CONTENTS FILM LIST (This will be constantly updated):
Blade Runner 2049
Blue Planet II
John Wick 2
I am posting this in its own thread here in the projector forum since I think this information is really useful regarding HDR on projectors specifically since its clear all of us are viewing HDR at a less than ideal peak brightness level, and certainly not at the level intended by the creators of the content. As such our displays have to use tone mapping and gamma curves to arrive at the best possible compromise, and to do that, one must know a little more about the way the content is mastered.
I think this info will be a good reference to see what is really happening with some of the UHD BR titles out there, we will look at the HDR Grading of these films represented in a waveform using the Black Magic Design Davinci Resolve colour grading software. This is the very same software that quite a lot of hollywood films are graded on, and certainly a lot of UHD Blurays are HDR mastered and even remastered in also.
Recently its come to the attention of the general forum that UHD Bluray titles are 'mostly' mastered with black levels down to black 64 on the clipping pattern. Which is 0 nits. Now up until now we assumed based on the metadata associated with the discs that there was a great number of titles, almost half, that are supposedly mastered to 0.005 nits. As such, most of us have been configuring our HDR curves and calibrations to set black clipping to bar 77 as true black, which is 0.005 nits. However we now know that in actual fact, most titles save for a handful so far are really 0 nits. I sought to confirm this in the manner that makes the most sense to me and that is to look at a physical waveform of the film and see what's really going on.
There is a really good spreadsheet which is constantly being updated that contains HDR Metada on a lot of HDR titles, we have mostly been using this unto this point to ascertain certain information on titles.
UHD Bluray HDR Metadata
But I feel we can expand on this, using these waveforms we can also get a really good indication of where most of the real brightness sits on the scale and what it looks like when there are brighter specular highlights etc.
Hopefully we can all use the information in this thread, which will be added to as time goes on, to come to a really good HDR setup personalised for yourself, while targeting peak white levels to suit your own situation, some people may have been using 1000nits as the out of the box clipping level on some Sony projectors for example, some of you may have been using a single 4000 nit calibration. We hope to show here how much content actually exists above 1000 nits, what kind of content it is, and weather some of you with light starved projector and screen combinations may be able to either sacrifice certain things and run lower peak white targets, or at least, make a well informed decision on how to set up your projector for HDR.
This will be a good place to have a look and compare the brighter HDR grades with dimmer titles, some of you may have watched films that you just couldn't understand why the title looked quite dark compared to others, well, we can dive into that here and hopefully if I can get access to said films, we can look at whats really going on in specific scenes.
I will start by submitting a baseline in regards for how to actually read these waveforms.
The waveform in colour grading is a visual representation of the image brightness and colour information from left to right, if you study the waveform next to the image you will begin to get an idea of how the waveform works, the bottom of the scale is black, and the top of the scale is white, or peak output in brightness, the scale all the way at the top or 1023 on the scale is 10,000 nits. No film is mastered to such levels at the moment and probably will not be for quite some time. On the scale you will see 768 also, that is 1000 nits peak output. And for 4000 nits, you will see a faint grey line right at about value 920. Now most of us with either have HDR configured for 768 or 920, most titles are mastered at one of these two values, now what we want to see is what it really looks like with films that say they are mastered to a certain level, do they take advantage of the whole 'container' if you will, or are they falling significantly below the mastering level?
Here is a white clipping chart, you will see from left to right a range in brightness and I have highlighted 1000 and 4000 nits, so you can get an idea when looking at other waveforms where they sit on the scale. You will also see 94 nits on the scale sits right around level 512, this is diffuse white, most of the content in any given frame is going to sit below this point, for eg people faces, clothing etc... if it did not the scene would likely appear to be overly bright and a little intense.
As said the bottom of the scale is black, which is 0 nits, now just above that you will see 0.005 nits, this can be seen on the following image, we should be paying attention to these points, does the waveform fall all the way to the bottom or does a particular film hover just above the bottom closer to 0.005 nits, if so, then that film has a raised black level, and if you are clipping your HDR set-up to Bar 64, or 0 nits black then that film will have a more grey appearance and raised blacks.
On the flip side, we will also see a lot of important content below 0.005 nits on the titles that have true black levels of 0 nits, these waveforms will shot where that content is, and what you are missing. Unfortunately with the state of HDR as it is today, this should ideally not even be a consideration, ALL titles should be black level of 0 nits, the fact that some titles are 0 and some are 0.005 makes it difficult for us to have a one fits all solution for HDR on projectors, and unfortunately we will need either separate user modes for these differing black levels and significantly differing average brightness, or we just choose one or the other and live with it.
NOTE - The below screenshotts will appear to be washed out and not very saturated, this is because they are viewed in log form in this software, since the end display is the one which needs to be in an HDR mode to view it. In fact, those of you viewing the forum with HDR displays will actually be able to see these screenshots if you switch your display to HDR mode. That should be interesting.