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Color
Image Segmentation using
Adaptive Color Spaces
The research on Color Image Segmentation that has been performed
in the particular field of Region-Growing Segmentation algorithms has
been centered on different aspects of image segmentation strategies:
representation of global criteria for region merging (e.g. the Gradient
Network Method - http://www.lapix.ufsc.br/gnm/),
cue identification or
integration of texture information into the segmentation process. In
order to overcome limitations imposed by the traditional linear
colorspaces such as RGB, which do not represent adequately the
perceptual differences of image ares in a given context, differente
approaches have benn followed: different evaluation methods for
chromacity and luminosity have been used ([Dony and Wesolkowski, 1999]
and [Schneider et al., 2000]) and also approaches where the
segmentation switche sto differente colorspaces to differentiate
regions of clear and rough color perception in the scene of the image,
as originally discussed by [Huang et al., 2006].
We played with the idea that, instead of defining complex, multi-step
model-based schemes for color evaluation in images, why not define a
particular colorspace that reflects the color distribution encontred in
the images of a specific application area and use it for the measure of
color distances in traditional region-growing segmentation algorithms ?
This site was created to present results achieved with traditional,
well-accepted Region-Growing segmentation algorithms, when an Adapted Color Space is used instead of a simple linear colorspace.
This adapted colorspace should be a colorspace defined by the color
distribution encontered in the image itself. The first empirical
evaluations that we have performed were achieved using the Mumford and
Shah segmentation algorithm [Mumford and Shah, 1989], which is
well-known and has an extremely simple structure, in combination with
the Mahalanobis Distance, which defines a statistically inspired
data-driven non-isotropic distance measure [Mahalanobis P.C. 1936].
We also show a generalization test where images of the same context are used. This experiment can be viewed here

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Fig. a: A
linear colorspace
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Fig.b: A non-isotropic Colorspace |
For the validation of the results obtained so far, we have selected two
segmentation quality measures developed especially for image
segmentation evaluation. These measures, the Rand Index
[Rand71]
and the Bipartite Graph Matching Method [Cheng
et. al.01],
provide results in float values which are in the [0,1]
interval. These methods are based on two different quality assessment
assumptions that we consider to be representative for the state of the
art in research on automated image segmentation validation.
Both Rand and BGM are ground-truth based evaluation measures. So, every
image set selected has to have a reliable group of ground-truth images
available
for the evaluation of the experiments. For this reason, we selected our
test sets from the Berkeley
Segmentation Dataset and Benchmark [Martin
et.al.01], a
well-known natural images dataset that has at least 5 and up to 7
ground-truths for every image in its dataset. The results of evaluation measures can be downloaded here.
REFERENCES
[Cheng et. al.01] H.D. Cheng, X.H. Jiang, Y. Sun and J. Wang. Color
image segmentation: advances and prospects. Pattern Recognition 34,
2001, pp. 2259-2281.
[Dony&Wesolkowski99] Dony, R.D., Wesolkowski, S.B. 1999. Edge
detection on color images using RGB vector angles. In: Proc. 1999 IEEE
Canadian Conf. Electrical and Computer Engineering. Edmonton, Alberta,
Canada May 9–12, pp. 687–692.
[Martin et.al.01] Martin, D., Fowlkes, C., Tal, D., Malik, J. A
database of human segmented natural images and its application to
evaluating segmentation algorithms and measuring ecological statistics.
In: Proc. 8th Int'l Conf. Computer Vision. vol. 2; 2001. p. 416-423.
[Mahalanobis P.C. 1936], On the generalized distance in statistics,
Proceedings of the National Institute of Science of India 12, 49-55.
1936.
[Mumford and Shah, 1989] D. Mumford and J. Shah, Optimal approximations
by piecewise smooth functions and associated variational problems,
Commun. Pure Appl. Math. 42, pp. 577–684. 1989.
[Rand71] W. M. Rand. Objective criteria for the evaluation of
clustering methods. Journal of the American Statistical Association.
Vol. 66. pp 846/850, 1971.
[Schneider et al., 2000] M.K. Schneider, P.W. Fieguth, W.C. Karl and
A.S. Willsky, Multiscale methods for the segmentation and
reconstruction of signals and images, IEEE Trans. Image Process. 9 (3)
2000, pp. 456–468 March. Full Text via CrossRef | View Record
in
Scopus | Cited By in Scopus (18)
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