Dichromatic Illumination Estimation via Hough Transforms in 3D
Shi, L. and Funt, B.,
"Dichromatic Illumination Estimation via Hough Transforms in 3D,"
Proc. CGIV2008 IS&T Fourth European Conf. on Colour in Graphics, Imaging and Vision Barcelona,
June 2008.
Abstract:
A new illumination-estimation method is proposed based
on the dichromatic reflection model combined with Hough
transform processing. Other researchers have shown that
using the dichromatic reflection model under the assumption of
neutral interface reflection, the color of the illuminating light
can be estimated by intersecting the dichromatic planes created
by two or more differently coloured regions. Our proposed
method employs two Hough transforms in sequence in RGB
space. The first Hough Transform creates a dichromatic plane
histogram representing the number of pixels belonging to
dichromatic planes created by differently coloured scene
regions. The second Hough Transform creates an illumination
axis histogram representing the total number of pixels
satisfying the dichromatic model for each posited illumination
axis. This method overcomes limitations of previous
approaches that include requirements such as: that the number
of distinct surfaces be known in advance, that the image be pre-
segmented into regions of uniform colour, and that the image
contain distinct specularities. Many of these methods rely on
the assumption that there are sufficiently large, connected
regions of a single, highly specular material in the scene.
Comparing the performance of the proposed approach with
previous non-training methods on a set of real images, the
proposed method yields better results while requiring no prior
knowledge of the image content.
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