A non-linear step correction method and system for projector white balance

Abstract

The application discloses a nonlinear step correction method and system for projector white balance, which comprises the following steps: obtaining the measured color coordinates and measured brightness of the projector white field and converting them into current CIE 1931 XYZ three-stimulus values; obtaining the unit pure light flux contribution rate excluding nonlinear interference based on the current theoretical light flux corresponding to the current driving current configuration value and the current three-stimulus values; constructing a matrix by using the contribution rate, obtaining the ideal light flux required for reaching the target three-stimulus values through matrix operation, and obtaining the theoretical driving current configuration value of each channel based on a preset nonlinear photoelectric characteristic function; limiting the theoretical current configuration value within the hardware safety current boundary to form a limited center point, then performing three-dimensional discrete grid traversal search based on the limited center point as a reference, performing prediction scoring screening based on the discrete current combination generated by the search and the nonlinear photoelectric characteristic function, and outputting the optimal driving current configuration value to complete the correction.

Description

Technical Field

[0001] This application relates to the field of projector color calibration technology, and in particular to a nonlinear step correction method and system for projector white balance. Background Technology

[0002] In the production and factory inspection of projector equipment, white balance calibration, which involves adjusting the driving current of the red, green, and blue light sources to ensure that the projected white field image meets the target color coordinates and brightness, is a core step that determines the optical quality of the product.

[0003] Currently, the industry's common practice is mainly based on a pure linear feedback model. Its basic logic is: measure the color coordinates of the current white field, and when a shift in the color coordinates is detected, use a fixed linear formula to directly calculate the absolute value of the current that needs to be increased or decreased.

[0004] However, the above-mentioned correction scheme based on linear assumptions has the following drawbacks in real physical scenarios: First, it ignores the nonlinear physical attenuation characteristics of the light source. When the light source is close to full load, it will produce severe light saturation and thermal attenuation effects. At this time, increasing the current will not only fail to increase the brightness proportionally, but will also increase power consumption and heat generation. The linear algorithm will completely fail in this range. Second, color accuracy and brightness cannot be achieved at the same time. The linear correction scheme usually only uses the compliance of color coordinates as the sole criterion. However, in actual calibration, simply pursuing compliance of color coordinates often leads to the brightness falling below the factory specifications. Third, there is a contradiction between continuous theoretical values ​​and discrete hardware step sizes. The projector hardware adjusts the current with discrete step sizes, while the theoretical value calculated by the linear scheme is a continuous value, which cannot be directly adapted.

[0005] Therefore, designing a white balance correction method that is effective in the nonlinear range of the light source, takes into account both color accuracy and brightness, and matches the continuous theoretical value with the discrete hardware step size is a technical problem to be solved. Summary of the Invention

[0006] This application provides a nonlinear step correction method and system for projector white balance, aiming to solve the problems of existing linear correction algorithms failing in the nonlinear range of light sources, the inability to achieve both color accuracy and brightness, and the mismatch between continuous theoretical values ​​and discrete hardware step sizes.

[0007] In a first aspect, embodiments of this application provide a nonlinear step correction method for projector white balance, comprising the following steps: The current measured color coordinates and current measured brightness of the projector white field under the current driving current configuration value are obtained, and the current measured color coordinates and current measured brightness are converted into the current CIE 1931 XYZ tristimulus values. The current theoretical luminous flux corresponding to the current driving current configuration value is also obtained. The current theoretical luminous flux is calculated by substituting the current driving current configuration value into a preset nonlinear photoelectric characteristic function. Based on the current luminous flux and the current CIE 1931 XYZ tristimulus value, the contribution rate per unit of pure luminous flux is obtained; The target CIE 1931 XYZ tristimulus values ​​are determined based on the preset target color coordinates and minimum brightness specifications. A matrix is ​​constructed using the unit pure luminous flux contribution rate, and the ideal luminous flux of the red, green, and blue channels required to achieve the target CIE1931 XYZ tristimulus value is obtained through matrix operations. Based on the aforementioned nonlinear photoelectric characteristic function and the ideal luminous flux of each channel, the theoretical driving current configuration value for each channel is obtained. The theoretical drive current configuration value of each channel is limited within a preset hardware safety current boundary, forming a restricted center point; Using the restricted center point as a reference, a three-dimensional traversal search is performed on the three current dimensions of the red channel, green channel, and blue channel within a preset number of steps to generate multiple discrete step current combinations; wherein each current value in the step current combination is an integer multiple of the current adjustment step size supported by the projector hardware. Based on the multiple discrete combinations of step currents and the nonlinear photoelectric characteristic function, the predicted color coordinates and predicted brightness corresponding to each combination are obtained. The predicted color coordinates and predicted brightness of each combination are filtered to obtain the optimal predicted color coordinates and predicted brightness, and the optimal drive current configuration value corresponding to the optimal predicted color coordinates and predicted brightness is output. The projector is calibrated based on the optimal drive current configuration value.

[0008] Preferably, the nonlinear photoelectric characteristic function is pre-established in the following manner: Before the calibration process is executed, brightness test data of each channel of multiple prototypes of the same model under different drive current configuration values ​​are collected. The brightness test data is fitted with a polynomial function using least squares to obtain the polynomial coefficients of each channel. The nonlinear photoelectric characteristic function is obtained based on the polynomial coefficients and polynomial functions of each channel.

[0009] Preferably, the measured color coordinates and measured luminance are converted into the current CIE 1931 XYZ tristimulus values ​​using the following formula (1): (1); in, , ,and This represents the current CIE 1931 XYZ tristimulus values; , These are the currently measured color coordinates. This is the current measured brightness value.

[0010] Preferably, obtaining the contribution rate per unit of pure luminous flux based on the current theoretical luminous flux and the current CIE 1931 XYZ tristimulus value includes: Based on the current CIE 1931 XYZ tristimulus value, the current theoretical luminous flux, and the hardware compensation coefficient, the contribution rate of unit pure luminous flux is obtained; The hardware compensation coefficient is a preset floating-point coefficient used to compensate for prediction errors caused by thermal crosstalk, light combining efficiency loss, and wavelength drift in the projector.

