Camera Vignetting Compensation Based On Space Adaptive Least Square Method

At present,the world has entered the era of large-scale,high-resolution new high-end digital flat panel display,which has become a leading pillar industry in the information age.With the continuous progress of LED display technology,high-density small space high-definition large screen LED display products become one of the most important display equipment,widely used in traffic management center,command center,television broadcast center,industrial monitoring and other fields.High density and small spacing LED products have the advantages of high brightness,ultra-high definition,high color saturation,wide viewing angle,seamless infinite splicing,etc.,while the high-performance display control system can further improve the image display quality by improving the depth definition and uniformity,etc.,which can meet the higher display performance requirements of the new generation of large screen high-end display products.With higher density and larger size screen display becoming a hot spot in film and television industry,the market puts forward higher requirements for high-density LED display technology.However,due to the improvement of pixel density,more LED chips are needed for the same size led screen.The same batch of semiconductor wafers cannot meet the requirements of LED chip quantity.Different batches of wafers will be used.Due to the difference of batches,the distribution of discrete characteristics of LED chips becomes difficult to control,resulting in the decrease of screen uniformity.For high-density and large-size LED chips Display products are a huge challenge.The most effective way to solve the problem of brightness uniformity is to eliminate the brightness difference of LED chips and improve the display consistency by using the brightness parameters of LED chips in the display system.The basis of this method is to get the luminance parameters of LED chip accurately,which provides the basis for correction.With the development of optoelectronic devices,the optical acquisition device(such as CCD camera)can acquire the brightness information of each pixel point by collecting the brightness of the display screen point by point,so as to achieve the purpose of collecting the brightness parameters;as the LED display screen is developing rapidly towards ultra-high density,ultra-small spacing and ultra large screen,the number of display pixels is increasing,and the size of the display screen is increasing Because of the variety of display screen shapes,the resolution of CCD optical camera can't meet the demand of point by point acquisition.Therefore,the camera needs multi angle,multi station and multiple acquisition to realize the point by point acquisition of display screen pixels,while the optical vignetting characteristics of the camera seriously affect the accuracy of screen edge acquisition,and the edge effect of multiple acquisition data can't guarantee the uniformity correction of the whole display screen,which becomes a new problem of acquisition and correction.In this paper,the optical vignetting characteristics will be accurately compensated to achieve the brightness collection of high-density large-size LED display screen,so as to improve the uniformity quality of the display screen.In the traditional method of vignetting compensation,the method of using integrating sphere to compensate the camera's vignetting needs a white field integrating device with uniform brightness,which is complex in structure and inconvenient in operation,so it is not suitable for engineering application;although the method of using image processing to compensate the camera's vignetting is simple in operation,it requires strict camera position and is not easy to operate.Aiming at the above problems,this paper proposes a space adaptive compensation method of camera vignetting,which uses the combination of the pan tilt and the camera to collect the brightness and compensate the camera vignetting.This method improves the accuracy of camera acquisition,especially meets the requirements of ultra-high density,ultra-small spacing and ultra large size led display,makes up for the defects of traditional methods,improves the acquisition and correction speed and efficiency,lays the foundation for the engineering and industrial application of homogenization technology,and improves the product quality and market competitiveness of LED display.