Display and method of displaying an image with a pixel

A display, comprising:

• a plurality of pixels, each of the plurality of pixels comprising a first sub-pixel, a second sub-pixel, a third sub-pixel and a fourth sub-pixel, the pixel being used for receiving a plurality of signal values to display images, wherein the signal values are N-bit signal values, and a largest value of the signal values is (2N−1);
• a signal providing device for providing a first signal, a second signal and a third signal;
• a color saturation value generating device for generating a color saturation value corresponding to the first signal, the second signal and the third signal;
• a signal transforming device, for transforming the first signal, the second signal and the third signal into the first output signal, the second output signal, the third output signal and the fourth output signal when the color saturation value is substantially not larger than a predetermined value;
• and
• a display panel for using the first output signal, the second output signal, the third output signal and the fourth output signal to display images corresponding to the first sub-pixel, the second sub-pixel, the third sub-pixel and the fourth sub-pixel respectively so as to form images of the pixel;
• wherein the fourth output signal is not smaller than the first output signal, the second output signal and the third output signal, and N is a positive integer.