Imaging system and pixel signal readout method
View Patent ↗An imaging system including a frame rate setter and an exposure evaluator. The frame rate setter sets a frame rate used in a focusing operation. The frame rate is set faster than a normal frame rate. The exposure evaluator evaluates the exposure of a focusing image based on pixel signals read out from a focusing image area at the frame rate. The frame rate is reduced when the exposure is evaluated as an underexposure and the focusing operation is carried out at a reduced frame rate.
1. An imaging system, comprising:
a frame rate setter that sets a frame rate used in a focusing operation, said frame rate being set faster than a normal frame rate;
an exposure evaluator that evaluates the exposure of a focusing image based on pixel signals read out from a focusing image area at said frame rate,
said frame rate being reduced when said exposure is evaluated as an underexposure and said focusing operation being carried out at a reduced frame rate; and
a flicker detector that detects flickering in ambient light, and when flickering is detected said frame rate is adjusted to a flicker period of the ambient light,
wherein said focusing operation is carried out by adjusting said frame rate to a multiple of said flicker period when said exposure under a frame rate adjusted to said flicker period is evaluated as an underexposure.
2. The imaging system according to claim 1 , further comprising a monitor that displays said focusing image obtained in said focusing operation.
3. The imaging system according to claim 1 , wherein said imaging system comprises a digital camera.
4. A pixel signal readout method, comprising:
setting a frame rate used in a focusing operation, said frame rate being set faster than a normal frame rate;
evaluating an exposure of a focusing image based on pixel signals read out from a focusing image area at said frame rate;
said frame rate being reduced when said exposure is evaluated as an underexposure and said pixel signals being read out at a reduced frame rate;
detecting flickering in ambient light and adjusting said frame to a flicker period of the ambient light when flickering is detected; and
carrying out said focusing operation by adjusting said frame rate to a multiple of said flicker period when said exposure under a frame rate adjusted to said flicker period is evaluated as an underexposure.