Fast and fully automated video colorization

Colorization is the process of adding colors to grayscale images. This is done to restore or enhance old films or photographs. Most of the techniques for the colorization of an image or video require manual designation of the locations to be colored and the colors themselves which is an expensive and time consuming process. In this paper, we propose a fast but effective fully automated technique for coloring the gray scale image sequences. We define a notion of a most informative frame which is to be coloured manually and exploit the motion field between frames for propagation of the colors to the remaining frames. The proposed technique attempts to provide a method to minimize the amount of labour required for colorization and to decrease the computational cost of this task. The most informative frame is one which has almost all the objects present in that scene. The motion field estimation is based on optical flow. A final refinement step uses similarity based colour filling. Extensive testing of the proposed technique on a large set of videos from movies and animation confirms that it is efficient and effective without any loss of quality.