

[0028] Taking a single LED light board as a unit, the brightness and chromaticity data of LED light boards with different numbers are corrected in turn through the brightness and chromaticity correction parameters, and the correction parameters are stored in the video sending device, thereby completing the brightness and chromaticity correction of the special-shaped curved screen.

[0029] The object of the invention of the present invention is achieved in this way:

[0030] The present invention discloses a point-by-point correction method for LED lamps in a special-shaped curved screen, which realizes the consistency of brightness and chromaticity displayed by the entire special-shaped curved screen through two corrections; specifically, the first correction is to collect and classify images of all LED light boards, and then set correction parameters for all light boards as a whole and store them in the memory of each LED light board, and when the display screen is driven after being assembled, the correction parameters of each LED light board are read to realize the correction of the brightness and chromaticity of each LED lamp bead, thereby realizing the consistency of brightness and chromaticity display of all the same LED light boards on the display screen; the second correction is to collect brightness and chromaticity values ​​of different LED light boards with the LED light board as a unit, and calculate new correction values, and the driving circuit corrects the entire display screen for the second time according to the new correction values, thereby realizing the consistency of brightness and chromaticity displayed by the entire display screen.

[0031] At the same time, the point-by-point correction method of LED lights in a special-shaped curved screen of the present invention also has the following beneficial effects:

[0032] (1) The present invention realizes point-by-point correction of the brightness and chromaticity of the special-shaped curved display screen by two correction methods. On the one hand, it can effectively solve the limitation that single-module correction can only be applicable to module units that are completely the same, and achieves the purpose of achieving consistent brightness and chromaticity of the entire screen after different types of modules are calibrated and assembled into a whole screen; on the other hand, it can also solve the problem that the entire screen image cannot be obtained at one time when the special-shaped curved screen is calibrated, the clarity of the obtained image is inconsistent due to lens reasons, and there are a series of problems such as post-image splicing and fusion after the regional image is obtained, which leads to inaccurate brightness and chromaticity acquisition data and difficulty in calculating the coordinates of the light points.

[0033] (2) The present invention stores the first calibration parameters directly on each LED light board, which not only ensures that the LED light boards used on the screen can be calibrated to be consistent, but also allows spare LED light boards to be quickly adjusted to be consistent with the display screen. Therefore, there is no need to consider the differences in LED light boards during installation and maintenance, and the first calibration can be completed in the factory, which can greatly shorten the on-site installation and debugging time. Since the second calibration parameters are for the entire screen, the advantage of storing them in the video sending device is that when the LED light board is replaced later, no additional calibration is required to achieve the replaced LED light board being adjusted to be consistent with the brightness and color of the entire display screen. Therefore, the secondary calibration of the present invention and the storage of the calibration parameters in the LED light board and the sending device respectively can greatly simplify the entire screen installation and debugging process as well as the complexity of the subsequent LED light board maintenance.

[0034] (3) The present invention can effectively solve the problem of fixed point positioning during point-by-point correction of special-shaped curved screens through the LED light point rearrangement method. The LED light point rearrangement algorithm can quickly and accurately identify the light points arranged along the arc and arrange them into a matrix form, thereby realizing the mapping of later image pixels and LED light points and adjusting the chromaticity value of LED light points point by point.

[0035] (4) The present invention only collects the brightness and chromaticity values ​​of a single light board during the secondary calibration process, and adjusts the chromaticity values ​​of the entire screen with the common color gamut as the target, which has the advantages of being fast and accurate. Finally, during the on-site debugging process, only secondary calibration is required to achieve a brightness uniformity of 95% for the entire special-shaped curved screen, and the color coordinate error is adjusted to no more than 0.05.

