A method and system are disclosed for displaying Y-bit coded RGB image data that is received as X-bit coded RGB or YCbCr image data, where XY. The method includes receiving X-bit coded image data, where each color channel comprises m-bits; arithmetically processing the image data to include dithering noise values that result in maintaining the luminance of the image data substantially constant; converting the YCbCr image data to RGB image data, and quantizing the image data to Y-bit coded RGB image data where each color channel comprises n-bits. For example, X=24 and Y=12. The step of arithmetically processing includes, for the RGB case and for each pixel, generating an integer random number lying in the range of [-Q/2 . . . Q/2], where Q is a quantization step size; adding the random number to each of the Red and Blue color channels, and subtracting the random number from the Green color channel; and truncating and clipping the result in each color channel. Preferably, Q=2^(m-n). Preferably, the step of truncating truncates the value in each color channel to n-bits, and clipping clips the truncated values to lie in the range of [0 . . . 2ⁿ-1]. For the YCbCr case the processing step adds the random number to each of the Cb and Cr color channels, and converts the YCbCr color channels to RGB color channels. In a most preferred embodiment the step of receiving receives the X-bit coded RGB image data from a RF cellular telecommunications channel, and the steps of quantizing and arithmetically processing are performed within a cellular telephone.