[0011] Preferably, the step of constructing a matrix using the unit pure luminous flux contribution rate and obtaining the ideal luminous flux of each of the red, green, and blue channels required to achieve the target CIE 1931 XYZ tristimulus value through matrix operations includes: Construct a 3×3 matrix M by arranging the unit pure luminous flux contribution rates of the red, green, and blue channels in columns; Establish a matrix equation based on the principle of color overlay. ; Matrix inversion operation The ideal luminous flux of each of the red, green, and blue channels is calculated. In this matrix, the first, second, and third columns of matrix M correspond to the unit pure luminous flux contribution rates of the red, green, and blue channels, respectively; L is a column vector composed of the ideal luminous fluxes of the red, green, and blue channels; and Target is the column vector of the target CIE 1931 XYZ tristimulus values.

[0012] Preferably, the step of performing a three-dimensional traversal search on the red channel current dimension, green channel current dimension, and blue channel current dimension within a preset number of steps, based on the restricted center point, to generate multiple discrete steps of current, includes: Using the red channel current value, green channel current value, and blue channel current value of the restricted center point as anchors, nested loop traversals are performed for the red channel current dimension, green channel current dimension, and blue channel current dimension, respectively: The first loop iterates through the red channel current values ​​within the preset red channel current search range at intervals of the current adjustment step size. The second loop iterates through the green channel current values ​​at intervals of the current adjustment step size within the preset green channel current search range for each red channel current value in the first loop. In the third loop, under each red-green current combination of the second loop, the blue channel current value is traversed within the preset blue channel current search range at intervals of the current adjustment step size; each third loop generates a set of step current combinations consisting of red channel current value, green channel current value and blue channel current value.

[0013] Preferably, the step of filtering the predicted color coordinates and predicted brightness of each combination to obtain the optimal predicted color coordinates and predicted brightness, and outputting the optimal drive current configuration value corresponding to the optimal predicted color coordinates and predicted brightness, includes: Remove combinations whose predicted brightness is lower than the minimum brightness specification from the combinations; In the remaining combinations, the Euclidean distance between the predicted color coordinates and the target color coordinates of each combination is calculated as the color difference; Sort the color differences from smallest to largest. When the color differences of multiple combinations are all within the preset tolerance range, select the combination with the largest predicted brightness as the optimal predicted color coordinate and predicted brightness, and use the driving current configuration value corresponding to this combination as the optimal driving current configuration value.

[0014] Preferably, the drive current configuration value is an integer value that can be set in the projector software, and there is a fixed linear mapping relationship between the drive current configuration value and the actual drive current; The independent variable x in the nonlinear photoelectric characteristic function is the driving current configuration value. The correction method performs calculations based on the driving current configuration value and converts the final output optimal driving current configuration value into a hexadecimal value and writes it into the hardware configuration register of the projector.

[0015] Preferably, before the steps of obtaining the measured color coordinates and measured brightness of the projector white field under the current drive current configuration value, the method further includes: The polynomial coefficients of the pre-fitted nonlinear photoelectric characteristic function and the hardware safety current boundary of each channel are stored in the calculation control module that executes the correction method. When calibrating each projector of the same model, the stored polynomial coefficients and the hardware safety current boundary are loaded.

[0016] Secondly, embodiments of this application provide a nonlinear step correction system for projector white balance, comprising: The measurement conversion module is used to obtain the current measured color coordinates and current measured brightness of the projector white field under the current driving current configuration value, and convert the current measured color coordinates and current measured brightness into the current CIE 1931 XYZ tristimulus values, and to obtain the current theoretical luminous flux corresponding to the current driving current configuration value; the current theoretical luminous flux is calculated by substituting the current driving current configuration value into a preset nonlinear photoelectric characteristic function; The contribution rate calculation module is used to obtain the contribution rate per unit of pure luminous flux based on the current luminous flux and the current CIE 1931 XYZ tristimulus value. The target determination module is used to determine the target CIE 1931 XYZ tristimulus value based on the preset target color coordinates and minimum brightness specification; The matrix operation module is used to construct a matrix using the unit pure luminous flux contribution rate, and to obtain the ideal luminous flux of the red, green and blue channels required to achieve the target CIE 1931 XYZ tristimulus value through matrix operations; The current derivation module is used to obtain the theoretical driving current configuration value of each channel based on the nonlinear photoelectric characteristic function and the ideal luminous flux of each channel. A boundary clamping module is used to limit the theoretical drive current configuration value of each channel within a preset hardware safety current boundary, forming a restricted center point; The three-dimensional search module is used to perform a three-dimensional traversal search of the three current dimensions of the red channel, green channel, and blue channel within a preset number of steps, based on the restricted center point, to generate multiple discrete steps of current combination; wherein each current value in the steps of current combination is an integer multiple of the current adjustment step size supported by the projector hardware. The data prediction module is used to obtain the predicted color coordinates and predicted brightness of each combination based on the multiple discrete step current combinations and the nonlinear photoelectric characteristic function. The filtering output module is used to filter the predicted color coordinates and predicted brightness of each combination, obtain the optimal predicted color coordinates and predicted brightness, and output the optimal drive current configuration value corresponding to the optimal predicted color coordinates and predicted brightness. The calibration execution module is used to calibrate the projector based on the optimal drive current configuration value.

[0017] Compared with the solutions of the prior art, the present invention has at least the following beneficial effects: (1) By using a high-order polynomial function to nonlinearly model the current-brightness relationship of the light source, the nonlinear photoelectric characteristics such as light saturation and thermal decay are accurately characterized by polynomials, replacing the unrealistic linear assumptions in the existing scheme, and fundamentally avoiding the problem of linear algorithms failing in the high current range. (2) The absolute luminous flux requirements of the red, green and blue channels are decoupled by matrix inversion in the CIE 1931 XYZ three-dimensional color space. The matrix is ​​constructed by dividing the measured XYZ tristimulus values ​​by the polynomial theoretical luminous flux to obtain the unit pure luminous flux contribution rate. Before matrix inversion, the interference of nonlinear light decay on color superposition relationship is effectively removed. (3) By introducing an optimization mechanism that combines constrained center point and discrete grid step search, the theoretical current obtained by matrix operation is first clamped within the hardware safety boundary to form a constrained center point. Then, using this as an anchor point, a three-dimensional traversal search is performed according to the physical step size supported by the hardware to ensure that each output current value is an integer multiple of the step size, thus solving the contradiction between continuous theoretical values ​​and discrete hardware step size. (4) By using the condition that the predicted brightness is not lower than the minimum brightness specification as a hard gate condition during the traversal optimization process, and then using the Euclidean distance between the predicted color coordinates and the target color coordinates as the evaluation index to sort and prioritize the solution with the highest brightness, the limitation of the existing scheme relying solely on color difference for sorting is broken, and the technical problem of color accuracy and brightness being mutually exclusive is fundamentally solved. (5) By introducing a hardware compensation coefficient to correct the calculation of the unit contribution rate, the systematic deviation between theory and practice caused by factors such as thermal crosstalk, light combining efficiency loss and wavelength drift is compensated, thereby improving the universality and robustness of the correction method.