[0036] (5) Compared with the prior art, the existing point-by-point correction technology of the present invention is only applicable to regular rectangular display screens, and the existing technology is no longer applicable to the field of spherical or curved screens, especially the technical difficulty of being unable to achieve the fixed point position during the point-by-point correction process; the present invention effectively solves the mapping between image pixels and LED lamp beads by arranging the light points of the collected spherical or curved screens, and then after two corrections, the consistency of brightness and chromaticity display of the curved screen is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of a method for point-by-point correction of LED lights in a special-shaped curved screen of the present invention;

[0038] Figure 2 is a schematic diagram of a single LED image acquisition device;

[0039] Figure 3 This is a schematic diagram of rearranging LED light points;

[0040] Figure 4 This is a schematic diagram of the brightness and chromaticity of different types of LED light panels after the first calibration;

[0041] Figure 5 This is a schematic diagram of collecting brightness and chromaticity data of a single LED light panel in a special-shaped curved screen;

[0042] Figure 6 It is the color gamut diagram of a single LED light board;

[0043] Figure 7 These are the color gamut diagrams of multiple LED light boards. DETAILED DESCRIPTION

[0044] The specific implementation of the present invention is described below in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0045] Example

[0046] Figure 1 The present invention is a flow chart of a method for point-by-point correction of LED lamps in a special-shaped curved screen.

[0047] In this embodiment, if Figure 1 As shown, the present invention provides a point-by-point correction method for LED lights in a special-shaped curved screen, comprising the following steps:

[0048] S1, LED light panels are divided and arranged;

[0049] The special-shaped curved screen to be corrected is divided into LED light boards of various shapes along the longitude and latitude division method, each LED light board is in the shape of a fan, and the LED lamp beads in each LED light board are arranged along the fan-shaped arc;

[0050] S2, LED light board number;

[0051] Each LED light board is numbered by type, from top to bottom as H1, H2, ...H n ,n represents the number of types of LED light boards. The shapes of LED light boards with the same number and the number and arrangement of internal LED lamp beads are exactly the same;

[0052] In this embodiment, if the special-shaped curved screen to be corrected has 3840 rows, each LED light board can be designed to have 192 rows. Then, 20 types of LED light boards can be spliced ​​into 3840 rows along the longitude and latitude division method. 3840 rows can correspond to the number of rows of the 2160 (W) × 3840 (H) resolution rectangular figure. The 20 types of LED light boards are numbered H1, H2, ... H from top to bottom. 20 At the same time, in order to display 2160 columns of image data, the widest part (equator) of the LED light board can be designed to have 80 points, so 27 LED light boards are needed in the equatorial area to achieve 2160 pixels. Due to the characteristics of the hyperbolic surface, the number of LED light boards with the same number decreases as you move toward the pole.

[0053] S3, setting an arc structure and a memory;

[0054] The arc structure is a single module structure that is the same as the structure of the corresponding area of ​​the special-shaped curved screen. Since the LED light board is set into various shapes, the arc structure is also set into various shapes. The function of the arc structure is to ensure that the deformation of the LED light board installed thereon is the same as the deformation of the corresponding position installed on the special-shaped curved display screen;

[0055] In this embodiment, in order to ensure that the LED light board can be assembled into the desired special-shaped curved screen, a high-precision aluminum die-casting tray is provided, and the LED light board is installed on the aluminum die-casting tray by magnetic attraction, and hyperboloid deformation is performed along the edge of the aluminum die-casting tray, so that the LED light board can be quickly replaced and driven; at the same time, an interface conversion board and a video receiving card are arranged in the aluminum die-casting tray, and the LED light board is connected to the interface conversion board through a floating connector, thereby realizing the power supply and video drive of the LED light board;

[0056] A memory is provided on each LED light board to store the number of each LED light board, the calibration parameters and the coordinates of each lamp bead in the LED light board after rearrangement;

[0057] S4, obtaining images of all light panels of the entire special-shaped curved screen;

[0058] Install a single LED light board on the corresponding arc structure, and install the image capture device at the center of curvature in the normal direction of the arc structure; drive the LED light board and obtain the image of the LED light board through the image capture device, then replace the same type of LED light board, and repeat the operation until the image acquisition of the same type of LED light board is completed; then replace another arc structure, and install the corresponding type of LED light board in turn and drive it until the images of all LED light boards are obtained;

