The invention provides a novel color image coding method. The method is characterized by, according to the characteristic that a transfer matrix between RGB and YCbCr color space is a non-unitary matrix, that is, unequivalence of error between RGB images and YCbCr images, with minimization of interpolation error of an RGB space being an objective, carrying out combined optimized filtering on three components of Y, Cb and Cr, after filtering, the resolution of the component Y keeping unchanged, and the resolutions of the two components Cb and Cr being reduced; after finishing filtering, carrying out compression on the three components through a standard JPEG image compression method; and carrying out coding on the RGB images based on the above, so that coding efficiency is improved greatly. The method can improve coding efficiency of the RGB color images, is not high in complexity and is easy to realize.