[0018] In summary, this application organically combines key technologies such as high-order nonlinear polynomial modeling, CIE 1931 XYZ space matrix decoupling, three-dimensional discrete grid step search with constrained center points, and minimum brightness hard-gated multi-objective scoring to form a complete nonlinear step correction scheme for projector white balance. This scheme maximizes output brightness while ensuring the accuracy of white field color coordinates, significantly improving the optical quality and production yield of projector products. Attached Figure Description

[0019] Exemplary embodiments of the present invention can be more fully understood by referring to the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain the present invention and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0020] Figure 1 A flowchart illustrating a nonlinear step correction method for projector white balance, provided as an exemplary embodiment of this application; Figure 2 A schematic diagram of the structure of a nonlinear step correction system for projector white balance provided as an exemplary embodiment of this application; Figure 3A schematic diagram of the overall hardware architecture of a projector white balance calibration system provided for an exemplary embodiment of this application; Figure 4 A schematic diagram of an electronic device provided for an exemplary embodiment of this application; Figure 5 This is a schematic diagram of a computer-readable medium provided for an exemplary embodiment of this application. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] The following detailed explanation uses the factory white balance calibration of a certain projector model as an example. This projector uses red, green, and blue laser light sources (the laser light source in this embodiment is only an example; in practice, it can be various light sources such as LED or fluorescent light sources, and this application does not impose specific limitations). The drive current is set through a configuration value. It is important to note that the "drive current configuration value" operated on in this embodiment is an integer value that can be directly set in the projector software (e.g., 920, 900, 860, etc.), and there is a fixed linear mapping relationship between it and the actual drive current (in milliamperes). In actual software, only the current configuration value can be set and converted into the corresponding hexadecimal value before being written to the hardware configuration register; the actual current magnitude cannot be directly set. Therefore, this calibration method is based entirely on the drive current configuration value, and the final optimal drive current configuration value must also be converted to hexadecimal format before being written to the projector's configuration storage chip. The hardware supports a current adjustment step size of 10 units. The calibration target is white field color coordinates (x / y) = (0.29, 0.31), the minimum brightness specification is not less than 500 lumens, and the color coordinate tolerance range is ±0.015.

[0025] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a nonlinear step correction method for projector white balance according to an exemplary embodiment of this application. The method implemented in this disclosure is executed by a processor deployed in a computing control module.

[0026] Before performing the calibration process, it is necessary to pre-establish nonlinear photoelectric characteristic functions corresponding to the red, green, and blue light sources of the projector. These functions are used to characterize the nonlinear mapping relationship between the drive current configuration value and the output brightness of the light source. The specific process for establishing these functions is as follows: Before initiating the calibration process, multiple qualified prototypes of the same model were selected as test samples, and brightness data of each monochrome channel was collected under different drive current configuration values. The specific testing method was as follows: starting from the preset minimum current configuration value for each channel, the value was gradually increased in fixed steps of 10 configuration units to the preset maximum current configuration value. At each current configuration value, the red, green, and blue monochrome channels were individually illuminated using optical testing equipment such as a colorimeter and luminance meter, and the corresponding output brightness data was collected. Based on the collected batch of measured data, a fourth-order polynomial function was used... As a fitting model, the current configuration values ​​for each channel are determined using the least squares method. With predicted brightness The mapping relationship between them was fitted using least-squares to obtain the polynomial coefficients for each of the red, green, and blue channels. For the projector model used in this embodiment, the fitted nonlinear photoelectric characteristic functions for each channel are as follows: ; ; ; It should be noted that the variables in the above formula... The drive current configuration value is configurable by the software, not the actual operating current of the hardware, and is perfectly matched to the actual control logic of the device. The coefficients of each order in the formula (such as 29.44, -3.3311, 2.9516, -0.0866, -6E-08, etc.) are all calculated by substituting measured sample data into a fourth-order polynomial fitting algorithm. Although the coefficient values ​​have decimal places or extremely small values, they will not change the overall curve shape of the photoelectric characteristics of the light source. The fitting results have extremely high accuracy and universality, and can be accurately adapted to all mass-produced equipment of the same model.

[0027] This embodiment uses a fourth-order polynomial for fitting, which balances fitting accuracy and algorithm complexity across the entire current configuration range, accurately covering the nonlinear photoelectric characteristics of the light source throughout its entire operating range, including the linear emission region and the saturated emission region. In other embodiments, third-order or fifth-order polynomials can be flexibly selected for fitting based on the nonlinear characteristics of different light sources. Furthermore, the overall structure, heat dissipation scheme, and light source configuration of the same projector model are completely identical. The typical sample data used in this fitting can represent the photoelectric characteristics of the entire batch of products. Therefore, after product finalization, the polynomial coefficients can be permanently stored, eliminating the need for repeated fitting for each device to be calibrated. Only when the product hardware iterates, such as changes in the light source model, heat dissipation structure, or optical path design, is it necessary to re-collect data and update the polynomial coefficients. This design greatly simplifies the production line calibration process and effectively improves batch calibration efficiency.

[0028] In addition, the hardware safety current configuration boundary ranges for the red, green, and blue channels need to be configured in advance according to the projector's hardware design parameters. The maximum boundary value is the maximum current configuration value that the hardware can withstand, representing an insurmountable hard safety threshold; the minimum boundary value is used to avoid insufficient overall brightness due to excessively low current configuration values. In this embodiment, the specific safety configuration ranges for each channel are: red channel [825, 970], green channel [840, 950], and blue channel [800, 910]. These safety boundary ranges can be adjusted synchronously during hardware parameter iteration updates. During mass production calibration, the processor directly loads the pre-stored polynomial coefficients and hardware safety boundary parameters, eliminating the need for reconfiguration on a per-device basis, thus adapting to batch automated production scenarios.

