HDR WTF ??

[gilesgoat]

It's a deep hole, as I discussed above.

Basically you have to control as much as possible of the whole process from the equations used to render original images on the screen, any postprocessing, the transfer from the computer to the display device, the display device's processing, the appearance on a panel whose characteristics vary both at manufacture and further with age, then the transport to the eye, which includes the effects of the ambient environment and even the history of what the eye has recently been exposed to.

Every stage has a complex mess of nonlinear functions, most critically of which there are several clamp and step points (e.g. how many values are there inside the computer or on the display to represent the pixel or what the maximum value that can be handled is).

The core of HDR is perhaps well summed up as "better matching those steps and clamps to reality". Increased maximum brightness and higher colour depth are "easy" things to throw at the problem and definitely give you More HDR, but it's not necessarily a big step towards fixing the real underlying problems.

Quite a number of things I've seen "HDR" show results that .. are questionable .. are they really "more natural as we should see them ?" .. or it's more "an idea of what we think we should see" ?

To be honest my current problem is I have something in SRGB space that I want to look "as close as possible to how it is on SRGB" to a device that outputs "natively" in P3-D65 I may have found the correct transfer functions but I may also have found a way to have that automagically done it for me.

( turns out there are a couple of matrices to go from SRGB to can't remember what to P3-D65 plus some nonlinear RGB transfer functions but I may have found 'something' that will do it all for me ).

My problem with R10G10B10A2 is that 'A2' that leaves only 2 bits for alpha so we can't natively render in that ( that would still probably "fuck a bit" all the colours / textures ) because we need at least 8 bits of alpha for all the color blending shit we do so the only way I think is to render into SRGBA8888 and then convert.

And to be honest "I don't have much time nor really the expertise to start messing with HDR and try to fine tune results" even and especially because I can never be sure what "user X" will ever see with its "HDR TV" ...

[GoatFoam]

The problem is the displays.

Using exposure bracketing, fancy cameras and lighting simulations we can create images which faithfully capture several orders of magnitude of dynamic range. Then we have to find a way to display them on devices with much, much lower dynamic range.

So what do you do?

At the highest level the two options are to squash the dynamic range globally so you get something with most of the "feel" of the image but loses fine detail, or to preserve the fine detail at the expense of global consistency.

The unnatural "HDR" images that used to plague photography forums are generally a result of people going for a "local" operator and messing around with the sliders.

Screens are a lot better than they were, but the really good stuff never took off in the consumer space to the extent I thought it would have by now.

[Rhythm]

Screens are a lot better than they were, but the really good stuff never took off in the consumer space to the extent I thought it would have by now.

We'd need standardisation before that happens, and it just isn't happening in any meaningful way. There's already a world of difference between the effects that FALD, MicroLED & OLED can offer. Then there's the lack of proper agreement of standards (HDR400 etc). Then we have Dolby stepping in, fucking it up for everyone by adding Dolby Vision into the mix (which exists to try to compensate the shitty initial batch of HDR we saw).

The whole thing is a mess. It puts me in mind of that addage that "no internet is better than unreliable internet". I often find myself watching SDR content on HDR-capable screens because the actual experience you get with HDR ranges from *amazing* to "what the fuck were they thinking?".

It's the CD issue of Dynamic Range Compression (Loudness Wars) all over again

[zip accident]

The problem is the displays.

Nope. That's the easy sector of the problems. The really hard part is that no two eyes are identical, and neither are any two brains.

[Dio]

It's everything. Saying it's just one problem just makes people disappointed when they buy a better monitor or another logo and it still looks off. And it's likely one of those things where we've got used enough to how it looks that anything different looks worse. Possibly even when it's a genuine improvement (look at all the nonsense about HFR, which is definitively better than the horror of multistrobed 24fps but some people just refuse to accept they've acclimatised to something awful).

[gilesgoat]

I *SUSPECT* we'll end up with "the Hi-Fi reverse baththub curve problem" .. "what people expects when you talk HDR ?" .. "incredibly dark blacks and striking light effects ?" .. "PUMP up the BASS, PUMP up the treble, flat the midranges" .. OOH LOOK it's SHINY, IT'S HDR !!

