Automated Colorization of Segmented Images Based on Color Harmony

We propose in this paper an automated colorization of segmented images based on a color harmony rule defined by Itten called the contrast of proportion. Artists create an image drawing a sketch and filling its regions following harmony rules. The most significant regions are generally filled first because of their meaning. Then the other regions are filled depending on the previous colors. Our model is able to process images composed of totally blank or partially filled regions. The user defines sectors representing colors on the chromatic hue wheel and may redefine each color proportion. Then a set of colors is selected to compute the desired harmony. To proportionally colorize an image, already existing colors can be taken into account or the harmony can be applied only to blank regions. Each region is filled with only one color and cannot be divided. Thus, exact proportion contrast colorization of segmented images is a difficult algorithmic problem. In order to solve this problem we use different strategies and propose different methods to fill the regions. If they exist, exact solutions are proposed, otherwise three different approximation methods are used to determine combinations of colors-regions close to the defined proportions. Once the image is processed, the user can adapt hue (in the chosen sector), saturation and value of each region to enhance the result. Our results show that our model is flexible and well designed to help artists, illustrators, comics creators or any other user to automatically colorize (partially or totally) their images. Keywords-harmony; colorization; stylization; enhancement; image processing;