An LCD device includes a four-color converter for converting an original RGB data into three grayscale values, executing a white balance process to the three grayscale values, and confirming a maximum value MAX (Ri, Gi, Bi) and a minimum value of the three white-balanced grayscale values Ri, Gi, and Bi, wherein, when the minimum value is greater than 0, determining that if the three data of the original RGB data are equal, and when they are equal, utilizing a formula Wo=Bi; Ro=Ri×Wo/MAX(Ri, Gi, Bi)+Ri−Wo; Go=Gi×Wo/MAX(Ri, Gi, Bi)+Gi−Wo; Bo=0 to calculate the output grayscale values Ro, Go, Bo, and Wo in the RGBW data. The device also includes a data driver for processing the RGBW data provided by the four-color converter to generate analog type data signals, a scanning driver for sequentially generating scanning signals, and an LCD panel for displaying colors.