Methods and systems herein provide for color conversion of image data to another color space. Such color conversion includes converting image data to a color space by identifying color regions in the image data. One color conversion system herein includes a color region identifier operable to select color values in the image data, determine numerical centers of the selected color values, and generate color regions, or color value “clusters”, based on the selected color values and the numerical centers. The color conversion system also includes an optimization module operable to refine the numerical center of each color region, determine a boundary for each color region based on the refined center, and remove a portion of the color cluster centers to optimize a number of the color regions for color conversion processing.