Amplifying image signal with changing gains

A driving method of an imaging system comprising a solid-state imaging device having a plurality of pixels, arranged in an array, each for outputting an image signal based on a noise component and an image signal based on the noise component and a photoelectric conversion, in that order, column amplifiers each corresponding to each of columns of the pixels and an output portion for outputting the image signals based on an amplification by the column amplifier;

• and
• a signal processing unit receiving the image signals, wherein
• the method comprising steps of:
• amplifying, by the column amplifier, the image signals outputted from the pixel, wherein a gain of the column amplifier is changed from a first gain to a second gain while the image signal based on the noise component is applied to the column amplifier, the image signal based on the noise component and the photoelectric conversion is applied to the column amplifier while the column amplifier maintains the second gain, the gain of the column amplifier is changed from the second gain to the first gain while the image signal based on the noise component and the photoelectric conversion is applied to the column amplifier, and the first or second gain is q which is greater than 1, and
• amplifying, by the signal processing unit, by a factor smaller than 1, the image signal based on the signal amplified by the column amplifier.