1. A method for adjusting image color values, said method comprising: a) dividing a first color gamut into a plurality of color regions, represented by polygons having vertices, wherein one or more of said color region polygons are at least partially bounded by a line defined by the constraint whereby a red value of a color equals a blue value of said color divided by a constant and a line defined by the constraint whereby a red value of a color equals a green value of said color divided by another constant, wherein neither constant equals one; b) defining control points at the vertices of said color regions; c) selecting a target color, wherein said target color is defined by first target coordinates related to said first color gamut; d) determining a first color region, in said plurality of color regions, where said target color is located; e) determining first color region control point coordinates for said control points corresponding to said first color region; f) determining a target color weighting vector using said first target coordinates and said first color region control point coordinates; g) converting said first color region control point coordinates to relate to a second color gamut thereby creating second-gamut control point coordinates; and h) calculating second-gamut target color coordinates related to said second color gamut by combining said target color weighting vector with said second-gamut control point coordinates.