Abstract:
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In cinema and TV it is quite usual to have to work with footage coming from several
cameras, which show noticeable color differences among them even if they are all the same model.
In TV broadcasts, technicians work in camera control units so as to ensure color consistency when
cutting from one camera to another. In cinema post-production, colorists need to manually colormatch
images coming from different sources. Aiming to help perform this task automatically, the
Academy Color Encoding System (ACES) introduced a color management framework to work within
the same color space and be able to use different cameras and displays; however, the ACES
pipeline requires to have the cameras characterized previously, and therefore does not allow to work
‘in the wild’, a situation which is very common. We present a color stabilization method that, given
two images of the same scene taken by two cameras with unknown settings and unknown internal
parameter values, and encoded with unknown non-linear curves (logarithmic or gamma), is able to correct the colors of one of the images making it look as if it was captured with the other camera. Our
method is based on treating the in-camera color processing pipeline as a combination of a 3x3 matrix
followed by a non-linearity, which allows us to model a color stabilization transformation among two
shots as a linear-nonlinear function with several parameters. We find corresponding points between
the two images, compute the error (color difference) over them, and determine the transformation
parameters that minimize this error, all automatically without any user input. The method is fast and
the results have no spurious colors or spatio-temporal artifacts of any kind. It outperforms the state of
the art both visually and according to several metrics, and can handle very challenging real-life
examples. |
Abstract:
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This work was supported by the European Research Council, Starting Grant ref. 306337, by the
Spanish government and FEDER Fund, grant ref. TIN2015-71537-P(MINECO/FEDER,UE), and
by the Icrea Academia Award. The work of J. Vazquez-Corral was supported by the Spanish
government under Grant IJCI-2014-19516. |