[0059] In this embodiment, if Figure 2 As shown, a single LED light board 10 is installed on the arc structure 20, and the arc structure 20 is installed on the set fixing device 30. The fixing device 30 is provided with an adjustable locking device 301, so that the arc structure 20 can realize pitch angle adjustment on the fixing device 30. When capturing an image, first adjust the pitch angle of the arc structure 20 so that the horizontal indication device 201 provided on the arc structure 20 indicates a horizontal state; install the LED light board and drive it, place the image capture device 40 at a distance R from the light board, and the image capture device 40 collects the image of the LED light board until all the images of the same LED light board are acquired; replace another arc structure, install the corresponding LED light board and drive it, and then acquire the image of this LED light board; replace the arc structure and the LED light board according to the above steps to complete the acquisition of all LED light board images.

[0060] S5, rearrange the light points in the LED light board image;

[0061] The image of the LED lamp bead in each LED light board image is recorded as a light point, and then the light points in each type of LED light board image are recalculated and arranged, and the number of the LED light board and the rearranged light point coordinates are saved in a memory;

[0062] In this embodiment, since the captured LED light point image is non-rectangular and has the characteristic of being arranged along the arc edge, there is a problem that the LED light points cannot be mapped one-to-one with the image pixels during the point-by-point correction process, and there is a problem of the fixed position of the LED light points. Therefore, the present invention can effectively solve this problem by recalculating the arrangement of the LED light points, which is as follows:

[0063] S5.1, binarize each LED light board image to obtain a binary image; Figure 3 As shown in the left figure, on each binary image, the rectangular coordinate system XOY is set to ensure that the X axis is parallel to the tangent line of the outer arc of the fan;

[0064] S5.2. Extend the radius of the sector to get the center point C, and record the coordinates of point C (x c ,y c ), and record the coordinates of each LED light point at the same time;

[0065] S5.3. In each binary image, first find the point with the smallest Y-axis coordinate, such as Figure 3 As shown in the middle left figure, the point with the smallest Y-axis coordinate is Then calculate the distance from point C to point L i1 Distance Then, we start from the point with the smallest X-axis coordinate and calculate the distance between each light point and point C. The distance between the i-th light point and point C is recorded as R i ;

[0066] Create a new rectangular coordinate system XOY and set the distance threshold T r ; if |R1-R i |≤T r , then add the i-th light point in the new rectangular coordinate system XOY and reassign the new coordinates The values ​​of are all integers; then add the next light point that meets the conditions to the new rectangular coordinate system XOY and reassign new coordinates Then repeat this process until all the light points are traversed;

[0067] In this embodiment, if Figure 3 As shown in the left figure, if the query finds point L 11 (x1,y1) satisfies the condition, then Figure 3 The new rectangular coordinate system XOY shown in the middle right figure is added and reassigned to coordinates: Since this is the first light point added, Assign a value of 1, that is, point L 11 The horizontal and vertical coordinate values ​​of (x1, y1) in the new rectangular coordinate system XOY are both 1;

[0068] Assuming that the distance between the LED lamp beads is designed to be 1.5 mm, the threshold can be set to the distance threshold T r =1.5×80%=1.2, which means that all LED light points arranged along the same arc can be identified and rearranged into a row;

[0069] S5.4. After the first round of traversal is completed, we can Figure 3 The light points in the first row close to the X-axis in the left image are queried and rearranged to complete a row of light points, and then the light points with new coordinates reassigned in the binary image (i.e., the light points in the first row close to the X-axis) are deleted, and then step S5.3 is repeated to perform a second round of traversal, and so on;

[0070] S5.5. Save the coordinates of each light point in the new rectangular coordinate system XOY and the number of the corresponding LED light board in the memory.

