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Author Topic: Is accurate color possible in non-standard light?  (Read 13884 times)
hjulenissen
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« Reply #40 on: October 04, 2013, 07:50:13 AM »
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If I look on reality through a window in a dark room there's no difference from standing outside. You'll still see that the arctic dusk light is blueish indeed. If the room is lit with ordinary room lights you'll experience the brain's "evening out" effect, you'll see that the outdoor light really is blue and the indoor is much much warmer but it does not really look strange. If you take an indoor-white-balanced photograph of the same you'll see the outdoor scene is much more extremely blue than it was to the eye, and if you adjust the WB so the outdoor look realistic the indoor looks wrong, so in that case you'll need dual white balance, and this is a problem architecture photographers often need to relate to.

Let's say we make a print with identical spectral characteristics, we would have to have it a backlit print to make it work. I think it would be experienced as looking out through the window. To make a regular print that works in ordinary display conditions you may need to make some adjustments, probably even it out a bit, ie maybe reduce the blueishness of the light slightly, but then we're in the fine-tuning phase.
If you make sure that the spectral characteristics of the print subject to whatever the lighting is inside the cabin matches (as closely as possible) the spectral content measured previously, should you need to do any tinkering? Should you need for the paper to be backlighted?

-h
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torger
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« Reply #41 on: October 04, 2013, 08:07:54 AM »
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Some philosophy:

Working with color and decide how to relate to it is an ongoing process for me. I know I don't want to end up like a photographer that thinks for a true artist anything is allowed and pull and push contrast and saturation to extreme levels, and on top of that say "I don't use photoshop much". I know many do, some very commercially successful, and good for them, but that's not how I want to develop my own photography.

I want to have some documentary aspect in my pictures, an honesty if you like. Even if it costs me a facebook like or two Wink. I've put quite a large effort in how to use dynamic compression techniques for backlit scenes that need it and still retain a realistic look, and I think I've found quite good techniques for that (and even developed own software for that which I hope to be able to release soon). Realistic color rendering is an ongoing challenge though, and it's interesting to see that so little has been done. Is it because no-one wants it, because it's difficult or impossible to get meaningful results, or because no-one has had the time to do it yet... I'm not sure.

I don't believe in that healthy eyes see colors vastly different and thus any kind of measurement or matching would be meaningless as some imply. Current color models assume that we all see colors in a similar way. However different photographers with the same goal of realism still have different taste in how to adapt colors for a print, and different taste of how to fine-tune to make something look realistic. For example exactly how much should we reduce haze on that distant mountain, how much to compress highlights and adjust contrast. Some may think that the latitude of those post-processing changes is so large that some sort of "reference starting point" would be meaningless. I do believe that absolute accuracy is unnecessary for these reasons, but I also do believe that there could be better techniques than exist today.
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torger
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« Reply #42 on: October 04, 2013, 08:16:51 AM »
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If you make sure that the spectral characteristics of the print subject to whatever the lighting is inside the cabin matches (as closely as possible) the spectral content measured previously, should you need to do any tinkering? Should you need for the paper to be backlighted?

I think it becomes quite theoretical as I suspect that there are no techniques that are remotely close to replicate the spectral characteristics. But if you could and the walls in the cabin would not reflect any light, no you should not need to do any tinkering, it would look like looking out a window from a dark room, and the eye/brain would make the same adaptations as it would for the real scene. Ie I'm quite sure that it's 2D would not make any significant difference in color experience.
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digitaldog
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« Reply #43 on: October 04, 2013, 08:19:02 AM »
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torger you seem very knowledgeable about the subject which makes me wonder why you posed the question in the first place?
Yes, this seem to be a thread moving into an area where one is searching for a solution in search of a problem.
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Andrew Rodney
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torger
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« Reply #44 on: October 04, 2013, 08:51:47 AM »
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torger you seem very knowledgeable about the subject which makes me wonder why you posed the question in the first place?