[0029] After completing the above-mentioned pre-configuration parameters and model building, perform the following automated calibration steps for each projector to be calibrated: S100: Obtain the current measured color coordinates and current measured brightness of the projector white field under the current driving current configuration value, and convert the current measured color coordinates and current measured brightness into the current CIE 1931 XYZ tristimulus values ​​(in the standard colorimetric system established by the International Commission on Illumination (CIE) in 1931, the stimulus values ​​of three theoretical virtual primary colors (X, Y, Z) required to match any color of light, where Y directly represents brightness, and X and Z only characterize chromaticity), and obtain the current theoretical luminous flux corresponding to the current driving current configuration value; the current theoretical luminous flux is calculated by substituting the current driving current configuration value into a preset nonlinear photoelectric characteristic function; Specifically, in the CIE 1931 standard colorimetric system, X, Y, and Z are three sets of theoretical stimulus quantities that match the color of visible light. The Y component directly corresponds to optical brightness, while the X and Z components are used to characterize colorimetric information. The current theoretical luminous flux is calculated by substituting the real-time drive current configuration value into the preset channel nonlinear photoelectric characteristic function.

[0030] Specifically, the projector is controlled to output a standard white field image with the current default drive current configuration (e.g., R=920, G=900, B=860). The white field optical parameters are collected by optical detection equipment such as a colorimeter and spectrometer to obtain the current measured color coordinates of the white field. Compared with the measured brightness The measured monochrome red channel color coordinates in this embodiment are: (0.7248, 0.2722), green channel color coordinates (0.1221, 0.8411), and blue channel color coordinates (0.1395, 0.0314). The current measured white point value... .

[0031] Based on the CIE 1931 standard colorimetric conversion principle, the measured color coordinates and luminance are converted into the current CIE 1931 XYZ tristimulus values ​​using the following formula (1): (1); It should be noted that in colorimetry... The component is directly equal to the brightness value. This is a strict requirement of the CIE 1931 colorimetric formula, and and The components are based on , and The mathematical relationship is indirectly derived from this. Substituting the above measured data, we get: , , Therefore, the current CIE 1931 XYZ tristimulus values ​​for the white field are (524.4, 580.6, 767.9).

[0032] Simultaneously, the current drive current configuration values ​​R=920, G=900, and B=860 are substituted into the pre-established three-channel polynomial function. , , The theoretical luminous flux of the red channel was calculated. The current theoretical luminous flux of the green channel The current theoretical luminous flux of the blue channel The theoretical luminous flux reflects the brightness value that each channel should produce under the current drive current configuration, as predicted by the nonlinear model. The above parameters are the standard luminous brightness of each channel predicted by the nonlinear model, which are used to eliminate hardware nonlinearity errors in the subsequent process.

[0033] S110, based on the current theoretical luminous flux and the current CIE 1931 XYZ tristimulus value, obtains the contribution rate of unit pure luminous flux; Specifically, each channel has a preset hardware compensation coefficient. (The default initial value is 1.0, which can be adaptively fine-tuned according to the product's optical characteristics. Example parameter) , , The formula for calculating the contribution rate per unit of pure luminous flux is: (2); in, This represents the contribution rate of pure luminous flux per unit of the corresponding channel. The measured tristimulus values ​​for the channel. This represents the theoretical luminous flux of the channel. Channel hardware compensation coefficient.

[0034] The measured XYZ tristimulus values ​​are the combined chromaticity and luminance feedback data of the actual emission from the device, while the theoretical luminous flux is the predicted luminance data from an ideal nonlinear model. Calculating the ratio of these two values ​​effectively eliminates measurement errors caused by laser source decay and nonlinear emission characteristics, yielding a pure photoelectric conversion coefficient unaffected by hardware nonlinearity. This provides data support for subsequent accurate calculation of the luminous flux ratio. Specifically, the measured total XYZ value is divided by the theoretical luminous flux derived from the polynomial (and combined with the hardware compensation coefficient). (After correction), the interference of nonlinear light decay of the laser source on color measurement data can be effectively eliminated. Specifically, the measured XYZ values ​​obtained in the aforementioned steps are based on actual measurements. The total tristimulus value is calculated, while the theoretical luminous flux here is based on a nonlinear polynomial. Dividing the calculated brightness value by the overall value eliminates complex nonlinear light decay factors, resulting in a pure photoelectric conversion coefficient free from the influence of nonlinear factors. Using this pure unit contribution rate to perform subsequent matrix inversion operations yields a physically accurate proportion of luminous flux for each channel.

[0035] At the same time, theoretical mathematical formulas often cannot perfectly fit real physical scenarios. When the result is exactly as predicted, it indicates that the calculated result is very close to the actual result, approaching perfection. However, in actual projectors, there are issues such as thermal crosstalk between red, green, and blue light (interactions caused by heat generation from different laser channels), light combining efficiency loss, transient changes in electrical parameters, and wavelength drift. These issues can all affect the test results, leading to a systematic deviation between the polynomial prediction and the actual measurement. Using a compensation coefficient can effectively compensate for this deviation. The compensation coefficient is a continuous floating-point coefficient, and its working principle is as follows: If... Get smaller ( If the calculated unit contribution rate increases, the algorithm will consider the channel to have extremely high luminous efficiency, and therefore allocate less current to it in the final derivation; if Get bigger ( The algorithm will consider the channel to have low luminous efficiency and allocate more current to it. The compensation coefficient is set and adjusted according to the optical shape of the product itself, and is not a fixed value. It can be iteratively optimized based on feedback from actual correction results. When a batch of projectors of the same model show a persistent red / blue tint in color coordinates, the hardware compensation coefficient of the corresponding channel can be decreased / increased accordingly. Complete batch deviation correction.

[0036] S120, determine the target CIE 1931 XYZ tristimulus value based on the preset target color coordinates and minimum brightness specification; Specifically, the target color coordinates are preset specifications for white balance correction. The purpose of white balance correction is to adjust the projector's white point color coordinates to this target value. Therefore, the target color coordinates are known parameters, not calculated. For example, the target color coordinates in this embodiment are... The minimum brightness specification is Lumens. The target CIE 1931 XYZ tristimulus values ​​are calculated using formula (1): Therefore, the target tristimulus value is obtained. .

