METHOD AND APPARATUS FOR DETERMINING AN OUTPUT VALUE REPRESENTING A PICTURE DATA BY APPLYING A PIECE-WISE LINEAR FUNCTION ON AN INPUT DATA REPRESENTING A PICTURE DATA

摘要

A method and apparatus for determining an output value representing a picture data by applying a piece-wise linear function on an input value representing a picture data, said piece-wise linear function comprising at least one piece characterized by a slope value ai, an offset value and an interval defined over a range of values comprised between a lower bound and an upper bound. The method comprises: —obtaining (50) a coded input value X coded with quantization on n bits; —obtaining (51) a coded slope value Ai, said coded slope value Ai representing a mantissa value ai_m coded with m bits and an exponent of 2 value ai_e coded with (K−m) bits, K being the total number of bits to code said slope value ai; —identifying the (K−m) most significant bits of the coded slope, said (K−m) most significant bits forming an exponent value ai_e of a decoded slope value; —identifying the m least significant bits of the coded slope value, said m least significant bits forming the mantissa ai_m of the decoded slope value; —determining (52) the output value y by shifting the product of the mantissa ai_m of the decoded slope and the coded input data X by an integer value equal to (n+m−ai_e−p).