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Author Topic: 16 bit dslr  (Read 9054 times)
Fine_Art
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« Reply #20 on: January 21, 2014, 12:16:56 PM »
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If 16 bit capture were available, it could be used in printing as the art of printing is in tone mapping higher dynamic range to what can be printed as Karl Lang explains here. Why else would one resort to HDR imaging in difficult scenes.

Bill

Thanks for the link.

I don't follow, if you already need to tonemap 12 or 14 bit raw to fit into the ~400:1 contrast of the print, why do you need more bits? In theory, I agree more bits give you smoother data for tone mapping, but isn't the current level more than enough for prints?
 
My HDTV has contrast about 4000:1 with gamut (mapped in my colorspider) between SRGB and ARGB. So vivid colors are truly vivid as you would expect. I think the big screen for viewing images is where we need more bits. Get us to 12 or 14 bits with dithering on 12000:1 contrast on 8K then lets look at the framerate destroying 16 bit capture.
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Telecaster
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« Reply #21 on: January 21, 2014, 01:46:29 PM »
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If one wishes to argue that film is more analog since it is a graded absorption in the emulsion I guess that might fly, but the sensor has a specific digital "count" for each and every photon it collects. Voltages are simply a secondary conversion, not the process of absorption within the pixel. It's just the way engineers have (to this point) designed the process, not the actual event. It is quite possible that in the future the process will become digital all the way through and A>D convertors will go the way of... emulsions.

No, the freeing up of electrons (and thus the creation of voltage) is integral to how sensors work. It's not an added-on layer. Future technology may work differently, but this is the tech we've got now. To reiterate: "digital" in the context of current digital cameras refers to the quantization of voltages. The ultimate nature of reality (if there even is an ultimate nature) is way beyond this scope.   Wink

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BTW, quantum mechanics does "respect" the plank length. This should not be confused with thinking that no other interval or system is at play. It's just the theory most consistent with what we think we know… for now… But just as surely as newtonian thinking had to be "refined" by Einsteinian Physics, QM may just be a rest stop too.

Yes, I suspect this is true (QM being the current frontier rather than a final one.)

-Dave-
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ErikKaffehr
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« Reply #22 on: January 21, 2014, 01:52:11 PM »
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Hi,

You can code a wide dynamic range in few bits, that is with Arriflex are doing with S-log. Contrast figures given for screens and projectors are often exaggerated.

Best regards
Erik

Thanks for the link.

I don't follow, if you already need to tonemap 12 or 14 bit raw to fit into the ~400:1 contrast of the print, why do you need more bits? In theory, I agree more bits give you smoother data for tone mapping, but isn't the current level more than enough for prints?
 
My HDTV has contrast about 4000:1 with gamut (mapped in my colorspider) between SRGB and ARGB. So vivid colors are truly vivid as you would expect. I think the big screen for viewing images is where we need more bits. Get us to 12 or 14 bits with dithering on 12000:1 contrast on 8K then lets look at the framerate destroying 16 bit capture.
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Fine_Art
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« Reply #23 on: January 21, 2014, 02:31:38 PM »
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Hi,

You can code a wide dynamic range in few bits, that is with Arriflex are doing with S-log. Contrast figures given for screens and projectors are often exaggerated.

Best regards
Erik


Projectors definitely. There is one bulb. Mostly true for screens as well. I think the difference is on the big HDTVs where they can use multiple light sources for the "dynamic lighting" item in the menu. You are probably still right that they are best case in a black test chamber, not real world. They can however get much brighter than typical computer screens.
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hjulenissen
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« Reply #24 on: January 21, 2014, 02:52:14 PM »
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I don't follow, if you already need to tonemap 12 or 14 bit raw to fit into the ~400:1 contrast of the print, why do you need more bits? In theory, I agree more bits give you smoother data for tone mapping, but isn't the current level more than enough for prints?
>
My HDTV has contrast about 4000:1 with gamut (mapped in my colorspider) between SRGB and ARGB. So vivid colors are truly vivid as you would expect. I think the big screen for viewing images is where we need more bits. Get us to 12 or 14 bits with dithering on 12000:1 contrast on 8K then lets look at the framerate destroying 16 bit capture.
If tonemapping allows one to render a large DR scene using low DR tech (while attempting to minimize artifacts), would not increasing the capture DR (which necessitates higher number of bits at some point) be a worthwhile goal for some situations?

