Research On Pixel-level Accurate Acquisition And Calibration Technology Of Utra-high Density LED Display

The acquisition and calibration technology of LED display screen is to solve the phenomenon of "Mosaic" and "pitting" caused by the inconsistency of brightness and chroma between LED chips,which is one of the key technologies in LED display field.The existing acquisition and calibration method mainly acquire the red,green and blue primary colors of the display screen point by point by using the camera with the filter that conforms to the visual characteristics of human eyes to obtain the brightness information of each display pixel,so as to achieve the purpose of point-by-point correction.With the development of LED display technology,Mini-LED and Micro-LED have gradually become the mainstream.Ultra-high-definition displays such as 4K and 8K have attracted increasing attention.The huge number of pixels,tiny chip size and tiny pixel spacing make "Mosaic" and "pitting" more prominent and human eyes will also have a stronger ability to perceive the difference in brightness of adjacent pixels,which puts forward higher requirements on the accuracy of acquisition and correction.However existing acquisition and calibration methods are still in the application stage of large size and large pitch,the acquisition and calibration accuracy of Mini-LED and Micro-LED display cannot meet the needs of human eyes.So that the brightness difference between display pixels after calibration is still perceived.In order to improve the accuracy and precision of the acquisition and calibration,this dissertation studies in many aspects,establishing the optical error transfer model in the acquisition process based on the LED display light angle and the optical error of the acquisition equipment,and proposes an adaptive calibration method.Then a composite acquisition method of primary colors based on spectral mixing is proposed to improve the equivalent brightness of the three primary colors from the acquisition end.Finally,the mathematical model and color compensation model of the influence of the primary color lightness change on the display color offset trajectory are established based on the color change theory,achieving the accurate control of display color.The main work of this dissertation is as follows:1.The optical propagation error caused by the luminescence characteristics of the luminescent chip and the production process of LED display has been established,then the influence of the error on the acquisition accuracy has been analyzed.The optical error transmission model based on LED display and the acquisition process has been established.combining the analysis of the vignetting error of the acquisition equipment and the transmission characteristics of the error.The error factor of optical error transmission is analyzed,and an adaptive error calibration method is proposed to realize optical error calibration in the acquisition process to improve the acquisition accuracy.Finally,the accuracy of the modified acquisition is verified by experiments.2.The spectral response curve of the three primary colors of LED has been analyzed,and the intensity of brightness information received has been analyzed by the acquisition equipment by combining the spectral response function of the three primary colors and the spectral response function of X,Y and Z filters.Then the brightness loss of three primary colors by different filters is described in detail details.Based on the spectral mixing theory,a three-color composite acquisition method has been established,and the response curve of the mixed spectrum has been analyzed.Combining with the spectral response curve of X,Y and Z filters,the brightness enhancement of the mixed spectrum in the acquisition process has been described in detail.Finally,the linear transformation of the mixed spectrum is used to obtain the brightness information of the single spectrum,which improves the acquisition accuracy.The accuracy of the modified acquisition is verified by experiments.3.The relationship model between the brightness variation of LED display three primary colors and the color offset track and the color compensation model has been established.To change the brightness of the display of the single primary color and more primary colors to display color brightness and chroma has been analyzed.The influence of influence factors in the model are detailed,and the inverse transformation of the model has been deduced according to the characteristics of the influence factors,making the brightness of the three primary colors change and display color migration path constitutes the mapping relationship between each other.Finally,color precision compensation of display brightness adjustment has been realized.4.The relationship model and color compensation model between the brightness and chroma of LED display and the color offset track has been established.Six chromaticity calibration factors have been introduced to analyze the influence of chromaticity calibration factors on the display gamut of the three primary colors,constructing the mixed primary colors with positive chromaticity factors.Meanwhile,the influence of brightness change of mixed primary color on display color has been analyzed in detail,and the accurate color compensation after chromaticity calibration has been realized.In this dissertation,through a lot of theoretical analysis and engineering practice,solving the problem of ultra-high density,ultra-small spacing,ultra-large size LED display accurate acquisition and correction.The display effect is guaranteed to a great extent and has certain theoretical significance and engineering application value.