How are movies that end up on 4k blurays being converted to HDR? in General Discussion Posted April 20 1 hour ago, Tyler Purcell said: You can turn Rec 2020 into Rec 709. You can't turn Rec 709 into Rec 2020. Once you've compressed the image, you can't get the missing information back. But if the UHD version has an extra layer of blacks for more contrast, then I guess it wouldn't be as simple as a LUT. You'd have to do some tone mapping I guess (for going from Rec 2020 to Rec 709)?