-h
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allegretto
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« Reply #25 on: January 21, 2014, 03:41:42 PM »
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any guy who can imagine a Fat Finger to deal with shutter slap can't be a bad guy so I'll stop the war.

voltage drops are proportional to the detection of photons, and either a photon is there, or it is not. The initiation is digital event; 0 or 1

But i'll give you the last word, any word you want

cheers...  Grin


No, the freeing up of electrons (and thus the creation of voltage) is integral to how sensors work. It's not an added-on layer. Future technology may work differently, but this is the tech we've got now. To reiterate: "digital" in the context of current digital cameras refers to the quantization of voltages. The ultimate nature of reality (if there even is an ultimate nature) is way beyond this scope.   Wink

Yes, I suspect this is true (QM being the current frontier rather than a final one.)

-Dave-
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LKaven
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« Reply #26 on: January 21, 2014, 03:47:27 PM »
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yes, the quantization of light is always digital, and that's my point. Even in your retina.

Though you would be right to suggest that there are reasons to treat many natural processes as embodying computation over discrete domains, there is a practical matter.  Using a von Neumann computer to access natural information requires a step that converts natural information into a form that can be loaded into electronic storage registers.  
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allegretto
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« Reply #27 on: January 21, 2014, 05:40:09 PM »
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well, I know nothing about von Neumann or Harvard designs... Smiley

but I do know retinas. They are well and true digital, in every sense of the term. Nothing analog about it. That's the work of upper neurons grasping at understanding.


Though you would be right to suggest that there are reasons to treat many natural processes as embodying computation over discrete domains, there is a practical matter.  Using a von Neumann computer to access natural information requires a step that converts natural information into a form that can be loaded into electronic storage registers.  
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BartvanderWolf
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« Reply #28 on: January 21, 2014, 06:00:40 PM »
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well, I know nothing about von Neumann or Harvard designs... Smiley

but I do know retinas. They are well and true digital, in every sense of the term. Nothing analog about it.

Hi,

First time I've heard that (I have been told it's an analog photochemical process). Do you have any credible references for that opinion?

Cheers,
Bart
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allegretto
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« Reply #29 on: January 21, 2014, 10:00:20 PM »
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you've been told incorrectly. It is a very much digital process wherein a photon strikes a photoreceptor which yields a cascade of events that reverses membrane potentials. Again recruitment determines the intensity of the sense of the event.

Credible references abound;

http://www.vetmed.vt.edu/education/curriculum/vm8054/eye/rhodopsn.htm - a straightforward review of the chemistry, initiated by a photon. Not an analog process, a conformational change (cis-trans) that is again a 0 or 1. It is cis or trans, not cistrans.

http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Retina/VisualCycle.html - an expansion demonstrating the fact that different colors are sensed by the energy of the given photon

http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Retina/Photoreceptors.html - which further expands upon sensitivity in terms of how many photons it takes to cause a transduced signal to be produced.

All digital processes.

Not you personally, but where is this insistence that light is somehow analog coming from? Light is discrete packets of energy who's speed determines wavelength. When a sensitive receptor is struck by its complimentary photon, the animal's brain sees light. These facts have been pretty much known and agreed to for quite some time. No controversy I'm aware of. Does the characterization of this as an analog process make folks feel better?


Hi,

First time I've heard that (I have been told it's an analog photochemical process). Do you have any credible references for that opinion?

Cheers,
Bart
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Petrus
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« Reply #30 on: January 22, 2014, 12:18:13 AM »
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For photography and projection the light has to pass through a lens. That is actually the bottleneck in trying to achieve better DR, not sensors (we are getting better) or digital calculations (which could be of almost any accuracy already). There is always some dust and internal reflections* which spread the highlights to the full image area turning the blackest black dark grey. This point has been reached already with 14 bit sensors.

For projection better DR could be possibly had with laser projection, just an idea… That would need a lot of computing power and expensive "projector", though.

*) look at the projector lens of just about any projector while it is running...
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hjulenissen
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« Reply #31 on: January 22, 2014, 12:45:18 AM »
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Though you would be right to suggest that there are reasons to treat many natural processes as embodying computation over discrete domains, there is a practical matter.  Using a von Neumann computer to access natural information requires a step that converts natural information into a form that can be loaded into electronic storage registers.  
Some might claim that digital really is analog (since digital information must usually be transmitted or stored using traditional "analog" means). Others might claim that analog is really digital (since the world tends to be granular, at least at the levels of physics where I have some comprehension).

