The consistency of the white point with the input gray level is referred in the world of display technology as gray tracking. Gray tracking is an issue for Twisted Nematic (TN) TFT-LCD screens which typically show a bluish shift of the white point when the gray level decreases. This paper discusses some causes of the colorcast in TN displays and proposes a method for correcting it by using the existing video card look-up tables (VLUT) in the graphic controller or in the panel itself. The correction process performs the gamma correction and the gray tracking correction simultaneously. The gray tracking correction uses the luminance and the chrominance information of the R, G, B channels. For a single VLUT entry, for the corresponding output value in one channel (G for example), the method computes the output values for the other two channels (R and B respectively) such that, the resulted gray has the minimum chromatic difference to the desired white point of the display. The method proves to remove the colorcast in the TN TFT-LCD screens. The method is general and can be applied to any display technology.