There is disclosed a flat display unit which can obtain color signals adapted to a pixel arrangement. The unit has a gate drive circuit and a source drive circuit. Among R, G, B input video signals, a G signal is regarded as a color signal of a reference, R and B signals are regarded as second and third color signals, a plurality of samples of the R signal are multiplied by coefficients and synthesized to generate a first interpolation color signal R′, a plurality of samples of the B signal are multiplied by coefficients and synthesized to generate a second interpolation color signal B′. The R′, B′ and G signal are successively selected and supplied to the source drive circuit.