1. A method for detecting a preferred color, the method comprising: comparing a hue value of an input pixel with hue reference values and detecting a first preferred-color pixel; and performing a best linear estimation (BLE) operation with respect to the first preferred-color pixel and detecting a second preferred-color pixel, wherein the detecting of the second preferred-color pixel includes: calculating a preferred-color discrimination constant by a matrix product of an input matrix composed of characteristic data of the first preferred-color pixel and a weight vector matrix composed of weight vectors of the preferred color; and comparing the calculated preferred-color discrimination constant with a reference value of the preferred-color discrimination constant, detecting the pixel as the second preferred-color pixel if the preferred-color discrimination constant is included in a range of the reference value of the preferred-color discrimination constant, and detecting the pixel as the non-preferred-color pixel if the preferred-color discrimination constant is not included in the range of the reference value of the preferred-color discrimination constant.