A prediction value determination method, an encoder and a decoder are provided. The method is applicable to an encoder or a decoder, and the method comprises: acquiring reconstructed blocks of a block to be encoded, a number of the reconstructed blocks being more than one; processing template pixel matrices of the reconstructed blocks according to preset processing parameters to obtain processed template pixel matrices; determining a matched block of the block to be encoded according to the processed template pixel matrices; and determining a pixel matrix of the matched block of the block to be encoded as a prediction of the block to be encoded.