A decoding system generates a predicted image, receives error correcting information encoding an original image, and uses the predicted image and the error correcting information to carry out a multi-stage decoding process that reconstructs the original image by correcting prediction errors in the predicted image. This process uses correlation information representing an assumed correlation between the predicted image and the original image. As the decoding process proceeds, the correlation information is updated to reflect assumed or inferred changes in the correlation between the predicted image and the original image. Updating the correlation information permits more efficient coding by enabling the original image to be reconstructed to an acceptable level of image quality with less error correcting information.