Keep in mind that Dolby Vision is exclusive to the 4K Blu ray format, so regular Blu rays wont have it. Finally, you need to make sure your 4K Blu ray has a Dolby Vision scan, because not all of them do. It quite common to find, but a lot of 4Ks have a regular HDR10 scan. HDR10 and Dolby Vision both look great, but Dolby Vision is typically a step above, and it worth using when you have it. Many 4K Blu ray players have Dolby Vision functionality toggled on automatically notably Panasonic...
