System and method for convert rgb to rgbw color using white value extraction

An RGB-TO-RGBW transform system and a method thereof for extracting white value which appropriately reflects the luminance value and chroma value are provided to convert the RGB of input pixel by using a tetrahedral interpolation through an RGBW lockup table. A color space conversion part(102) converts the RGB value of the input pixel into the color space in which luminance and chroma are independent. By using the luminance value and saturation value of the input pixel, a maximum saturation value decision part(103) determines the maximum saturation value positioned in the color gamut boundary of the color space. The point positioned at the color gamut boundary of the color space is determined as the maximum saturation value. A white value calculation part(104) calculates white value of the input pixel by using chroma ratio and luminance value determined according to the maximum saturation value.