1. A method of reducing an amount of black in an image, utilizing a computer to reduce or eliminate an amount of black in an original digital image, so as to obtain a converted digital image, the method comprising the following steps: reading the original digital image, which comprises P original pixels, wherein 1≦P≦9,000,000,000, and each original pixel comprises three types of color information including the following: R color information referring to a red value; G color information referring to a green value; and B color information referring to a blue value, where: 
 0≦ R≦F, 0≦ G≦F, 0≦ B≦F , wherein 2 4 −1≦ F≦ 2 32 −1; preparing a digital image under conversion, which comprises N×N×P pixels under conversion, wherein N is 2 or 3, and each original pixel corresponds to N×N pixels under conversion; and generating color information of the N×N pixels under conversion corresponding to each original pixel, wherein at least N×N pixels under conversion corresponding to one original pixel have passed through a black reduction process, and the color information of the corresponding N×N pixels under conversion meets at least one of the following conditions: 
 0.8× F≦R≦F, 0.8× F≦G≦F , or 0.8× F≦B≦F; thereby obtaining a converted digital image after completing the color information of the digital image under conversion.