Also what I call "the CSI effect" ( not THAT one, the other one ) .. because I think "CSI" popularized that "style" .. you tell me when you go in ANY natural scene, with some exceptions of course, and you see purple lights .. orange lights .. ULTRA SATURATED HUEs .. colours all over the places popping up like someone trimmed the "CHROMA" "to the max" ?? ???

And then "let's throw this in the middle too" .. SOMEONE EXPLAIN ME .. "what is really SO SPECIAL in a MEDICAL BW MONITOR to see X-rays/MRI/CT scan pics" .. that makes such monitors cost like 20K .. 30K .. "what kind of greyscales they have" ??????!!??

Or it's a case of "it's MEDICAL, let's pump the price 100X" ...

[edit] - I mean "shit" like this one : https://doubleblackimaging.com/

[Dio]

They need to be ultra-precisely calibrated so they always look exactly the same. Down any other route lies very serious lawsuits - there needs to be no possibility of blaming the monitor for someone dying.

[GoatFoam]

The problem is the displays.

Nope. That's the easy sector of the problems. The really hard part is that no two eyes are identical, and neither are any two brains.

I see the point but mostly disagree.

In the limit, if you have a sensor or simulation that captures light intensity over a full spectrum and a display that perfectly reproduces it then you effectively have ground truth. Of course the displays don't exist.

If you can't reproduce ground truth then you have to display something else. What that something else is will involve trade-offs. My point is that you have to choose what to prioritise, and that as the display is currently the most limited part of the pipeline it's where the most information is lost.

What human eyes and brains prefer is mostly a calibration problem unless the human in question is lucky enough to have extra primaries.

I have radically different colour vision in my left and right eye, so I can pick and choose what I see by winking '-)

[gilesgoat]

This is the BEST I READ SO FAR ...

HDR (High Dynamic Range) TV standards describe a display that is yet to exist; one that produces 10,000 nits of light intensity and colors that only the very latest laser technology screens can display. Therefore, every HDR screen is a compromise and it is up to the manufacturers to decide how to approach that compromise.

.. now we are talking ..

[Rhythm]

This is the BEST I READ SO FAR ...

HDR (High Dynamic Range) TV standards describe a display that is yet to exist; one that produces 10,000 nits of light intensity and colors that only the very latest laser technology screens can display. Therefore, every HDR screen is a compromise and it is up to the manufacturers to decide how to approach that compromise.

.. now we are talking ..

Isn't that kind of the story with all standards? "With this standard we could, in theory, reach these goals".

But yeah, HDR is mega-fucked and arseholes like Dolby getting involved aren't helping in the slightest

[Little stoned kiwi]

I'm watching Five Nights at Freddy's and it's not a good time.
Black, dark, night-time is the norm and looks like garbage on my old kit.

It makes me think this is the place for HDR. It also makes me think post-production efforts could be lazily farmed out to it.

[Deckard]

Barry in 4k HDR on my LG TV is the best picture quality I have ever seen - even hubby commented on it....

[WiteWulf]

Barry as in the Bill Hader thing?

My goto demo for HDR is Pacific Rim, it's so colourful and loads of high-contrast stuff in it that really makes an OLED screen pop.

Interestingly, plenty of testing in recent years has shown that people respond much better to a good HDR presentation than they do to the jump from 1080p to 2160p. 4k really isn't all that important, but good dynamic range content on a display that can reproduce is it great.

[Deckard]

Barry as in the Bill Hader thing?

My goto demo for HDR is Pacific Rim, it's so colourful and loads of high-contrast stuff in it that really makes an OLED screen pop.

Interestingly, plenty of testing in recent years has shown that people respond much better to a good HDR presentation than they do to the jump from 1080p to 2160p. 4k really isn't all that important, but good dynamic range content on a display that can reproduce is it great.

yeah the Bill hader thing - I dont know what they have done to the visuals but it pisses on anything on Apple tv or netflix for the HDR - some scenes its just incredible...I suppose it should be for 6gb for 27 mins of video....

[WiteWulf]

Oof, that’s crazy high bitrate for TV! That’s 20mb/s: most streamed movies are more like 15mb/s, with high quality Blu-ray 80-100mb/s and most rips/encodes or low quality retail discs ~40-50mb/s

The BBC’s early test iPlayer UHD streams were around 30mb/s, but they’ve dropped to 15-20 now

Might have to have a look just to see what it’s like.