Method for enhancing image quality by saturation

The present invention relates to a method for enhancing an image quality by saturation. The method includes the step of: determining a minimum gain value 'SatGainMin' and a maximum gain value 'SatGainMax' of a gain value 'PGain' of a pre-amplifier; defining a first to a third ranges based on the 'SatGainMin' and the 'SatGainMax'; determining whether a currently used saturation value 'USat' is equal to or greater than approximately 1; determining whether the 'PGain' is less than the 'SatGainMin'; performing saturation by using a value in the first range as an actual saturation value 'ASat' when 'PGain'< 'SatGainMin'; determining whether the 'PGain' is equal to or less than the 'SatGainMax'; performing saturation by using a value in the second range as the 'ASat' when 'SatGainMin'≦'PGain'≦'SatGainMax'; and performing saturation by using a value in the third range as the 'ASat' when 'PGain'>'SatGainMax'.