[0037] S130 uses the unit pure luminous flux contribution rate to construct a matrix, and obtains the ideal luminous flux of the red, green and blue channels required to achieve the target CIE1931 XYZ tristimulus value through matrix operations; Specifically, the unit pure luminous flux contribution rates of the red, green, and blue channels obtained in step S110 are used to construct a 3×3 matrix based on the color superposition principle in colorimetry, where the white field color is formed by mixing and superimposing red, green, and blue light according to their respective luminous fluxes. .matrix The first column represents the unit XYZ contribution rate of the red channel, the second column represents the unit XYZ contribution rate of the green channel, and the third column represents the unit XYZ contribution rate of the blue channel. (3); According to the principle of color superposition, the tristimulus value of the target white field is equal to the unit contribution rate of the red, green, and blue channels multiplied by their respective luminous flux. The sum of these can be expressed as a linear algebraic matrix equation: (4); in, Let be the column vector of the ideal luminous flux for each channel to be solved. This is the column vector of target tristimulus values ​​determined in step S120. It should be noted that in this formula... The symbol indicates matrix multiplication, not basic scalar addition, subtraction, multiplication, and division. Given... and ,beg Then, through the inverse operation of the matrix... Calculate the ideal luminous flux for each of the red, green, and blue channels. , and .

[0038] This solution performs matrix decoupling operations in the three-dimensional XYZ chromaticity space. Compared with the traditional two-dimensional chromaticity coordinate ratio extrapolation method, it can completely avoid nonlinear interpolation errors and significantly improve the accuracy of luminous flux ratio.

[0039] S140, based on the nonlinear photoelectric characteristic function and the ideal luminous flux of each channel, obtains the theoretical driving current configuration value of each channel; Specifically, the ideal luminous flux of the red channel is calculated by inverting the aforementioned matrix. Substitution In the reverse calculation, the theoretical drive current configuration value of the red channel is derived; similarly, from... Combination The theoretical drive current configuration value for the green channel is obtained from... Combination The theoretical drive current configuration value for the blue channel was obtained. Then, the pure unit contribution rate, obtained after eliminating nonlinear interference, was transformed into the specific executable drive current configuration value for each channel through matrix decoupling and matrix inverse operation, completing the full mapping from optical target to electrical parameters.

[0040] S150 limits the theoretical drive current configuration value of each channel within the preset hardware safety current boundary, forming a restricted center point; Specifically, the theoretical drive current configuration values ​​for each channel are compared with the hardware safety current boundary of that channel. The maximum value of the hardware safety current boundary is determined by the projector hardware design and is a hard constraint that must not be exceeded (e.g., the maximum value of 970 for the red channel corresponds to the actual upper limit of current). The minimum value can prevent the calculated brightness from being too low and failing to meet the desired brightness specifications (e.g., the minimum value of 825 for the red channel corresponds to the lower limit of current to ensure minimum brightness). If the theoretical value is greater than the maximum value, it is forcibly clamped to the maximum value; if the theoretical value is less than the minimum value, it is forcibly clamped to the minimum value. The current combination formed within the safety boundary after clamping is, for example... These are the restricted center points. If the hardware is changed or a new product is developed, these boundary values ​​will change accordingly.

[0041] S160, with the restricted center point as the reference, performs a three-dimensional traversal search of the three current dimensions of the red channel, green channel and blue channel within a preset number of steps to generate multiple sets of discrete step current combinations; where each current value in the step current combination is an integer multiple of the current adjustment step size supported by the projector hardware. In this embodiment, the three-dimensional traversal search refers to the process of constructing a three-dimensional search grid along the three current dimensions (red, green, and blue), using a restricted center point as the anchor point and following a physical step size supported by the hardware (e.g., step size = 10 units), and exhaustively calculating every intersection point in the grid. The following will illustrate this using typical search parameters as an example: Assume the current at the confined center point is , , The current adjustment step size is 10 units, and the preset step range is ±50 steps (i.e., the search radius is 50 steps), combined with the hardware safety boundary of each channel (red channel search boundary). Green channel search boundary Blue channel search boundary ), execute the following three nested loops for traversal: First loop (red channel current dimension): The red channel current starts from 870 and increases to 970 in increments of 10, traversing the red channel current value; Second loop (green channel current dimension): Under each red channel current value in the first loop, the green channel current starts from 850 and increases to 950 in steps of 10, traversing the green channel current value. The third loop (blue channel current dimension): Under each red-green current combination in the second loop, the blue channel current starts from 810 and increases to 910 in steps of 10, traversing the blue channel current value; each third loop generates a set of step current combinations consisting of red channel current value, green channel current value and blue channel current value.

[0042] Through the aforementioned three nested loops, a set of current combination points corresponding to the intersections of all discrete grids is ultimately formed, for example: (920,900,860), (920,900,870), (920,910,860), (920,920,860), (910,900,870)... and so on. Since the loop step size is the smallest adjustment unit supported by the hardware (10 units), each generated current value is naturally an integer multiple of the step size and can be directly converted to hexadecimal values ​​and written into the projector's hardware configuration register for execution, without any additional approximation, rounding, or interpolation processing. This is something that existing linear correction schemes cannot achieve at all.

[0043] S170, based on multiple discrete combinations of step currents and the nonlinear photoelectric characteristic function, obtain the predicted color coordinates and predicted brightness corresponding to each combination; Specifically, each group generated by the aforementioned steps The current combinations are substituted into the three-channel polynomial function pre-established in step one. , and The luminance value of each channel under the corresponding current is predicted. Then, combined with the unit pure luminous flux contribution rate of each channel obtained in step S110, the total predicted XYZ tristimulus value is calculated by summing the predicted luminance of each channel multiplied by the corresponding XYZ contribution rate using the color superposition principle. Finally, the total predicted XYZ tristimulus value is converted into predicted color coordinates using the CIE 1931 colorimetric formula. and predicted brightness .