[0071] S6. Set calibration parameters Among them, R r Indicates the coefficient for adjusting the red lamp luminous intensity when correcting for red, R g Indicates the coefficient for adjusting the green lamp luminous intensity when correcting for red, R b Indicates the coefficient of adjusting the luminous intensity of the blue lamp when correcting for red. Similarly, G r , G g , G b With B r , B g , B b These are the coefficients of the red, green and blue lamp luminous intensity that need to be adjusted for green calibration and blue calibration, and these coefficients are all normalized. Each LED lamp bead corresponds to a calibration parameter K, and finally the calibration parameter K is stored in the memory set in each LED lamp board;

[0072] S7. Assemble each LED light board into a special-shaped curved screen according to the number, and calibrate the brightness and color value of the LED light board after installation;

[0073] S7.1. The video receiving card reads the number, light point coordinates and calibration parameter K of each LED light board;

[0074] S7.2, taking the LED light boards with the same number as units, firstly extracting pixels of the LED light board image in units of rows according to the number of the LED light board and the coordinates of the light points, and then driving each LED light point according to the pixel points to realize the mapping of each LED light point to the image pixel;

[0075] In this embodiment, if the total number of light boards with a certain number is 15, and the number of light points in the first row read is 50, then the total number of light points in the first row is 750. There are 2160 pixels in the first row of the rectangular image, and the 2160 pixels are compressed to 750 pixels through the sampling algorithm. The sampling algorithm includes but is not limited to neighboring interpolation, bilinear interpolation and bicubic interpolation, etc. Finally, the receiving card maps the compressed 750 image pixels to the corresponding light points of each LED light board for display. Similarly, each row of the rectangular image is compressed and mapped by the sampling algorithm, and the sampling algorithm parameters for each row may be the same or different, and finally the mapping of the pixels of the entire rectangular image to the LED light points of the special-shaped curved screen is realized.

[0076] Then adjust the brightness and chromaticity value of each LED light point point by point through the correction parameter K. The specific correction process is as follows:

[0077] In this embodiment, each LED lamp bead is mainly composed of a lamp core that can emit three basic colors: red (R), green (G), and blue (B). By using the color mixing principle, the intensity of the three colors of R, G, and B is controlled to achieve different colors of the LED lamp bead. This is also the basic principle of LED color display. Therefore, for each LED lamp, there are three values ​​of RGB, which can be recorded as a 3×1 matrix, such as Due to the differences in RGB lamp core production and the influence of many factors such as post-production processing, even if the same driving circuit and control pulse are used, the color brightness and color coordinates displayed by each LED lamp bead will deviate. Therefore, for each LED lamp bead, in order to correct the red R component, in addition to adjusting the R brightness, it is usually necessary to adjust the G and B values ​​to compensate for the deviation of the color coordinates. Therefore, when correcting the R color, it is necessary to adjust the R original value R in Multiply by three correction factors (R r , R g , R b ) to achieve adjustment. Similarly, for the same LED lamp bead, the green (G) component and the blue (B) component need to be adjusted in the same way. Therefore, for an LED lamp bead, there is a 3×3 matrix correction parameter The calibration process is: Among them, R in , G in , B in Respectively represent the red, green and blue values ​​of the original image output by the video source, R out , G out , B out They respectively represent the red, green, and blue values ​​that need to be displayed on the LED after calibration.

[0078] After the first calibration is completed, the brightness and chromaticity values ​​of all LED light panels with the same number are adjusted to be consistent. S8. Correct the overall brightness and chromaticity values ​​of the special-shaped curved screen;

[0079] After the first calibration is completed, Figure 4 As shown, the LED light panels with the same number can be calibrated to be consistent in brightness and color. For example, the brightness and color of the H1 light panel can be calibrated to be completely consistent. However, there may still be differences between H1 and H2 or H3 at this time, so a second calibration is required. The following is a detailed description of the second calibration process, as follows:

[0080] S8.1, generating correction parameters for brightness and chromaticity values;

[0081] S8.1.1. Collect brightness and chromaticity data;

[0082] The entire special-shaped curved screen is driven, and a brightness and chromaticity acquisition instrument is placed at the center of the special-shaped curved screen. Then, a single LED light board is used as a unit to sequentially acquire brightness and chromaticity data of LED light boards with different numbers. In this embodiment, Figure 5 As shown, when collecting data, you only need to select one of the LED light boards for collection. Each LED light board can collect one point, or collect multiple points and calculate the average value.

