A method of encoding a digital image that is divided into a plurality of blocks of pixels. The method includes, for a current block: predicting the current block values from at least one block previously processed; calculating a residual block; obtaining a residual block by applying a transform to pixels of the residual block; selecting coefficients signs to be predicted in the transformed residual block; predicting the selected signs encoded and decoded neighbouring blocks; calculating a prediction indicator from the predictions of the selected signs and their original values; entropic encoding the indicators obtained for the predicted signs; and determining a context of a coefficient of the current residual block and the sign of a coefficient of the transformed residual block is selected based on a predetermined score associated with the encoding context of the coefficient, the score being representative of a reliability level of the prediction of the sign.