An output compensating device capable of effectively correcting pixel signals composing an image taken and output by the image sensor having a wide dynamic range to be adaptively displayed with high quality and high contrast on a viewable screen area by using means for detecting a minimal value and a maximal value of sensor (pixel) signals output from the image sensor to be displayed on the screen area, means for offsetting the detected minimal value of the sensor signal to a lower limit value of the screen area and means for adjusting a gain of the sensor signal in such a way that an output width determined by the detected minimal and maximal values of the sensor signals may be equal to the maximal width or a specified width of the screen area.