I've learnt a lot in a quite short period, and that may give you a bit of patchy knowledge, so I asked to see if there was any technique I did not know about and is missing out on. I also wanted to test if my assumption was true, ie that the current color models is not designed to solve these type of problems. And to see how other users are dealing with it. And the result seems to be that no there was no other technique, but the efficiency of manual WB live view on site matching is worth evaluating some more, and yes the assumption was true (color models are not designed to solve these type of problems), and most users deal with it by not thinking it is a problem.

I think the major disagreement we see in the thread is about if there actually is a problem or not, and in the extent there is if it's meaningful (or even possible) to solve or not. I thank everyone for their input.
« Last Edit: October 04, 2013, 08:54:14 AM by torger » Logged
kers
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« Reply #45 on: October 04, 2013, 11:07:36 AM »
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Correct me if i am wrong  Huh
but I thought  that if the light does not come from a black warm body- it does not have a complete spectrum of colours so in that light you cannot reflect all colours.

examples are TL-tubes and laserlight.

of course it depends on the definition of 'accurate colour' .
But it is clear that red laserlight shining on a blue subject will never be reflected as blue. So cannot be reproduced in a photograph as blue.
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Pieter Kers
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« Reply #46 on: October 04, 2013, 11:45:17 AM »
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Correct me if i am wrong  Huh
but I thought  that if the light does not come from a black warm body- it does not have a complete spectrum of colours so in that light you cannot reflect all colours.

Hi Pieter,

That's correct. Which begs the question, in what way does the arctic light differ from more regular daylight, which is seems to do. I'm a bit puzzled as to why the human eye, apparently, is not capable to compensate which thus creates a desire to also introduce a cold color cast in rendered images.

BTW, I am aware of the existence of blue ice.

Cheers,
Bart
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Tim Lookingbill
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« Reply #47 on: October 04, 2013, 12:05:29 PM »
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...Realistic color rendering is an ongoing challenge though, and it's interesting to see that so little has been done. Is it because no-one wants it, because it's difficult or impossible to get meaningful results, or because no-one has had the time to do it yet... I'm not sure.


As a former photo realistic styled painter, I can answer that with some authority with regard to emulating a 3D scene on a 2D surface and it is has a lot to do with mimicking the spectral reflectance "effect" we view in a real scene with our eyes bombarded with a huge surround of light compared to viewing within the reflective/transmissive environment of a flat, focused framed surface and what it does to our perception of the "real" scene on a display and print from an emotional aspect. There's a huge change to the perception many aren't and/or can't be aware of.

If we were to actually duplicate exactly what our eyes sees normally without the frame of a viewfinder, it looks rather dull and low contrast if you're REALLY honest with yourself on making that match. You can do it quite easily by creating a diorama scene of objects arranged together next to your display lit by a full spectrum light source such as your window or Solux lamp, photograph it in Raw and view it on your display. In my experience I can get it to look exactly as the diorama appears, but as for a desirable scene you'ld want to view for any length time? Not a chance. Pretty dull looking.

Can't do this with landscapes of course because you have to rely on memory of the scene which isn't exact at all. Pleasing is all one has left to render it as faithfully as possible and still maintain some emotional connection first established when tripping the shutter.

Could you post a sample image of a scene you think has "realistic" colors? That way we all can be on the same page on what you mean by this term which may not be what we consider as realistic at all.
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Floyd Davidson
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« Reply #48 on: October 04, 2013, 12:16:00 PM »
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I'm a bit puzzled as to why the human eye, apparently, is not capable to compensate which thus creates a desire to also introduce a cold color cast in rendered images.

The human eye (actually, not the eye but the brain it connects to) does compensate, even for Arctic light.  Just imagine you are standing around photographing a Polar bear when the temperature is --40...  Of course your brain will see everything as "cold"...

All jokes aside, the compensation actually is there.  It just works a little different.  And specifically a camera does not compensate.  In a typical Arctic location there are fewer dark saturated colors.  Water, tundra, rocks, and snow or ice are very common.  They reflect the skylight better than more saturated colors found in more temperate regions.  So either blue from a cloudless sky or gray clouds with blue filtered light will have more effect than would be so otherwise.  Plus there is "Arctic Haze", or ice crystals in the air that filter light in a way not seen at warmer temperatures.

