| 摘要 |
PURPOSE:To obtain a normal color picture by separating a luminance component signal read from a memory and D-A converted, inverting the polarity of a difference signal to this luminance component signal, alternatively taking-out the difference signal and a polarity inverting signal for each prescribed frequency and extracting a color modulation wave. CONSTITUTION:A signal of one line is stored as a digital signal and the digital signal, which is read in a reverse time sequence, is defined as the pulse train (sampling signal) of a 4fsc clock frequency by a D/A converter 12. The 4fsc pulse train of the color modulation wave is formed by separating a luminance component from this signal by a low-pass filter 13 and making difference to the output of the D/A converter 12. Next, the polarity inversion is alternatively executed to the pulse of this pulse train and afterwards, the pulse is passed through a band pass filter 16, whose central frequency is fs, and defined as the color modulation wave. Thus, the picture of correct hue can be obtained by the demodulating circuit of a normal NTSC signal 1. |