[0083] S8.1.2, generating brightness and chromaticity correction parameters by analyzing brightness and chromaticity data;

[0084] S8.1.2.1, Brightness correction parameter: set the target brightness value of the LED light panels with different numbers, and then adjust the brightness value of the LED light panels with different numbers to the adjustment parameter of the target brightness value as the brightness correction parameter;

[0085] S8.1.2.2, Chromaticity correction parameters: Collect the R, G, and B values ​​of each LED light board and mark them in the color gamut coordinates; connect the three chromaticity coordinate values ​​of R, G, and B of each LED light board to form a triangular area, thereby obtaining multiple triangular areas, and then find the common area after the triangular areas are superimposed, and use the R, G, and B values ​​corresponding to the common area as the chromaticity correction parameters;

[0086] In this embodiment, Figure 6 It is the color gamut diagram of a single LED light board, that is, the chromaticity coordinates of the three RGB colors of the light board are collected, and then the three coordinate values ​​are connected to form a triangular area. According to the color mixing principle, the LED light board can mix multiple colors from the three basic colors of RGB. However, the color gamut diagram determines that the LED light board can only display the colors within the triangular area, and the colors outside the triangular area cannot be displayed; the principle of secondary correction is to collect the color coordinates of different LED light boards, and each LED light board will form a triangle, such as Figure 7 As shown, the common area of ​​the triangle formed by all LED light boards is then obtained, and the area is used as the target adjustment value to adjust all LED light boards to only display the color of the common area, thereby achieving the correction of the chromaticity of different types of LED light boards; in this embodiment, a total of 20 types of LED light boards can obtain 20 triangular areas S1, S2 to S20, and the target chromaticity value selects the common area after the 20 triangular areas are superimposed, that is, Sp = S1∩S2∩…∩S20, and the target color coordinate values ​​of the three colors R, G, and B can be obtained according to the common area Sp;

[0087] S8.2. Correct the overall brightness and chromaticity values ​​of the special-shaped curved screen according to the brightness and chromaticity correction parameters;

[0088] Taking a single LED light board as a unit, the brightness and chromaticity data of LED light boards with different numbers are corrected in turn through the brightness and chromaticity correction parameters, and the correction parameters are stored in the video sending device to complete the secondary correction of the entire screen with the LED light board as a unit. After two corrections, the brightness and chromaticity correction of the entire special-shaped curved screen is achieved, so that the brightness uniformity of the entire screen can reach 95%, and the color coordinate error is no more than 0.05. Thus, the point-by-point correction of the LED lights in the special-shaped curved screen is completed.

