On 2 March 2010 04:56, Sven Neumann <s...@gimp.org> wrote:

> The current code is prepared for multiple algorithms as backend for the
> segmentation tool. It's not foreseen that you switch between algorithms,
> but that you pick one, but even that could probably be changed. As there
> is currently only the SIOX backend, there's no choice of algorithm
> exposed in the user interface. But it wouldn't be too difficult to add a
> toggle or combo-box for that. The question is how much does the user
>  interaction depend on the chosen algorithm?

My algorithm is quite flexible about that. For instance, the lasso + markers
used for SIOX could be the form of interaction chosen for IFT (I would only
need to select a set of foreground and background pixels as initial
markers), although I think that showing the pre-segmentation and selecting
markers is helpful and more simple. Then, maybe both algorithms could run in
parallel and the results would be somehow merged.

For most cases (highly textured images, similar foreground and background,
variation in illumination, multiple objects, etc.) our algorithm works fine.
However, to solve the transparency issue I am doing some experiments on a
solution which is similar to SIOX. We currently use a pattern classifier to
fuzzy classify all the pixels in order to estimate the arc-weights of the
IFT graph.  Thus, we form a fuzzy map with values between 0 and 1. This map
can be straightforwardly used as an alpha channel, but I'm working on a
piece of code which will allow the user to select, after the hard
segmentation, markers where the fuzzy map values should be considered. Also,
those markers would be used to refine the local fuzzy classification in
order to obtain better values, because our current fuzzy classification
considers global information (the foreground and background markers on the
first iteration).

In a nutshell, first the user would do the binary segmentation and then s/he
would select where soft values should be computed. Therefore, what I mean is
that there will be a nice solution for the transparency problem soon.


Thiago Vallin Spina
MSc student
Laboratory of Visual Informatics
Institute of Computing -- Unicamp
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