1. An image sensing system, comprising: a lens shading correction module to correct a gain of each pixel of a captured image for optical shading effects, the lens shading correction module storing a two-dimensional correction surface in which an image sensor is partitioned into at least three sections in an x-dimension and at least three sections in a y-dimension to form at least nine different rectangular-shaped zones with each zone having a first piecewise continuous quadratic polynomial correction curve in an x-dimension and a second piecewise continuous quadratic polynomial correction curve in a y-dimension, the number of zones being selected to achieve accurate shading correction of both a center portion of the image and edge portions of the image; wherein there is a correlation in shading response between different color channels, the two-dimensional correction surface corresponding to a single color channel (C 1 ) having a first number of associated control points and wherein each additional color channel (C n ) has a correction surface represented as a correction surface normalized by the response of the single color channel (C n /C 1 ) and having a second number of associated control points less than said first number.