I think such discussions are besides the point. An analog transmission/storage encodes a signal as an "analog", i.e. there is a direct and obvious correspondence between the source variation (i.e. scene brightness) and some modulation of a property (i.e. "bright scene leads to large voltage"). In a digital transmission/storage, the correspondence between source variation and the encoding property is far less obvious (i.e. "scene brightness of X leads to a voltage pulstrain of [+1 -1 -1 +1]"). Some practical consequence of this is that (for digital):
1. Storage/transmission capacity (bandwidth/SNR) can usually be better exploited
2. "errors" can be detected and corrected, provided that they are within bounds
3. Complicated logic is needed, and delay is added

-h
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Vladimirovich
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« Reply #32 on: January 22, 2014, 12:53:34 AM »
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thank you, I totally forgot to eat my daily carrot !
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allegretto
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« Reply #33 on: January 22, 2014, 05:15:50 AM »
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suppose I had a circuit and if one drops a molecule of water on a detector, the gate closes and a potential gets conducted lighting a bulb. Is that digital or analog? Say I had two such circuits... say I had x^y such circuits... A or D?

See, I think your answer is provided in your explanation, but it may not be the one you're thinking of. You note that "analog" is an affect of interplay (intermodulation) of signals to produce the effect. In digital, there is a direct connection between he action and the affect (need not be 1:1 however)

However I think you're right that at some level, everything is digital and it's just a matter of summation and dependent pathways.

Final test... men are digital, women are analog... Wink


Some might claim that digital really is analog (since digital information must usually be transmitted or stored using traditional "analog" means). Others might claim that analog is really digital (since the world tends to be granular, at least at the levels of physics where I have some comprehension).

I think such discussions are besides the point. An analog transmission/storage encodes a signal as an "analog", i.e. there is a direct and obvious correspondence between the source variation (i.e. scene brightness) and some modulation of a property (i.e. "bright scene leads to large voltage"). In a digital transmission/storage, the correspondence between source variation and the encoding property is far less obvious (i.e. "scene brightness of X leads to a voltage pulstrain of [+1 -1 -1 +1]"). Some practical consequence of this is that (for digital):
1. Storage/transmission capacity (bandwidth/SNR) can usually be better exploited
2. "errors" can be detected and corrected, provided that they are within bounds
3. Complicated logic is needed, and delay is added

-h
« Last Edit: January 22, 2014, 05:25:43 AM by allegretto » Logged
BartvanderWolf
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« Reply #34 on: January 22, 2014, 05:40:48 AM »
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you've been told incorrectly. It is a very much digital process wherein a photon strikes a photoreceptor which yields a cascade of events that reverses membrane potentials.

Hi,

You seem to be suggesting that because a photon either strikes, or it doesn't strike, makes it a digital process. If that (probability/statistics) is your train of reasoning, then there would be no analog reality.

Yet, the arrival time of photons is random (Poisson distributed probability), the effect of a photon striking may be inhibited (e.g. lateral inhibition) by other chemicals, and neurotransmitters use electrotonic conduction which produces a constant flow of electric current (see "Graded Response and Release of Neurotransmitters") along the membrane. This turns a variable stream of discrete photons into a very analog process.

Quote
Credible references abound;

Maybe it is the interpretation of that information that is a bit 'debatable'?

Quote
http://www.vetmed.vt.edu/education/curriculum/vm8054/eye/rhodopsn.htm - a straightforward review of the chemistry, initiated by a photon. Not an analog process, a conformational change (cis-trans) that is again a 0 or 1. It is cis or trans, not cistrans.

That's your interpretation. What I read is a "The disintegration of rhodopsin into retinal and scotopsin is progressive", and "The eventual result is release", and "metarhodopsin II, is the agent that ultimately effects the change in the rod membrane's charge". Also, ""Under conditions of impinging light, [...],
Quote
the flow of sodium ions
into the rod outer segment is slowed or stopped. Also "One photon, the minimum quantity of light possible, will cause the movement of millions of sodium ions, because of the catalytic nature of the enzymes and the large surface area provided for them to work".

Not a very binary process at all. Sure, one photon makes a difference (in a Rod), but not always exactly the same, because the result is an analog process flow.

Quote
http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Retina/VisualCycle.html - an expansion demonstrating the fact that different colors are sensed by the energy of the given photon

Another gradual transition process "the activation of rhodopsin during phototransduction isomerizes 11-cis-retinal to the all-trans form, which dissociates from the opsin in a series of steps called "bleaching" ". Dark adaptation also causes a continuously variable sensitivity, not digital at all.

