This determination comprises: defining key constant-hue leaves such as to partition the gamut mapping color space into angular hue sectors; for each key constant hue leaf, defining a key hue leaf chroma mapping function; for each angular hue sector, defining a continuous angular hue sector chroma mapping function such that, for any source color belonging to one of the two key constant-hue leaves delimiting this angular hue sector, this continuous chroma mapping function allows to map the chroma of said source color according to the key hue leaf chroma mapping function of the key constant-hue leaf to which said source color belongs. Preferably, this mapping functions are non linear polynomials.