A color conversion apparatus is described whereby color within at least one specific region of a color picture can be converted to a different color in a reproduced picture, while enabling gradations of color and lightness within that region to be left substantially unchanged. The conversion is based upon setting of pre-calculated output values in a table memory within a color conversion section, by an initialization operation, and conversion can be a change in one color attribute or in a combination of attributes of respective color values within the selected region. The table memory subsequently responds to successive input color values supplied thereto by producing color-converted output values which can be supplied for example to a color printer apparatus, with resultant degrees of color change being determined in accordance with degrees of closeness of one attribute or a combination of attributes of each input color value to the corresponding attribute or combination of attributes of a predetermined color value.