- leads to errors due 'const' modifier of getMat() method
- may be non-optimal with non-CPU data storage

This avoids MSVC 19.14.26428.1 to call vectorized __vdecl_cosf4() function with less precision.

- allow 5% of changed pixels with intensity difference <= 1

Refactor decolor (#11035)

* decolor: modernize deprecated headers (math.h -> cmath)

* refactor contrast_preserve.cpp

* refactor contrast_preserve.hpp (add static/const)

* refactor contrast_preserve.hpp (join assignment and declaration)

* refactor contrast_preserve.hpp (format)

* refactor test_decolor.cpp (indent)

* refactor contrast_preserve.hpp (const)

* contrast_preserve.hpp : optimize by minMaxLoc

* fix trailing-whitespace

* fix warning C4267 on VC++ x64
(conversion from 'size_t' to 'int', possible loss of data)

* use cvRound instead of round_num

* decrease indentation of test_decolor.cpp

* remove pow() to optimize

* remove redundant Mat initialization

* optimized cv::decolor by removing vector.push_back

* restored CV_INSTRUMENT_REGION() and original indent

* fix build warnings in contrast_preserve.hpp

* undo refactoring contrast_preserve.cpp/hpp

* clean npr functions of useless initializations (speed-up)

* photo: remove unnecessary code

Found via `codespell`

- removed tr1 usage (dropped in C++17)
- moved includes of vector/map/iostream/limits into ts.hpp
- require opencv_test + anonymous namespace (added compile check)
- fixed norm() usage (must be from cvtest::norm for checks) and other conflict functions
- added missing license headers

Implementation of bit-exact resize. Internal calls to linear resize updated to use bit-exact version. (#9468)

fixed unnecessary reconstruction in seamlessclone by using only the
required rectangular area in input images

  * make test more reproducible

RGB2Lab_f and trilinear interpolation code are in separate branch; cubeRoot(x) instead of std::pow(x, 1.f/3.f)

file with internal accuracy&speed tests moved to lab_tetra branch

Remove unnecessary Non-ASCII characters from source code (#9075)

* Remove unnecessary Non-ASCII characters from source code

Remove unnecessary Non-ASCII characters and replace them with ASCII
characters

* Remove dashes in the @param statement

Remove dashes and place single space in the @param statement to keep
coding style

* misc: more fixes for non-ASCII symbols

* misc: fix non-ASCII symbol in CMake file

There is no cast to wide integer type:
    std::numeric_limits<ST>::max() * std::numeric_limits<ST>::max()

plus minor edits and fixes