PURPOSE: To reduce number of field memories by providing a video memory storing a video signal for one field, a difference signal detection means, a key memory and a control means controlling the storage and write.
CONSTITUTION: When a difference signal detection means 4 detects a difference signal and a signal being an output of a key memory 6 representing that the difference signal is not a detected picture element position is outputted, a control means 19 controls the device such that the video signal at the picture element position resulting from the detection of the difference signal is stored in a video memory 12. Moreover, when the difference signal detection means 4 detects a difference signal or the key memory 6 outputs a signal representing a position resulting from the detection of the difference signal precedingly, the control means 19 controls so that the position is written in the key memory 6 as a position at which the difference signal is detected.
OGAWA KAZUYA
ASAO MOTOAKI
UEYAMA HIROYUKI
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