[0044] S180: Filter the predicted color coordinates and predicted brightness of each combination to obtain the optimal predicted color coordinates and predicted brightness, and output the optimal drive current configuration value corresponding to the optimal predicted color coordinates and predicted brightness. Specifically, this implementation adopts a progressive screening strategy of first using hard constraint filtering and then multi-objective scoring, including the following steps: The first step is hard-gated brightness screening: from all combinations obtained in the previous steps, the predicted brightness is directly eliminated. Current combinations that are 500 lumens below the minimum brightness specification. This hard-gating condition is a veto mechanism, meaning that combinations that do not meet the brightness requirement will not be considered regardless of their color coordinate accuracy. The second step is color difference calculation and sorting: among the remaining combinations that have passed the brightness screening, calculate the predicted color coordinates and target color coordinates for each group. The Euclidean distance between them is used as the color difference, according to the color difference Sort all remaining combinations from smallest to largest; among them, color difference It is calculated using the following formula (5): (5); The third step is to prioritize brightness: when the color difference of multiple combinations is within the preset tolerance range ( When considering combinations that minimize color difference, instead of simply selecting the combination with the smallest color difference, a brightness-first strategy is adopted. That is, among all combinations that satisfy the color difference tolerance, the predicted brightness is selected. The combination with the largest color difference is taken as the optimal solution. This comprehensive scoring strategy, which maximizes brightness after achieving the color difference standard, fundamentally solves the problem of the inability to achieve both color accuracy and brightness in traditional solutions. Step 4: Output the optimal solution: Output the drive current configuration value corresponding to the obtained optimal solution. .

[0045] S190, The projector is calibrated based on the optimal drive current configuration value.

[0046] Specifically, the drive current configuration value The data is converted to hexadecimal format and written to the configuration storage chip of the projector to be calibrated to complete the white balance correction. After calibration, the projector will drive the red, green, and blue laser light sources with the optimal current configuration value, and the projected white field image will simultaneously meet the comprehensive requirements of target color coordinate accuracy and maximum brightness.

[0047] In some preferred embodiments, after calibration, the system can also generate the five configurations with the smallest color differences and their corresponding predicted data (covering current combinations and predicted color coordinates). Predicted brightness and color difference The output is sent to the user interface for operators to manually confirm and select based on production priorities (such as prioritizing brightness or prioritizing color accuracy).

[0048] It should be noted that the data flow logic between each step in this embodiment is clear and tightly connected: Step S100 simultaneously acquires the measured XYZ and theoretical luminous flux, which serve as the common input for S110; the unit purity contribution rate output by S110, after being incorporated by the target XYZ in S120, is input into S130 for matrix decoupling; the ideal luminous flux in S130 is converted into theoretical current through inverse operation in S140; S150 applies boundary clamping to the theoretical current to form a restricted center point; S160 uses the restricted center point as an anchor point to perform a three-dimensional discrete search; S170 performs polynomial prediction on the discrete combination generated by the search; S180 performs multi-objective scoring and filtering on the prediction results using "brightness hard gating, color difference sorting, and brightness priority" and outputs the results; S190 completes correction based on the optimal solution. The entire data link extends from front-end optical measurement to back-end hardware configuration writing, forming an inseparable and complete technical closed loop. The entire process, from optical data acquisition, nonlinear error elimination, precise matrix calculation, parameter boundary constraints, 3D mesh search, data prediction and analysis to optimal parameter solidification and writing, forms a complete automated correction technology system. It is logically rigorous, highly implementable, and suitable for industrial mass production scenarios.

[0049] Please refer to Figure 2 , Figure 2 This is a schematic diagram of a nonlinear step correction system 20 for projector white balance provided in an exemplary embodiment of this application. This embodiment further illustrates the method in the foregoing embodiments in conjunction with the system architecture.

[0050] Please refer to Figure 3 The calibration system 20 provided in this application embodiment includes, at the physical hardware level, a projection module 31 to be calibrated, a color measurement device 32, and a computer control and calculation module 33. The projection module 31 to be calibrated is the projector or optical engine to be subjected to white balance calibration, used to project RGBW white field light; the color measurement device 32 is an optical detection device such as a colorimeter, spectrometer, or imaging colorimeter, used to collect color information such as color coordinates and brightness of the projected image and output it to the computer control and calculation module 33; the computer control and calculation module 33 is an industrial control computer, embedded terminal, or host computer equipped with a calibration algorithm program, used to receive color information and perform nonlinear step correction calculations, and finally generate the optimal drive current configuration and write it into the configuration register of the projection module to be calibrated, completing the hardware calibration closed loop.

[0051] Among them, the color measurement device 32 corresponds to the measurement conversion module 210 in the functional modules below; the computer control and calculation module 33 integrates all calculation and processing functions such as contribution rate calculation, target determination, matrix operation, current derivation, boundary clamping, three-dimensional search, data prediction, and filtering output; the projection module to be calibrated 31 corresponds to the calibration execution module, and the three complete data interaction and command issuance through the communication bus.

[0052] Specifically, the system 20 includes the following modules: measurement conversion module 200, contribution rate calculation module 210, target determination module 220, matrix operation module 230, current derivation module 240, boundary clamping module 250, three-dimensional search module 260, data prediction module 270, filtering output module 280, and correction execution module 290.

[0053] Specifically, the measurement conversion module 200 can be an optical measurement device such as a colorimeter, spectrometer or imaging colorimeter, used to obtain the current measured color coordinates and current measured brightness of the projector white field under the current driving current configuration value, and convert the measured color coordinates and brightness into the current CIE 1931 XYZ tristimulus values ​​according to formula (1) and output them to the contribution rate calculation module 210.

[0054] Specifically, the contribution rate calculation module 210, target determination module 220, matrix operation module 230, current derivation module 240, boundary clamping module 250, three-dimensional search module 260, data prediction module 270, filtering output module 280, and correction execution module 290 form a complete calculation and control module. These modules are communicatively connected to the measurement conversion module 200 and the projection device to be calibrated (communication interfaces can be USB, RS232, WiFi, or Ethernet, etc.). Internally, each module includes a processor and a memory. The memory stores pre-fitted polynomial coefficients of the nonlinear photoelectric characteristic functions of each channel, hardware safety current boundary parameters for each channel, and a computer program that can run on the processor. When the processor executes the computer program, it implements all the computational processing logic of steps S100 to S190 in Embodiment 1, specifically including: receiving the current CIE1931 XYZ tristimulus value output by the measurement conversion module 200 and obtaining the current theoretical luminous flux; calculating the contribution rate of unit pure luminous flux; determining the target tristimulus value; performing matrix inversion decoupling and inverse operation to derive the theoretical current; performing hardware boundary clamping and three-dimensional discrete mesh traversal search; performing combined prediction based on nonlinear functions; and performing multi-objective scoring of luminance hard-gating screening, color difference sorting, and luminance priority selection. Finally, the processor converts the selected optimal drive current configuration value into hexadecimal format and writes it into the configuration storage chip of the projection device to be calibrated through the communication interface, realizing a fully automatic calibration closed loop.