Quote
http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Retina/Photoreceptors.html - which further expands upon sensitivity in terms of how many photons it takes to cause a transduced signal to be produced.

Indeed, Rods have more photopigment and have a high (single photon) sensitivity but lower temporal resolution, more signal integration. Cones have lower sensitivity, higher temporal resolution and less signal integration. Both are not digital at all.

Quote
All digital processes.


Really? It seems to be quite the opposite.

Quote
Not you personally, but where is this insistence that light is somehow analog coming from?
 Light is discrete packets of energy who's speed determines wavelength.

Actually, the speed of light is constant (in vacuum), Photons can be considered to exhibit both wavelength, and energy characteristics. That's known as the wave-particle duality of light. Waves are not digital, and even energy particles fluctuate as (valence) electrons are knocked in and out of the (outer) shell of atoms.

Cheers,
Bart
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hjulenissen
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« Reply #35 on: January 22, 2014, 06:19:00 AM »
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suppose I had a circuit and if one drops a molecule of water on a detector, the gate closes and a potential gets conducted lighting a bulb. Is that digital or analog? Say I had two such circuits... say I had x^y such circuits... A or D?
My point: who cares? I believe that everything "digital" in communication or circuits can be explained by "analog" fundamentals. A cpu can be analysed using R and C and L and transistors and wires. It just gets very messy and you quickly get to the stage where it is impossible to calculate the result numerically (or comprehend anything intuitively).

"Digital" is (in my view) best seen as some sort of man-made abstraction on top of "analog" that lets us do things that would otherwise be very impractical. Whether that "analog" thing at the bottom is really continous or granular is for the majority of people and cases utterly irrelevant. Even if it was truly continous, everything outside of a mathematicians whiteboard is troubled by measurement noise, meaning that observations of a signal or system contains some uncertainty (be it "noise" or "quantization" or "photons" or whatever).

-h
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BartvanderWolf
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« Reply #36 on: January 22, 2014, 06:30:40 AM »
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"Digital" is (in my view) best seen as some sort of man-made abstraction on top of "analog" that lets us do things that would otherwise be very impractical. Whether that "analog" thing at the bottom is really continous or granular is for the majority of people and cases utterly irrelevant.

Indeed. It's the inevitable integration over time (unless we travel at the speed of light) that makes random discrete phenomena analog, continuously variable. Discrete quantization then becomes a tool, a useful abstraction for statistical calculation.

Cheers,
Bart
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Fine_Art
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« Reply #37 on: January 22, 2014, 11:31:58 AM »
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If tonemapping allows one to render a large DR scene using low DR tech (while attempting to minimize artifacts), would not increasing the capture DR (which necessitates higher number of bits at some point) be a worthwhile goal for some situations?

-h

Yes, if it is necessary to make the whole capture in one shot. That is a completely different argument(position). It has nothing to do with fitting the data properly in a print. You could use 3 8 bit shots to gather the data. So the question is do you shoot when DR is high as in midday? Most people try to shoot when the light is directional which shows off surface features. If you need to shoot the sun in a sunset shot for example, you do not expect the sun not to clip. Many classic prints, for example Ansel Adams, used a lot of dodge/ burn to increase the contrasty look further wiping out DR detail in the print from what film could do.

We can generalize to the idea that it is always best to capture as much detail/ data as the scene allows. My question is can someone see in a print the difference between tonemapped from 12 bit vs from 16 bit? 
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hjulenissen
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« Reply #38 on: January 22, 2014, 12:21:32 PM »
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Yes, if it is necessary to make the whole capture in one shot. That is a completely different argument(position).
When talking about sensor DR I am naturally talking about making the capture in one shot. Multi-capture DR enhancement (as used in "HDR" photography) is an ergonomic and artistic kludge that we only use because of limitations in the single-capture DR.
Quote
So the question is do you shoot when DR is high as in midday? Most people try to shoot when the light is directional which shows off surface features. If you need to shoot the sun in a sunset shot for example, you do not expect the sun not to clip. Many classic prints, for example Ansel Adams, used a lot of dodge/ burn to increase the contrasty look further wiping out DR detail in the print from what film could do.