[0089] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A point-by-point calibration method for LED lights in a special-shaped curved screen, characterized in that: The following steps are involved: (1) Divide the special-shaped curved screen to be corrected into LED light boards of various shapes along the longitude and latitude division method, each LED light board is in the shape of a fan, and the LED lamp beads in each LED light board are arranged along the fan-shaped arc; (2) Number each LED light board by type, from top to bottom as H1, H2, ...H n ,n represents the number of types of LED light boards. The shapes of LED light boards with the same number and the arrangement of the internal LED lamp beads are exactly the same; (3) According to the actual position of each type of LED light board in the special-shaped curved screen, a corresponding arc structure is set, wherein each type of LED light board corresponds to an arc structure; and a memory is set on each LED light board; (4) Install a single LED light board on the corresponding arc structure, drive the LED light board and obtain the image of the LED light board through the image capture device, then replace the same type of LED light board, repeat the operation until the image acquisition of the same type of LED light board is completed; then replace another arc structure, and install the corresponding type of LED light board in turn and drive it until the images of all LED light boards are acquired; (5) Recording the image of the LED lamp bead in each LED light board image as a light point, then recalculating and arranging the light points in each type of LED light board image, and saving the LED light board number and the rearranged light point coordinates in a memory; (6) Set calibration parameters Among them, R r Indicates the coefficient for adjusting the red lamp luminous intensity when correcting for red, R g Indicates the coefficient for adjusting the green lamp luminous intensity when correcting for red, R b Indicates the coefficient of adjusting the luminous intensity of the blue lamp when correcting for red. Similarly, G r , G g , G b With B r , B g , B b They are the coefficients of the red, green and blue lamp luminous intensity that need to be adjusted for green correction and blue correction respectively; The correction parameter K is stored in a memory provided in each LED light board; (7) Assemble each LED light board into a special-shaped curved screen according to the number, and calibrate the brightness and color value of the LED light board after installation; (7.1) The video receiving card reads the number, light point coordinates and calibration parameter K of each LED light board; (7.2) Taking the LED light boards with the same number as the unit, firstly perform pixel sampling on the LED light board image in rows according to the number of the LED light board and the coordinates of the light point, and then drive each LED light point according to the pixel point to realize the mapping between each LED light point and the image pixel; finally, adjust the brightness and chromaticity value of each LED light point point by point through the correction parameter K; (8) Correct the overall brightness and chromaticity value of the special-shaped curved screen; (8.1) Generating correction parameters for brightness and chromaticity values; (8.1.1) Collect brightness and chromaticity data; Drive the entire special-shaped curved screen, place a brightness and chromaticity acquisition instrument at the center of the special-shaped curved screen, and then use a single LED light board as a unit to collect brightness and chromaticity data of LED light boards with different numbers in sequence; (8.1.2) Generate brightness and chromaticity correction parameters by analyzing brightness and chromaticity data; (8.1.2.1) Brightness correction parameter: Set the target brightness value of the LED light panels with different numbers, and then adjust the brightness value of the LED light panels with different numbers to the adjustment parameter of the target brightness value as the brightness correction parameter; (8.1.2.2) Chromaticity correction parameters: Collect the R, G, and B values ​​of each LED light board and mark them in the color gamut coordinates; connect the three chromaticity coordinate values ​​of R, G, and B of each LED light board to form a triangular area, thereby obtaining multiple triangular areas, and then find the common area after the triangular areas are superimposed, and use the R, G, and B values ​​corresponding to the common area as the chromaticity correction parameters; (8.2) Correct the overall brightness and chromaticity values ​​of the special-shaped curved screen according to the brightness and chromaticity correction parameters; Taking a single LED light board as a unit, the brightness and chromaticity data of LED light boards with different numbers are corrected in turn through the brightness and chromaticity correction parameters, and the correction parameters are stored in the video sending device, thereby completing the point-by-point correction of the LED lights in the special-shaped curved screen.

2. The method for point-by-point calibration of LED lights in a special-shaped curved screen according to claim 1, characterized in that: The arc structure fixes the LED light board by magnetic attraction, and an LED driving device is also arranged on the arc structure to drive the switch of the LED light board.

3. The method for point-by-point calibration of LED lights in a special-shaped curved screen according to claim 1, characterized in that: The image capture device is installed at the center of curvature in the normal direction of the arc structure and is used to capture images of the LED light panel.

4. The method for point-by-point calibration of LED lights in a special-shaped curved screen according to claim 1, characterized in that: The method for recalculating the arrangement of the LED light points is: (4.1) Binarize each LED light board image to obtain a binary image; On each binary image, create a rectangular coordinate system XOY to ensure that the X axis is parallel to the tangent of the outer arc of the fan; (4.2) Extend the radius of the sector to get the center point C, and record the coordinates of point C (x c ,y c ), and record the coordinates of each LED light point at the same time; (4.3) In each binary image, first find the point L with the smallest Y-axis coordinate i1 (x i ,y min ), and then calculate the distance from point C to point L i1 Distance Then, we start from the point with the smallest X-axis coordinate and calculate the distance between each light point and point C. The distance between the i-th light point and point C is recorded as R i ; Create a new rectangular coordinate system XOY and set the distance threshold T r ; if |R1-R i |≤T r , then add the i-th light point in the new rectangular coordinate system XOY and reassign the new coordinates The values ​​of are all integers; then add the next light point that meets the conditions to the new rectangular coordinate system XOY and reassign new coordinates Then repeat this process until all the light points are traversed; (4.4) After the first round of traversal is completed, delete the light points with new coordinates in the binary image, and then repeat step (4.3), and so on; (4.5) The coordinates of each light point in the new rectangular coordinate system XOY and the number of the corresponding LED light board are saved in the memory.

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