Method for decoding a data signal representative of at least one image divided into partitions that has been encoded beforehand, a current partition (Bi) to be decoded comprising coefficients of a direct transformation of the current partition (Bi) and the signs of the coefficients with the exception of the sign of the first non-zero coefficient of said current partition (Bi) which may be hidden, said decoding method comprising, for said current partition (Bi), steps of: - decoding (SD2, SD3) data of said current partition (Bi), but not said sign; - determining the value of said sign, the determination of the value of said sign comprising the steps of: if said number of coefficients between the first and last non-zero coefficients including the first and last non-zero coefficients is lower than a predefined threshold (TSIG), determining that said sign is not hidden but that it is contained in the data of said current partition (Bi), or if said number of coefficients between the first and last non-zero coefficients including the first and last non-zero coefficients is higher than or equal to the predefined threshold (TSIG), determining that said sign is hidden and that the parity of the sum of said coefficients between the first and last non-zero coefficients indicates the value of said hidden sign, and if the sum of said coefficients between the first and last non-zero coefficients is even, determining that said hidden sign is positive, or if the sum of said coefficients between the first and last non-zero coefficients is uneven, determining that said hidden sign is negative. - decoding (SD2, SD3) data of said current partition (Bi), but not said sign; - determining the value of said sign, the determination of the value of said sign comprising the steps of: if said number of coefficients between the first and last non-zero coefficients including the first and last non-zero coefficients is lower than a predefined threshold (TSIG), determining that said sign is not hidden but that it is contained in the data of said current partition (Bi), or if said number of coefficients between the first and last non-zero coefficients including the first and last non-zero coefficients is higher than or equal to the predefined threshold (TSIG), determining that said sign is hidden and that the parity of the sum of said coefficients between the first and last non-zero coefficients indicates the value of said hidden sign, and if the sum of said coefficients between the first and last non-zero coefficients is even, determining that said hidden sign is positive, or if the sum of said coefficients between the first and last non-zero coefficients is uneven, determining that said hidden sign is negative. if said number of coefficients between the first and last non-zero coefficients including the first and last non-zero coefficients is lower than a predefined threshold (TSIG), determining that said sign is not hidden but that it is contained in the data of said current partition (Bi), or if said number of coefficients between the first and last non-zero coefficients including the first and last non-zero coefficients is higher than or equal to the predefined threshold (TSIG), determining that said sign is hidden and that the parity of the sum of said coefficients between the first and last non-zero coefficients indicates the value of said hidden sign, and if the sum of said coefficients between the first and last non-zero coefficients is even, determining that said hidden sign is positive, or if the sum of said coefficients between the first and last non-zero coefficients is uneven, determining that said hidden sign is negative. if the sum of said coefficients between the first and last non-zero coefficients is even, determining that said hidden sign is positive, or if the sum of said coefficients between the first and last non-zero coefficients is uneven, determining that said hidden sign is negative.