JP2855698B

PURPOSE:To reduce the circuit scale of a signal source by allowing an image signal to pass through an optimized transmission matching filter, and thereafter, writing it in a memory, reading out its information by using only this memory, and using it as a signal source of an input to a decoder. CONSTITUTION:A filter coefficient of a transmission matching filter 11 of a standard video signal source 1 of a generating device is optimized by an error to an ideal signal of a transmission line measuring signal in an image signal fetched by a standard decoder 2. Subsequently, image signal information after allowing it pass through the transmission matching filter 11 which optimizes the filter characteristic is written in a memory 43 of a video signal source device, and the video signal source device reads out the information of the memory 43 and outputs a video signal for a decoder test to which an optimum filter characteristic is applied. In such a way, by using the memory 43, the video signal source device 1 can be constituted without using a circuit containing the transmission matching filter 11, and a video signal to which a filter characteristic of high accuracy is applied can be realized by a small circuit scale.