[0055] Specifically, during the calibration process, the projection device projects white light according to preset parameters, and after calibration, it drives the red, green, and blue light sources according to the written optimal current configuration values. The entire system operates fully automatically during the calibration process, from the measurement conversion module 200 acquiring optical data to the calculation and control module completing the algorithm calculation and writing back the configuration parameters. The complete calibration time for a single device can be controlled within tens of seconds, which facilitates large-scale, high-efficiency automated deployment on projector production lines.

[0056] It should be noted that the system in this application adopts a design logic that corresponds one-to-one between method steps and functional modules. Each algorithm step is supported by a corresponding hardware / software module. The technical logic is complete and the hierarchy is clear, making it fully adaptable to industrial mass production calibration scenarios. At the same time, it reserves space for parameter iteration, making it compatible with projector products of different models and hardware parameters. It has strong versatility and scalability.

[0057] It should be understood that the above division of modules is only a logical functional division. In actual implementation, the functions of multiple modules can be integrated into the same processing unit, or the function of one module can be split into multiple sub-modules. The embodiments of this application do not limit the specific implementation method of each module.

[0058] Please refer to Figure 4 This illustrates a schematic diagram of an electronic device provided by some embodiments of this application. For example... Figure 4 As shown, the electronic device 40 includes: a processor 400, a memory 401, a bus 402, and a communication interface 403. The processor 400, the communication interface 403, and the memory 401 are connected via the bus 402. The memory 401 stores a computer program that can run on the processor 400. When the processor 400 runs the computer program, it executes the method described above in this application.

[0059] The memory 401 may include high-speed random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface 403 (which can be wired or wireless), such as the Internet, wide area network, local area network, or metropolitan area network.

[0060] Bus 402 can be an ISA bus, PCI bus, or EISA bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. The memory 401 is used to store programs. After receiving an execution instruction, the processor 400 executes the program. The methods disclosed in any of the foregoing embodiments of this application can be applied to the processor 400, or implemented by the processor 400.

[0061] The processor 400 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the hardware of the processor 400 or by instructions in software form. The processor 400 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules may reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory 401. The processor 400 reads the information in memory 401 and, in conjunction with its hardware, completes the steps of the above method.

[0062] The electronic devices provided in the embodiments of this application and the methods provided in the embodiments of this application are based on the same inventive concept and have the same beneficial effects as the methods they adopt, operate, or implement. The electronic devices provided in the embodiments of this application can be intelligent devices with data processing and hardware read / write capabilities, such as projector-built-in main control chips, production line calibration industrial control computers, and embedded calibration terminals, and can be independently deployed to complete the white balance calibration of projectors.

[0063] This application also provides a computer-readable medium corresponding to the method provided in the foregoing embodiments. Please refer to... Figure 4 The computer-readable storage medium shown is an optical disc 50 on which a computer program (i.e., a program product) is stored, which, when run by a processor, performs the aforementioned method.

[0064] The computer-readable storage medium may include, but is not limited to, various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks. In a specific application scenario, the computer-readable storage medium may be built into the projector calibration terminal as part of the firmware; or it may be deployed as a standalone software product in the production line calibration equipment through download or physical distribution, enabling conventional calibration hardware to acquire the core function of nonlinear step white balance calibration as described in this application after loading the program.

[0065] The computer-readable storage medium provided in the above embodiments of this application and the method provided in the embodiments of this application are based on the same inventive concept and have the same beneficial effects as the methods adopted, run or implemented by the applications stored therein.

[0066] This embodiment also provides a computer program product, which includes a computer program. When executed by a processor, the computer program implements the methods described in any of the above embodiments.

[0067] The computer program product may include any combination of one or more program modules, which can be deployed on production line industrial control terminals, projector built-in control systems, or cloud calibration service platforms. It can provide localized algorithm support for batch projector calibration, or be packaged as a software development kit (SDK) to adapt to the production calibration system of various smart projection devices. It can achieve high-precision and high-efficiency white balance nonlinear calibration without significantly modifying the original equipment architecture.

[0068] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0069] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0070] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and there may be other division methods in actual implementation. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the coupling or direct coupling or communication connection shown or discussed may be through some communication interface; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0071] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0072] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application.

Claims

1. A nonlinear step correction method for projector white balance, characterized in that, Includes the following steps: Obtain the current measured color coordinates and current measured brightness of the projector white field under the current driving current configuration value, and convert the current measured color coordinates and current measured brightness into the current CIE 1931 XYZ tristimulus values, and obtain the current theoretical luminous flux corresponding to the current driving current configuration value; The current theoretical luminous flux is calculated by substituting the current driving current configuration value into a preset nonlinear photoelectric characteristic function; Based on the current theoretical luminous flux and the current CIE 1931 XYZ tristimulus value, the contribution rate per unit of pure luminous flux is obtained; The target CIE 1931 XYZ tristimulus values ​​are determined based on the preset target color coordinates and minimum brightness specifications. A matrix is ​​constructed using the unit pure luminous flux contribution rate, and the ideal luminous flux of the red, green, and blue channels required to achieve the target CIE 1931XYZ tristimulus value is obtained through matrix operations. Based on the aforementioned nonlinear photoelectric characteristic function and the ideal luminous flux of each channel, the theoretical driving current configuration value for each channel is obtained. The theoretical drive current configuration value of each channel is limited within a preset hardware safety current boundary, forming a restricted center point; Using the restricted center point as a reference, a three-dimensional traversal search is performed on the three current dimensions of the red channel, green channel, and blue channel within a preset number of steps to generate multiple discrete step current combinations; wherein each current value in the step current combination is an integer multiple of the current adjustment step size supported by the projector hardware. Based on the multiple discrete combinations of step currents and the nonlinear photoelectric characteristic function, the predicted color coordinates and predicted brightness corresponding to each combination are obtained. The predicted color coordinates and predicted brightness of each combination are filtered to obtain the optimal predicted color coordinates and predicted brightness, and the optimal drive current configuration value corresponding to the optimal predicted color coordinates and predicted brightness is output. The projector is calibrated based on the optimal drive current configuration value.

2. The method according to claim 1, characterized in that, The nonlinear photoelectric characteristic function is pre-established in the following manner: Before the calibration process is executed, brightness test data of each channel of multiple prototypes of the same model under different drive current configuration values ​​are collected. The brightness test data is fitted with a polynomial function using least squares to obtain the polynomial coefficients of each channel. The nonlinear photoelectric characteristic function is obtained based on the polynomial coefficients and polynomial functions of each channel.

