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

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

Added a writeFormat() method to Algorithm which must be called by the
write() method of derived classes.

MergeDebevec takes camera response function as an optional input
parameter. Despite being clearly marked as input, this matrix is
overwritten during processing.

This commit adds a temporary matrix to store the log response and avoid
modification of the input.

http://code.opencv.org/issues/4124

avoid possible problems with zero values in tone mapping algorithms (http://code.opencv.org/issues/4020)

significantly improved parallel non-local means by using granularity parameter in parallel_for_ loop. Because the algorithm deals with sliding sums, it's essential that each thread has enough work to do, otherwise the algorithm gets higher theoretical complexity and thus there is no speedup comparing to 1-thread code (at best).

Changed parameter type of fastNlMeansDenoising[Multi][Abs] from std::vector<float> to const std::vector<float>&