PURPOSE: To eliminate deviation in hue and uneven color density by calculating an interpolation data of an interpolation point from a data of two consecutive sampling points and interpolating the data based on a trigonometric function.
CONSTITUTION: Sampling data A-D of a color sampling point 8 are obtained by sampling a chrominance carrier frequency Fsc with a frequency subject to 4-multiple from a chroma input signal 7. An arithmetic circuit 5 calculates interpolation data a-d among data from the digital data A-D and an interpolation circuit 6 interpolates the interpolation data a-d calculated at each interpolation point 10 and the data quantity is doubled and a D/A converter 3 is used to convert the signal into an analog chroma signal 9 and a low pass filter (LPF) 4 implements carrier recovery to obtain a chroma output signal 11. Since the waveform of the chroma signal is always represented by a sinusoidal wave, the interpolating point is obtained by a trigonometric function and the interpolation data is obtained based on the relation of phase between the sampling point 8 and the interpolation point 10.
KUMANO MAKOTO
MORIKAWA YASUHIRO
