Add colour image enhancement element based on Retinex algorithm. Two types
exist, namely basic and multiscale; both are described in this article:
Rahman, Zia-ur, Daniel J. Jobson, and Glenn A. Woodell. "Multi-scale retinex
for color image enhancement." Image Processing, 1996. Proceedings.,
International Conference on. Vol. 3. IEEE, 1996
Visually speaking the result looks a bit funny, but is pretty invariable to
lightning changes, which is good for some applications, like image
segmentation.
https://bugzilla.gnome.org/show_bug.cgi?id=700977
Compile with -DCV_NO_BACKWARD_COMPATIBILITY for now, so that the compat header
doesn't get included, which causes compiler warnings that (it seems) can't be
switched off easily. As a result, we also specify a max. version in configure,
so the build doesn't break if our code doesn't compile against newer opencv
versions any more with that flag.
Override CV_INLINE to avoid 'unused' gcc warnings. GLib will take care of defining
'inline' sufficiently and OpenCV's define isn't good enough to avoid 'unused'
compiler warnings (at least in version 2.1.0).
* Implement pyramid segmentation element
* Make masking optional on edgedetect
* Clean up edgedetect, add element details
* Implemented edge detect element
