Http:/prerelease. pravoved. com. ru/newquestion

There is interest in detecting these rivers automatically, so that they can be avoided (probably by manual editing of the text). Raphink is making some progress at the TeX level (which only knows of glyph positions and bounding boxes), but I feel confident that the best way to detect rivers is with some image processing (since glyph shapes are very important and not available to TeX). I have tried various ways to extract the rivers from the above image, but my simple idea of applying a small amount of ellipsoidal blurring doesn't seem to be good enough. I also tried some Radon Hough transform based filtering, but I didn't get anywhere with those either. The rivers are very visible to the feature-detection circuits of the human eye/retina/brain and somehow I would think this could be translated to some kind of filtering operation, but I am not able to make it work. Any ideas?

https://www.google.ru/#hl=ru&newwindow=1&safe=off&output=search&sclient=psy-ab&q=%D0%BF%D0%BE%D0%B3%D0%BE%D0%B4%D0%B0&oq=%D0%BF%D0%BE%D0%B3%D0%BE%D0%B4%D0%B0&gs_l=hp.3..0l4.2597.4358.0.4669.8.7.1.0.0.0.256.1437.0j4j3.7.0.eappsweb..0.0...1.1.4.psy-ab.zsilv_IVxP4&pbx=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.42768644,d.bGE&fp=c20e43a6135619db&biw=1366&bih=624

vk.com

http://ru.wikipedia.org/wiki/%D0%97%D0%B0%D0%B3%D0%BB%D0%B0%D0%B2%D0%BD%D0%B0%D1%8F_%D1%81%D1%82%D1%80%D0%B0%D0%BD%D0%B8%D1%86%D0%B0

To be specific, I'm looking for some operation that will detect the 2 rivers in the above image, but not have too many other false positive detections.