Image processing apparatus with change over of clock signals

摘要

In order to enable sampling of high definition still video signals in addition to common video signals, a function is added for sampling video signals with every other plurality of picture elements as an interval to an image processing apparatus without using a sampling circuit which requires high speed operations. The invention is also intended to change over between two circuits that is, a circuit for using a picture element clock regenerated by a PLL circuit as a sampling clock for analog to digital converters and a circuit for using a clock obtained by dividing the picture element clock as a sampling clock for the analog to digital converters to sample video signals with every other plurality of picture elements as an interval. Thus, it is possible to carry out sampling of high definition video signals with high frequencies in addition to common video signals without necessity of raising the operating speed of the sampling circuit.