METHOD AND SYSTEM FOR VIGNETTING ELIMINATION IN DIGITAL IMAGE

摘要

An imaging system having one or more look-up tables to compensate for vignetting effect on an image sensor by a lens. An image of a test target formed by the lens is captured by the image sensor and sampling is carried out at discrete locations distributed on a sparse grid throughout the image area. The look-up table is generated according to gain values at sampling grid locations. Two or more look-up tables may be generated for different color temperatures and different lens positions. Image area is effectively divided into a plurality of image zones, each zone defined by four grid locations. The correction gain for each pixel within a zone is calculated in run time by interpolating a gain value on the basis of the correction gain values at those four grid locations, taken into account the distance of the pixel from each of those grid locations.