A compensation method of spectral mismatch for a color filter array (CFA) comprising of white, red, green, and blue (WRGB) color filters includes introducing an offset representing spectral mismatch to modify a linear model that relates a W component of a pixel to R, G, and B components of the pixel. In one embodiment, an estimated offset is generated according to readout component images, and a compensated component image is generated according to the estimated offset and a corresponding readout component image.