: Given a grayscale image marked with some color scribbles by the user (left), our algorithm produces a colorized image (middle). For reference, the original color image is shown on the right. Colorization is a computer-assisted process of adding color to a monochrome image or movie. The process typically involves segmenting images into regions and tracking these regions across image sequences. Neither of these tasks can be performed reliably in practice; consequently, colorization requires considerable user intervention and remains a tedious, time-consuming, and expensive task. In this paper we present a simple colorization method that requires neither precise image segmentation, nor accurate region tracking. Our method is based on a simple premise: neighboring pixels in space-time that have similar intensities should have similar colors. We formalize this premise using a quadratic cost function and obtain an optimization problem that can be solved efficiently using standard techniques. In our approach an artist only needs to annotate the image with a few color scribbles, and the indicated colors are automatically propagated in both space and time to produce a fully colorized image or sequence. We demonstrate that high quality colorizations of stills and movie clips may be obtained from a relatively modest amount of user input.
Levin et al. REF formulated an optimization problem based on an assumption that neighboring pixels of similar intensity should have similar color values under the limitation that the colors indicated in the scribbles remain the same.
Colorization using optimization
SIGGRAPH '04
Computer Science