Methods and systems herein provide for color conversion of image data to another color space, such as that of a printer. Such color conversion includes linearly processing the color conversions when using radial basis functions for the conversions. One color conversion system herein includes a modeling module operable to generate a numerical model according to a radial basis function for converting the color values in the image data to the color space. The numerical model includes error approximations operable to form the radial basis function into a linear process. The system also includes a color converter operable to convert the color values in the image data to the color space based on the numerical model.