An image encoding and decoding apparatus and method, the image encoding and decoding apparatus includes: an encoding unit adjusting at least one weight value adaptively to the number of bits expressing each pixel of a current image, predicting a pixel value of a block of interest by performing an operation on a pixel value of at least one block having a pixel value similar to the pixel value of the block of interest among blocks included in a previous image and the at least one adjusted weight value, and encoding the pixel value of the block of interest using the predicted pixel value of the block of interest; and a decoding unit adjusting the at least one weight value adaptively to the number of bits, restoring the predicted pixel value of the block of interest by performing an operation on the pixel value of the at least one block having the pixel value similar to the pixel value of the block of interest among blocks included in the restored previous image and the at least one adjusted weight value, and decoding the pixel value of the block of interest using the restored pixel value, wherein the previous image refers to an image displayed prior to a current image, and the block of interest is a target block of interest among blocks belonging to the current image.