So the camera will see and record what actually is there.  Lots of pastel skylight with a blue cast to everything.

And humans will see most landscapes as exactly that too. Not much compensation needed because that is what it should look like.  But if we look at something that should be different, such as houses, people, cars... most of them 1) have more saturated colors, and 2) will look "normal" to us even in Arctic light.
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ErikKaffehr
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« Reply #49 on: October 04, 2013, 12:20:23 PM »
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Hi Bart,

I am pretty impressed that we can reconstruct several millions of colors from just three integrated quantities. I think it is quite natural that there is some ambiguity in that interpretation.

Best regards
Erik

Hi Pieter,

I'm a bit puzzled as to why the human eye, apparently, is not capable to compensate which thus creates a desire to also introduce a cold color cast in rendered images.

BTW, I am aware of the existence of blue ice.

Cheers,
Bart
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hjulenissen
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« Reply #50 on: October 04, 2013, 12:25:17 PM »
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I thought that the core problem here was that the illumination is the pastell colored sky (or at least that is the brightest object in the scene, making everything else visible). Only when WB applied as usual, one tries to cancel the "non-whiteness" of that illuminant, thereby removing what is considered a desirable element?

It may well be that the higher-levels of perception in our mind is capable of holding several representations at the same time. Perhaps we can "white-balance" a scene (so as to make "red" objects appear "red") while simultaneously holding an internal reference to the overall/illuminant color temperature for reference?

-h
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JRSmit
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« Reply #51 on: October 04, 2013, 12:40:53 PM »
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So the camera will see and record what actually is there.  Lots of pastel skylight with a blue cast to everything.
I doubt this, it is a limited system with interpretations sort of baked in by the manufacturer.
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« Reply #52 on: October 04, 2013, 01:25:50 PM »
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I doubt this, it is a limited system with interpretations sort of baked in by the manufacturer.

If it were the camera you would see exactly the same thing in pictures from lower latitudes.

Oddly enough, even in BW the difference in Arctic light shows up!  When I first started photographing the Arctic it was using Tri-X 35mm film with a Pentax Spotmatic in the area around the Bering Straits.  It was just wierd!  And what the film showed was almost exactly what it looked like too!  And color slides didn't look much different!  On a normal day in March there is dark water with white ice floating in it, snow covered land, and clouds that reflect either the darkness of the water or the whiteness of the land depending on visual perspective.  No color.
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torger
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« Reply #53 on: October 05, 2013, 06:13:23 AM »
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Could you post a sample image of a scene you think has "realistic" colors? That way we all can be on the same page on what you mean by this term which may not be what we consider as realistic at all.

Thanks for your elaborate reply. I have a few examples earlier in this thread, the post with two pictures attached, one white-balanced for the snow and one fine-tuned after memory (with help of an fellow photographer too), both shot at the same occassion. The point there is that during those arctic light conditions it's not about fine-tuning within a small range, the light is so extreme that it can become hard to find what's right if there's been some time from shooting to processing.

Anyway, I may be mistaken for the typical beginner that thinks what the camera captures is what the eyes see and the rest is just manipulation. However I'm quite aware of the challenges, dynamic range is one of the obvious, ie no matter how hard I stare at my printed sunset I won't get blinded. We need to translate a huge dynamic range into a narrow one, and that means increasing contrast to sacrifice shadows and highlights, and tonemap.

The problem I'm looking at in this thread is hue (and saturation). I experience it difficult in some light conditions to be able to remember and reproduce a hue of the scene that is a realistic representation of the hue as experienced at the scene. Ie, was the colored band in the sky more towards red-pink or blue-magenta, and the color of the snow. Unlike dynamic range I find it less of a need to modify hue to make a good print. I know that you can modify hues and whiten clouds etc to improve the impression of contrast and saturation. I also know about that if you shoot a portrait with someone with a very saturated sweater some light can reflect into the face which you don't think about in reality but causes a tint in the photo, so there are exceptions.

