1. A lens shading correction (LSC) system, comprising: an LSC circuit configured to receive input pixel data of a current frame; an illuminant estimator configured to calculate at least one spectral association-measurement of the current frame according to the input pixel data or output pixel data of the LSC circuit, and then to correlate the at least one calculated spectral association-measurement with spectral association-measurements of a plurality of pre-defined illuminants to determine at least one correlated illuminant; an LSC parameter generator coupled to receive the at least one correlated illuminant; and a pre-calibrated LSC parameter memory, from which the LSC parameter generator retrieves at least one set of pre-calibrated LSC parameters; wherein the LSC parameter generator generates a set of LSC parameters based on the at least one retrieved set of pre-calibrated LSC parameters according to the at least one correlated illuminant, the generated set of LSC parameters being then forwarded to the LSC circuit to correct pixel data of a succeeding frame; wherein the illuminant estimator comprises: a spectral association-measurement calculator coupled to receive the input or output pixel data in order to calculate the at least one spectral association-measurement; and an edge detector disposed in front of the spectral association-measurement calculator and configured to extract on-edge pixel data from the input or output pixel data, the on-edge pixel data being then forwarded to the spectral association-measurement calculator.