A color defined by a chroma point and by a luma value is adjusted by defining a reference chroma point and shifting the chroma point towards the reference point if the chroma point is within a predefined tilted rectangle in the chroma coordinate plane that encloses the reference point; or if the chroma point is within both of two predefined polygons, in the chroma coordinate plane, that enclose the reference point; or if the luma value is within a predefined luma range. Preferably, the two polygons are a rectangle and a rhombus. The chroma point is shifted using a continuous shift function that vanishes on the rectangle and on the rhombus.