However in the more extreme light conditions I've had in my examples (arctic dusk) it's not about these type of fine-tunings, it's about finding a starting point so you basically know what you're doing. To anyone that has not experienced these type of light conditions I can say it's pretty fantastic, it's so fantastic that I get a desire to be able to show how it really looked in an as realistic way as possible, adapting to the limitations of the medium. Being able to capture and reproduce a reasonably correct hue I think would be a good starting point.
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torger
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« Reply #54 on: October 05, 2013, 06:37:03 AM »
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To elaborate a little bit more with how I look upon "realism"; say if I have a large number of non-photagraphers with me when I make a shot, and then show them the print I made afterwards and ask them if they think it's an honest reproduction of the scene, if they think this is close to "how it actually looked" and most say yes, then I've succeeded.

There is of course no scientific formula of how you should translate an image capture to a print to succeed with this. You'll have to make a number of manipulations to make it look realistic, mainly contrast and tonemapping (which could be just a gradient, I'm not referring to grunge-looking HDR here Smiley ), and there's a lot of personal taste involved on which aspects you think is important to realism or not. For example you may think that a sense of strong contrast is more important than hues, so you whiten your clouds etc to strengthen the sense of contrast. I on the other hand think that hue is a more important aspect and would like to focus on getting those close to the at-scene experience.

What type of modifications you might need to do to the hues due to different viewing conditions I've not gotten into so much yet, but it may not be unlikely that for that arctic light you may need to dampen the blueishness a bit to not make it too unbelievable.

In any case I would appreciate having some sort of tools to be able to have a better baseline on hues when I start to work than exists today.

(I've noted that there seems to be a difference between say american and european audience. The realism/documentary aspect is more popular here in europe, I doubt photographers like Peter Lik or Rodney Lough would be as successful with their printing style on an european market. Adapting a more realistic style does not mean that you totally drop your artistic interpretation and just document, the artistry is in chosen composition, which images you choose to show, and of course you probably still do some dodge and burn and similar to focus your scene in the direction you want and adapt to the printing medium.)
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torger
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« Reply #55 on: October 05, 2013, 06:55:43 AM »
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I thought that the core problem here was that the illumination is the pastell colored sky (or at least that is the brightest object in the scene, making everything else visible). Only when WB applied as usual, one tries to cancel the "non-whiteness" of that illuminant, thereby removing what is considered a desirable element?

It may well be that the higher-levels of perception in our mind is capable of holding several representations at the same time. Perhaps we can "white-balance" a scene (so as to make "red" objects appear "red") while simultaneously holding an internal reference to the overall/illuminant color temperature for reference?

Yes, I can guarantee that on my posted examples that the pastell color is so strong that a normal WB technique will render a much less realistic result than even if you just set the WB to daylight. If someone thinks I'm talking rubbish on that point it's not much more to discuss, then I'd just like to invite them to come and see when winter comes Wink.

My posted examples are relatively "simple", as the light in them is fairly uniform. However, when the sun has not yet set you have both skylight in the shadows and direct sunlight on some parts of the image, those can be extremely difficult to get right. I think what happens there is similar to the effect with multiple artificial light sources, ie the illuminants are so extreme and separated that you can't do with one white balance.

I've attached one such example, I'm actually not entirerly happy with the rendering. More of a snapshot style of image but presented an interesting rendering challenge (both dynamic range and color) so I worked quite long time with it but did not succeed getting to a point which felt 100% right, but it's sort of close I think. Here I've employed a dual white balance, if I only had one white balance and balanced it to get the sun covered mountain yellow-red the snow got greenish, but that is actually more blueish in the shadow. There's also a gradient to fit the bright mountain without darkening the shadowed landscape too much.

I'm suspecting that in this example due to the dynamic range and extreme spectrums there's so much psychovisual things going on that it's pretty impossible to model. If I would try the "manual wb match with live view on site" white balance trick I'd have to make one reference shot for the shadowed landscape and one for the mountain. I hope to make some more photography this winter of this kind as I find this landscape very beautiful and also from a technical perspective very interesting and challenging.

