A color calibrator of a display apparatus is disclosed. The color calibrator includes a color estimator for receiving a plurality of digital counts of initial colors of an image signal. The color estimator includes a first operator, a gray value electrical-optical converter, a mixed-color electrical-optical converter, an initial color electrical-optical converter, a plurality of linear transformers and a weighting operator. The gray value electrical-optical converter, the mixed-color electrical-optical converter and the initial color electrical-optical converter convert a gray value digital count, a mixed color digital count and an initial color digital count for generating a plurality conversion outputs according to a plurality of gray conversion curves, a plurality of mixed color conversion curves and a plurality of initial color converting curve. The weighting operator receives the conversion outputs and a plurality of weighting values to generate an analysis output signal.