1. Image color correction method for a camera, comprising the steps of: (a) providing a plurality of reference color values; (b) providing color images captured by a camera of said plurality of reference colors; (c) computing gray-preserving coefficients for an optimized color correction transformation of color values of said captured images into corresponding ones of said reference color values, wherein said transformation is of the form: [ R ′ G ′ B ′ ] = [ M 11 M 12 M 13 M 21 M 22 M 23 M 31 M 32 M 33 ] - [ R G B ] + [ O 1 O 2 O 3 ] , ⁢ and wherein R′, G′, B′ are ideal R, G, B values and wherein M and O relate to optimal transformation matrix and the offset vector, respectively and wherein said gray-preserving is the constraint Σ 1≦j≦3 M 1,j =Σ 1≦j≦3 M 2,j =Σ 1≦j≦3 M 3,j ; and (d) setting a color correction function of said camera with said coefficients.