An image pickup system includes a color noise estimation section, which has a local region extraction section that extracts luminance and color difference signals in units of 4.times.4 pixels from signals of a CCD with a color filter, an average luminance calculation section that calculates an average luminance value from the luminance signals, a temperature estimation section that estimates a temperature T of the CCD from a signal of an OB region, a gain calculation section that calculates a gain G of the signals based on information from a control section, a coefficient and a function calculation sections for estimating a color noise amount from the average luminance value based on a formulation using the temperature and the gain, and a color noise reducing section that reduces color noise in the color difference signals in units of 4.times.4 pixels based on the estimated color noise amount.