A display controller, comprising a 3D_LUT random access memory, which stores at least a 3D Lookup table; and a display control processing unit, comprising: a computing unit, a register, a color signal booster, and a color signal attenuator; wherein after input color signals are received by the color signal booster, and the color signal booster amplifies color signals by a first predetermined factor, wherein the computing unit calculates the address of the 3D Lookup table, and loads the 3D Lookup table from the 3D_LUT random access memory according to the register, wherein the color signal attenuator attenuates color signals by a second predetermined factor. The present disclosure significantly increases the precision of color conversion from one RGB color space to another RGB color space, and does not increase the RAM cost, since the cost of multiplying or dividing by power of 2, for example, is limited.