An image encoding/decoding system, medium, and method. The image encoding system includes a residue production unit arranged to produce first residues corresponding to differences between color components of a current image and color components of a predicted image, a unit arranged to perform spatial transform and quantization with respect to the first residue of a first color component and perform de-quantization and inverse spatial transform with respect to the quantized first residue of the first color component so as to reconstruct the first residue of the first color component, a residue prediction unit arranged to predict second residues with respect to the first residues of the other color components by using the reconstructed first residue of the first color component, and an encoding unit arranged to encode the first residue of the first color component and the second residues of the other color components.