1. A method of reducing image noise, comprising: selecting one from unreconstructed pixels of an image containing a plurality of pixels as a target pixel, and setting a plurality of reference pixels corresponding to the target pixel; calculating a range value of each reference pixel to the target pixel, meanwhile obtaining an intensity deviant by converting an intensity of the target pixel, and then calculating a range weight value of each reference pixel to the target pixel by the intensity deviant and the range value; calculating a domain weight value of each reference pixel to the target pixel according to a domain value of each reference pixel corresponding to the target pixel; calculating a smoothness value of the target pixel, obtaining a smooth weight value by converting the smoothness value, and adjusting the domain weight value with the smooth weight value by adjusting the strength of a domain weight filter; and reconstructing the target pixel according to the range weight value of each reference pixel to the target pixel and the adjusted domain weight value.