We can generalize to the idea that it is always best to capture as much detail/ data as the scene allows. My question is can someone see in a print the difference between tonemapped from 12 bit vs from 16 bit? 
If they can see the difference between a multi-exposure synthesized image that has been quantized to 12 vs 16 bits prior to tonemapping, then we can assume that it is possible to see the difference between a "true" 12-bit and 16-bit sensor.

-h
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allegretto
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« Reply #39 on: January 22, 2014, 12:59:14 PM »
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oh my, much here. I can see you'd like to debate this, but there is no need

First, either a membrane potential exists or it has collapsed. That there are different ranges of sensitivity in different cell populations due to supressor or excitatory activity is a fact. But the truth is that at some point the potential collapses and conduction occurs or it does not. Again, about as binary as possible. This is true of a great many biologic processes. Recruitment of responses is what gives the event it's "analog" appearance. let's take an analog (pun intended) in an electronic circuit. Suppose we have a circuit with an instruction to not conduct until the gate potential (call it what you like) reaches 3 mv. At 3 mv it closes and sends a blip. Would you argue that this is a digital or analog event? Certainly differing blips being conducted at different potentials could summate and transmit an analog signal, but would you argue that the single circuit is analog?

If you look macro enough, the process can be analog-appearing. But the potential is the key to the information being conducted or not. And if not conducted, it is not detected. Doesn't mean it does not exist, it is simply below threshold. In your rhodopsin example you introduce the variable of "recovery" which certainly affects discharge. But it is the discharge that determines detection of information, not the amount of rhodopsin.

As far as the concept of wave/particle duality and "c", well perhaps this will help; http://www.living-universe.com/home/7-Photon-Energy.html. Photons do have mass and are not waves. Duality is an explanation, but not a reality.

Likewise, wavelength/speed is a by-product of SR and not really what I thought we were talking about. However, "c" is constant in it's own frame of reference, but not to an outside observer. In laboratories workers have "slowed" photons to extremely low apparent velocities, but no one told the photon so it happily goes on not realizing what some lab rats think, such is SR. Further, your observation about electron states and "color" are addressed as well. Note the photon retains its characteristics even when interacting with an atom. We have learned a great deal about electrons since 1905. They are not what we used to think. but again, this was not my point.

So one more time, will note that a retinal cell either fires or it doesn't. If it doesn't fire, the visual cortex receives no signal from it and it remains dark. This is information however (being dark), so it reveals the true binary nature of a retinal cell.I consider that digital. You may not I suppose, but that isn't how many of us view it.

e
Hi,

You seem to be suggesting that because a photon either strikes, or it doesn't strike, makes it a digital process. If that (probability/statistics) is your train of reasoning, then there would be no analog reality.

Yet, the arrival time of photons is random (Poisson distributed probability), the effect of a photon striking may be inhibited (e.g. lateral inhibition) by other chemicals, and neurotransmitters use electrotonic conduction which produces a constant flow of electric current (see "Graded Response and Release of Neurotransmitters") along the membrane. This turns a variable stream of discrete photons into a very analog process.

Maybe it is the interpretation of that information that is a bit 'debatable'?

That's your interpretation. What I read is a "The disintegration of rhodopsin into retinal and scotopsin is progressive", and "The eventual result is release", and "metarhodopsin II, is the agent that ultimately effects the change in the rod membrane's charge". Also, ""Under conditions of impinging light, [...],  into the rod outer segment is slowed or stopped. Also "One photon, the minimum quantity of light possible, will cause the movement of millions of sodium ions, because of the catalytic nature of the enzymes and the large surface area provided for them to work".

Not a very binary process at all. Sure, one photon makes a difference (in a Rod), but not always exactly the same, because the result is an analog process flow.

Another gradual transition process "the activation of rhodopsin during phototransduction isomerizes 11-cis-retinal to the all-trans form, which dissociates from the opsin in a series of steps called "bleaching" ". Dark adaptation also causes a continuously variable sensitivity, not digital at all.

Indeed, Rods have more photopigment and have a high (single photon) sensitivity but lower temporal resolution, more signal integration. Cones have lower sensitivity, higher temporal resolution and less signal integration. Both are not digital at all.
 

Really? It seems to be quite the opposite.

Actually, the speed of light is constant (in vacuum), Photons can be considered to exhibit both wavelength, and energy characteristics. That's known as the wave-particle duality of light. Waves are not digital, and even energy particles fluctuate as (valence) electrons are knocked in and out of the (outer) shell of atoms.

Cheers,
Bart
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