Clear display of high-resolution pictures on LED displays is one of key problems to be solved in displaying quality improvement areas. Aiming at the features of LED displays, such as low-resolutions, high production costs and flexible in pixels arrangements,applications of sub-pixel sampling technique were analyzed. Firstly, the mathematical models of LED displays were set up from the information processing perspective. Then under theluminance and chrominance separated space such as YUV color space, by frequency analysis,it was demonstrated that aliasing in display images can be transferred from the luminance to the chrominance which was insensitive to human eyes.The Nyquist limits of them in all directions were effectively expanded. The simulation results on the real LEDdisplay further show the improvement of displaying quality by sub-pixel sampling.