Let's delve deeply into color volume and what it means

[Penton-Man]

Originally Posted by Robert Zohn

The human visual system can see 7 stops of contrast, but the range varies based on the ambient light conditions....

Robert, there is no clear agreement as to what the simultaneous (instantaneous or static)
dynamic range of human vision exactly is (see next to the last paragraph of the Introduction here - https://pdfs.semanticscholar.org/cad...ab6b1c0c0d.pdf for references), but I think most would consider that 7 stop figure to be low balling it. These days most estimate it ranges from 10-14 stops (1000:1 to 16:000:1 contrast ratio) with consensus being ~ 12 stops, for static (instantaneous) dynamic range of the human visual system (HVS)….



With time, i.e. allowing time for papillary response and retinal (bleaching) adaptation (dark
adaptation taking longer than bright, on the order of tens of seconds to minutes), altogether the human visual system is capable of about 24 stops……



For those desiring to take a deeper dive, these are good introductory lectures to the HVS (for the current contrast discussion concentrate on Lecture #2,' the csf')… http://www.jennyreadresearch.com/201...visual-system/

by Jenny who has spoken at previous professional HDR workshops.

[Robert Zohn]

Originally Posted by Penton-Man

Robert, there is no clear agreement as to what the simultaneous (instantaneous or static)
dynamic range of human vision exactly is (see next to the last paragraph of the Introduction here - https://pdfs.semanticscholar.org/cad...ab6b1c0c0d.pdf for references), but I think most would consider that 7 stop figure to be low balling it. These days most estimate it ranges from 10-14 stops (1000:1 to 16:000:1 contrast ratio) with consensus being ~ 12 stops, for static (instantaneous) dynamic range of the human visual system (HVS)….

Thanks Penton-Man. I shortened your post for brevity.

I was taught that the human visual system can see up to 7 stops in any given fixed APL and ambient light conditions. I also understand that there is no clear agreement on the static dynamic rage we can resolve, but my teaching is also the thinking of Wikipedia where they say "The retina has a static contrast ratio of around 100 000:1 (about 6.5 f-stops)"

Regardless if it's 7 stops or 10 stops or even 12 stops we can not see the full range of HDR's specular highlights that can easily hit 14 stops. Our brain clips the specular highlights.

[Penton-Man]

Originally Posted by Robert Zohn

my teaching is also the thinking of Wikipedia where they say "The retina has a static contrast ratio of around 100 000:1 (about 6.5 f-stops)"

Sometimes using Wikipedia is not that great of an idea.

Originally Posted by Robert Zohn

Regardless if it's 7 stops or 10 stops or even 12 stops we can not see the full range of HDR's specular highlights that can easily hit 14 stops. Our brain clips the specular highlights.

Hmm, interesting assertion, for when I say human visual system (HVS) above, I’m actually referring not only to the eye, but all the neural pathways including from the optic nerve distally to areas of the cerebral cortex.

Despite occasionally joking around with topics like flatulence in order to encourage people to learn something new, I’m also a wee bit familiar with the brain and its connections too, see the brain hyperlink, i.e. the human connectome project.

Do you have a citation (on the order of pubmed, e.g. https://www.ncbi.nlm.nih.gov/pubmed/16102542) which had to pass through at least some sort of independent editorial review panel in order to get published in a scientific journal rather than something from the layman’s press to back up that clipping level assertion?

[Deciazulado]

Originally Posted by Robert Zohn

Thanks Penton-Man. I shortened your post for brevity.

I was taught that the human visual system can see up to 7 stops in any given fixed APL and ambient light conditions. I also understand that there is no clear agreement on the static dynamic rage we can resolve, but my teaching is also the thinking of Wikipedia where they say "The retina has a static contrast ratio of around 100 000:1 (about 6.5 f-stops)"

Regardless if it's 7 stops or 10 stops or even 12 stops we can not see the full range of HDR's specular highlights that can easily hit 14 stops. Our brain clips the specular highlights.

Robert 7 f-stops (128:1) (actually 7 and a third, 160:1) is the range of the average pictorial scene according to for example the Kodak/RIT photography text books I used to read, and so, photographic systems were optimized for that, but the eye capacity exceeds the average scene plus an eye's pupil like Penton's graphic shows can open and close a few f-stops on it's own automatically (dynamic HDR? ) from moment to moment depending on where you focus when seeing things.

And so you see how things can go awry on wikipedia, 100,000:1 is actually 16.6 f-stops, not 6.5, maybe a typo ate the figure to the left of the 6

10 f-stops (1000:1) which many LCDs have gives the impression of grey "letterbox" bars for me.

With the PQ HDR contrast EOTF (or actually displays with very high contrast) (more than 10) you probably can exceed the simultaneous contrast if you wanted to, maybe like the 3-D ping pong effects to dazzle, or if for example you represented a night or dark interior scene luminance faithfully (which is one of the features of a fixed luminance EOTF like PQ for example) and then changed to a sunny outdoor scene instantly (just like going to a cinema at mid day and after 2 hours of darkness you go out to the exit that opens directly to the parking lot! (But your eyes tho hurting adapt pretty quickly). The good thing is we're achieving this (or near achieving this) so artistically it can be done if desired. (Reproduce real luminances faithfully). So on one hand you can achieve exceeding the eye momentarily.

On the other hand, now another thing I remember from those books was, that when photographic material tone reproduction was tested extensively, and exact faithful scene tone reproduction was achieved, subjects actually didn't prefer that, and that a close but slightly curved tone reproduction curve (S) was preferred as giving the most pleasing reproduction . And then it said that of course the aim of photographic imaging systems was to do images with preferred tone reproduction.

[Penton-Man]

Originally Posted by Penton-Man

dynamic range of human vision exactly is (see next to the last paragraph of the Introduction here - https://pdfs.semanticscholar.org/cad...ab6b1c0c0d.pdf for references)....

Full (up to date) reference disclosure regarding the primary author of that ^ paper….https://www.linkedin.com/in/timo-kunkel-bb021917, he, like Rob A. who I referenced in a prior post somewhere on this forum has also spoken at the HPA retreat .