A method for color conversion includes calculating distances between color coordinates in a conversion palette and a color coordinate for a pixel and assigning the pixel a color coordinate of the closest color coordinates in the conversion palette. The color coordinates in the conversion palette include a first point and a second point in an RGB color cube on a neutral axis of said RGB color cube and on opposite surfaces of a first sphere, a third point and a fourth point on the neutral axis and on opposite surfaces of a second sphere and on the neutral axis, and a plurality of other points distributed over a surface of the first sphere and around the neutral axis, where a volume of the second sphere is twice the volume of the first sphere, and a center of the first and second spheres is a center of the RGB color cube.