3. The method according to claim 1, characterized in that, The measured color coordinates and measured luminance are converted to the current CIE 1931 XYZ tristimulus values ​​using the following formula (1): （1）； in, , ,and This represents the current CIE 1931 XYZ tristimulus values; These are the currently measured color coordinates. This is the current measured brightness value.

4. The method according to claim 1, characterized in that, The method for obtaining the contribution rate per unit of pure luminous flux based on the current theoretical luminous flux and the current CIE 1931 XYZ tristimulus value includes: Based on the current CIE 1931 XYZ tristimulus value, the current theoretical luminous flux, and the hardware compensation coefficient, the contribution rate of unit pure luminous flux is obtained; The hardware compensation coefficient is a preset floating-point coefficient used to compensate for prediction errors caused by thermal crosstalk, light combining efficiency loss, and wavelength drift in the projector.

5. The method according to claim 1, characterized in that, The process of constructing a matrix using the unit pure luminous flux contribution rate and obtaining the ideal luminous flux of each of the red, green, and blue channels required to achieve the target CIE 1931 XYZ tristimulus value through matrix operations includes: Construct a 3×3 matrix M by arranging the unit pure luminous flux contribution rates of the red, green, and blue channels in columns; Establish a matrix equation based on the principle of color overlay. ; Matrix inversion operation The ideal luminous flux of each of the red, green, and blue channels is calculated. In this matrix, the first, second, and third columns of matrix M correspond to the unit pure luminous flux contribution rates of the red, green, and blue channels, respectively; L is a column vector composed of the ideal luminous fluxes of the red, green, and blue channels; and Target is the column vector of the target CIE 1931 XYZ tristimulus values.

6. The method according to claim 1, characterized in that, The process involves using the restricted center point as a reference, performing a three-dimensional traversal search within a preset number of steps on the red channel current dimension, green channel current dimension, and blue channel current dimension, respectively, to generate multiple discrete combinations of stepped currents, including: Using the red channel current value, green channel current value, and blue channel current value of the restricted center point as anchors, nested loop traversals are performed for the red channel current dimension, green channel current dimension, and blue channel current dimension, respectively: The first loop iterates through the red channel current values ​​within the preset red channel current search range at intervals of the current adjustment step size. The second loop iterates through the green channel current values ​​at intervals of the current adjustment step size within the preset green channel current search range for each red channel current value in the first loop. In the third loop, under each red-green current combination of the second loop, the blue channel current value is traversed within the preset blue channel current search range at intervals of the current adjustment step size; each third loop generates a set of step current combinations consisting of red channel current value, green channel current value and blue channel current value.

7. The method according to claim 1, characterized in that, The step of filtering the predicted color coordinates and predicted brightness of each combination to obtain the optimal predicted color coordinates and predicted brightness, and outputting the optimal drive current configuration value corresponding to the optimal predicted color coordinates and predicted brightness, includes: Remove combinations whose predicted brightness is lower than the minimum brightness specification from the combinations; In the remaining combinations, the Euclidean distance between the predicted color coordinates and the target color coordinates of each combination is calculated as the color difference; Sort the color differences from smallest to largest. When the color differences of multiple combinations are all within the preset tolerance range, select the combination with the largest predicted brightness as the optimal predicted color coordinate and predicted brightness, and use the driving current configuration value corresponding to this combination as the optimal driving current configuration value.

8. The method according to claim 1, characterized in that, The drive current configuration value is an integer value that can be set in the projector software, and there is a fixed linear mapping relationship between the drive current configuration value and the actual drive current. The independent variable x in the nonlinear photoelectric characteristic function is the driving current configuration value. The correction method performs calculations based on the driving current configuration value and converts the final output optimal driving current configuration value into a hexadecimal value and writes it into the hardware configuration register of the projector.

9. The method according to claim 1, characterized in that, Before the steps of obtaining the measured color coordinates and measured brightness of the projector white field under the current drive current configuration value, the method further includes: The polynomial coefficients of the pre-fitted nonlinear photoelectric characteristic function and the hardware safety current boundary of each channel are stored in the calculation control module that executes the correction method. When calibrating each projector of the same model, the stored polynomial coefficients and the hardware safety current boundary are loaded.

10. A nonlinear step correction system for projector white balance, characterized in that, include: The measurement conversion module is used to obtain the current measured color coordinates and current measured brightness of the projector white field under the current driving current configuration value, and convert the current measured color coordinates and current measured brightness into the current CIE 1931 XYZ tristimulus values, and obtain the current theoretical luminous flux corresponding to the current driving current configuration value; The current theoretical luminous flux is calculated by substituting the current driving current configuration value into a preset nonlinear photoelectric characteristic function; The contribution rate calculation module is used to obtain the contribution rate per unit of pure luminous flux based on the current theoretical luminous flux and the current CIE 1931 XYZ tristimulus value. The target determination module is used to determine the target CIE 1931 XYZ tristimulus value based on the preset target color coordinates and minimum brightness specification; The matrix operation module is used to construct a matrix using the unit pure luminous flux contribution rate, and to obtain the ideal luminous flux of the red, green and blue channels required to achieve the target CIE 1931 XYZ tristimulus value through matrix operations; The current derivation module is used to obtain the theoretical driving current configuration value of each channel based on the nonlinear photoelectric characteristic function and the ideal luminous flux of each channel. A boundary clamping module is used to limit the theoretical drive current configuration value of each channel within a preset hardware safety current boundary, forming a restricted center point; The three-dimensional search module is used to perform a three-dimensional traversal search of the three current dimensions of the red channel, green channel, and blue channel within a preset number of steps, based on the restricted center point, to generate multiple discrete steps of current combination; wherein each current value in the steps of current combination is an integer multiple of the current adjustment step size supported by the projector hardware. The data prediction module is used to obtain the predicted color coordinates and predicted brightness of each combination based on the multiple discrete step current combinations and the nonlinear photoelectric characteristic function. The filtering output module is used to filter the predicted color coordinates and predicted brightness of each combination, obtain the optimal predicted color coordinates and predicted brightness, and output the optimal drive current configuration value corresponding to the optimal predicted color coordinates and predicted brightness. The calibration execution module is used to calibrate the projector based on the optimal drive current configuration value.

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