I have posted a color target here today. I am matching the UHD Samsung monitor to what I know the picture should be like from years of experience with it. On LI in the Safari browser it is a good match because the SAFARI browser ignores the color profile attached to the picture and uses its monitor profile. In Firefox the colors are slightly darker because FIrefox reads the color profile of the picture.
See how the colors look in your browser. Let me know.