compare_table           Compare values within tow arrays or matrices.
                        Helper function for 'locate_ndl_in_hay()'.
count_val_freq          Helper function for 'compare_table()'.
get_os                  Get OS name
hay2needle              Cut off a part of image from a whole image.
image2gray_matrix       Convert cimg class into grayscale xy matrix.
                        Helper function for 'locate_image()'. Use
                        grayscale to Speed up and to simplify code.
index2xy                Convert array index into xy location in matrix.
                        Helper function for 'locate_ndl_in_hay()'.
install_screenshot      Install command line screenshot for Windows.
is_all_same             Helper function for 'locate_ndl_in_hay()'.
locate_image            Locate needle image position on a screenshot
                        image.
locate_ndl_in_hay       Locate needle image matrix position in a
                        haystack_image matrix. Helper function for
                        'locate_image()'.
screenshot              Take a screenshot.
screenshot_exists       Find screenshot exec file.
xy_pos                  Get xy position of a value in a matrix Helper
                        function for 'locate_ndl_in_hay()'.
