In a scanning line number converting device, a videosignal is converted into a digital signal, its scanninglines being thinned out by a thinning-out circuit (5) inthe vertical direction to reduce the vertical directionsampling frequency and interpolated so as to form anon-interlace signal. The non-interlace signal is writtenin a frame memory (7), under control of a writing controlcircuit (8). A field determination circuit (15)determines a field of a video signal used as reference.According to this determination output, the non-interlacesignal is read out of the frame memory while undergoing aconversion into an interlace signal such that itsinterlace sequence corresponds to that of the referencevideo signal, resulting in a conversion of the scanningline number. A down-converter for converting ahigh-resolution TV signal into an NTS signal is configuredusing this scanning line number converting device. Also,a picture-in-picture television is configures using thescanning line number converting device so as to thin outthe scanning lines of a video signal of a sub-pictureinserted into a main picture.
展开▼
