Change the gstretinex.c file to cpp and add it into Makefile.
It is necessary to migrate the retinex element to C++,
because new Opencv API leaves obsolete functions like cvSmooth.
This element uses this function.
You can see in this link:
http://docs.opencv.org/modules/imgproc/doc/filtering.html?
highlight=cvsmooth#void cvSmooth(const CvArr* src, CvArr* dst,
int smoothtype, int size1, int size2, double sigma1, double sigma2)
https://bugzilla.gnome.org/show_bug.cgi?id=754148
If old opencv1-style legacy include directory is available,
this change becomes purely cosmetic (maybe will compile a bit faster).
It becomes an FTBFS fix when opencv1-style include directory is missing
(possibly because opencv package maintainer decided not to pack it).
https://bugzilla.gnome.org/show_bug.cgi?id=747705
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
