modified:   modules/line_descriptor/perf/perf_matching.cpp
	modified:   modules/line_descriptor/test/test_matcher_regression.cpp

	modified:   modules/line_descriptor/perf/perf_matching.cpp
	modified:   modules/line_descriptor/test/test_matcher_regression.cpp

- read image as 1-channel grayscale
- 3 trackers to control function parameters
- K allowed to go to negative values (usually to detect black text on white bg)

- no for-loops
- support all thresholding types
- support any input image depth
- add Doxygen comments

otherwise we get a failed assertion from OutputArray::create