To generate a video signal whose dynamic range is extended without addition of a circuit to the signal processing of an existing camera by selecting a characteristic of a gamma processing circuit used for the existing camera depending on a long time exposure signal or a short time exposure signal at any time so as to conduct the processing suitable for each exposure.
A signal amount outputted from a CCD image pickup element 102 is sequentially switched to long time exposure and short time exposure by selecting an amount of an electronic shutter given to the CCD image pickup element 102 in the unit of one field. A video signal sequentially switched by the electronic shutter is given to a gamma correction circuit 107, where the video signal receives nonlinear transformation processing. In this case, a changeover switch 110 selects the conversion characteristic of the processing conducted by the gamma correction circuit 107. A memory circuit 108 stores the long time exposure and the short time exposure corrected by the gamma correction circuit 107. Then an offset is added to the short time exposure signal whose signal quantity is less and the sum is added to an output of the gamma correction circuit 107. The resulting video signal after the summing is an analog TV signal.
NISHIZAWA AKIHITO
NISHIMURA RYUSHI
HITACHI VIDEO & INF SYST