1. Explain grayscale input still read as three channel
2. Fix typo
3. Add more details to image match explanation to include the use of masks

removed binary

update

fix for #6598

All of these: (performance) Prefer prefix ++/-- operators for non-primitive types.
[modules/calib3d/src/fundam.cpp:1049] -> [modules/calib3d/src/fundam.cpp:1049]: (style) Same expression on both sides of '&&'.

Allow configuration of the square size in stereo_calib.

https://github.com/Itseez/opencv/issues/6456

responses must be float, else we trigger an assertion in line 150

Added some asserts.

  - previously BB was ignored for first frame, now masks analysis area
  - also allow real-time feedback of processing

Added new test (separating two points)

Also fixed documentation, refactored sample.

Without fixes after 68 line (img1_filename = parser.get<std::string>(0);) OpenCV Error:
./stereo_matching im0.png im1.png --max-disparity=16 --blocksize=17

OpenCV Error: Bad argument (undeclared position 0 requested) in getByIndex, file /home/entodi/opencv/modules/core/src/command_line_parser.cpp, line 169
terminate called after throwing an instance of 'cv::Exception'
  what():  /home/entodi/opencv/modules/core/src/command_line_parser.cpp:169: error: (-5) undeclared position 0 requested in function getByIndex