Colorization using Optimization
School of Computer Science and Engineering
The Hebrew University of Jerusalem∗
Figure 1: 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 seg-
menting images into regions and tracking these regions across im-
age sequences. Neither of these tasks can be performed reliably in
practice; consequently, colorization requires considerable user in-
tervention and remains a tedious, time-consuming, and expensive
In this paper we present a simple colorization method that re-
quires 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 pro-
duce 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.
I.4.9 [Image Processing and Computer Vision]:
Keywords: colorization, recoloring, segmentation
Colorization is a term introduced by Wilson Markle in 1970 to de-
scribe the computer-assisted process he invented for adding color
to black and white movies or TV programs [Burns]. The term is
now used generically to describe any technique for adding color to
monochrome stills and footage.
Colorization of classic motion pictures has g