I'm suspecting that someone that has not seen these kind of winter scenes would say "hey, there's a blue cast in your image" and they'd think a white-balanced for the snow would be closer to reality. I've tried that rendering too, but it's so clearly not right for someone that's been on site that I chose this rendering instead, which is the most realistic interpretation of the scene I could make with my current skill and techniques.
« Last Edit: October 05, 2013, 06:59:32 AM by torger » Logged
Czornyj
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« Reply #56 on: October 05, 2013, 07:34:32 AM »
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As an example in a recent discussion about RAW vs jpeg I posted a jpeg rendered by a digital camera:

...then I posted an image that I edited in ACR on my Macbook Retina while watching at the scene (I have perfect score in FM100 hue test, and practiced oil painting while I was a student at Academy of Fine Arts):


Ironically, everyone said that my image doesn't look realistic and that the jpeg has more natural colour rendering Cheesy

Conclusion is that people don't really want realistic colours - which is fine, because cameras are completely unable to render them...
« Last Edit: October 05, 2013, 07:42:42 AM by Czornyj » Logged

Floyd Davidson
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« Reply #57 on: October 05, 2013, 08:07:00 AM »
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Conclusion is that people don't really want realistic colours - which is fine, because cameras are completely unable to render them...

That is a terrific example!  But I would differ slightly with what it demonstrates.  It isn't so much that "people don't want realistic colours", because that is not a picture of the colors!  It's a little bit of what Ansel Adams meant when he said "There is nothing worse than a sharp image of a fuzzy concept."  What Pablo Picasso meant with "Art is the elimination of the unnecessary." and relates to that old saw about shooting in BW makes a photograph of a person's soul while color takes a picture of the color of their clothes.

To be a little more academic about it, Rudolf Arnheim (1904-2007), in "Film as Art" said,

  "This discovery of the gestalt school fitted the notion that the
  work of art, too, is not simply an imitation or selective
  duplication of reality but a translation of observed
  characteristics into the forms of a given medium"

The version that attempts to duplicate the "accurate" colors is wonderful if and only if you have a need to record the colors that existed.  But that isn't the same as making an appealing photograph of the pool, the building, their relationship, or whatever else it might be that is a more useful photograph as a work of art.

If the building's relationship to the pool is the object, then the sky in the first one which is much less of a distraction, is a better choice.  So might be the darker green of the trees in the background.  But the second image makes the building more dominant, though the greens in the foreground could probably be reduced in dominance too.

It's not a matter of what people want, it's a matter of what the photographer wants the image to convey to the viewer!  The image is a photograph (a form of communications, an art form) and is not reality.  Editing needs to consider what is being communicated to the viewer, not what the scene "really" was when you saw it.
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torger
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« Reply #58 on: October 05, 2013, 11:47:41 AM »
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I agree about that you may edit your colors to convey a message, although I think one can do most by saturation and luminance, not hue. I'm also not going to stop shooting long exposures in low light or other cases when the camera can see things impossible with the eye. However, if I could build a post-processing style where I have a firm connection to the eye's experience at the scene, and I would know how much I deviate from that I'd be glad. I want to be subtle, and to be that I need to have some sort of "neutral" starting point which I think sometimes can be hard to find the way I work today.

All too often the feeling that I handle my colors pretty randomly with lots of guessing, and post-processing one day may be different from another day depending on my temper. I guess I'm in the process of trying to find some more structured method to work, and connecting to the color experience at the scene is one of the things.

Sometimes I get the case when I really liked what I saw in terms of color, ie I don't feel that there should be any need to play around with the hues, and try to adjust in post to get the right look as I remembered it, but fail to do so. In that case it would have been nice if there was a way to recreate it (but there isn't...).
« Last Edit: October 05, 2013, 11:56:04 AM by torger » Logged
digitaldog
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« Reply #59 on: October 05, 2013, 01:03:21 PM »
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The version that attempts to duplicate the "accurate" colors is wonderful if and only if you have a need to record the colors that existed.
And where it existed. Color, is a perceptual property. So if you can't see it it's not a color. Color is not a particular wavelength of light. We define colors based on perceptual experiments. Excitation of photoreceptors followed by retinal processing and ending in the visual cortex, this is stuff happening in our head and that's the colors that existed. Cameras operate on a different level with respect to 'color'.
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Andrew Rodney
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