That’s why I use cameras, so I can see things differently.
Or show other people how I see things.
Welcome back, @zaknu
While that is a noble goal, it is also somehow futile.
Because you as a human will see the original scene differently every time.
If you go for “scientific” what is your reference point?
I always photograph with a single fixed white-balance settings in the camera.
This allows me to see color casts already in the preview.
Do I use that fixed WB later on? Yeah, most of the time.
I’ll just go with it because it gives the viewer a reference point, a hint of mood.
A lot of stuff I do is documentary, reportage style, so it fits and works rather well.
But some scenes I’ll will change the WB, because it just looks bad.
A classic would be photos taken under trees.
People and green light are just aweful, even if it would be “correct”.
Compared to how much invention/guesswork your brain does when it constructs an image in your mind, most “normal” photo editing tools do nothing. Honestly even AI-invented data wouldn’t be much of a step beyond how your mind constructs information in your peripheral vision.
I see a lot of people posting things like “I want colours as I remember them” on here. There’s no way you remember colours as they were, and it’s extremely unlikely you even saw the colours as they were. Even the “data” that the camera collects is skewed by the equipment used to collect it and the processes used to turn the raw (monochrome) data into colour.
Reality is an invention.
Well, colorimeters exist, and they give what is generally accepted as the real colour of a surface.
That said, those instruments use rigorously defined light sources and calibration standards…
So at least in theory you should be able to get those colours. But that won’t take int account surface texture (which can add white to the colour), illuminant colours etc. So while your colours might be scientifically correct, the image probably isn’t.
of course, an extreme way would be to capture a spectrum for each pixel, and reproduce that (as much as possible with the three colours available in most colour spaces…).
But much more important: would such a “correct” image be pleasing to the spectator?
Case in point:
But context plays a role too: a bit of leftover green will be much more objectionable if you cannot see the cause of the green tint… Or you might get the feeling that something is “off”, when you see the trees, without the cast on the objects beneath it.
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Yeah that last line was a bit tongue-in-cheek. I’m a physicist by education so I agree reality does exist. It’s just not well represented inside your brain.
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After more than twenty years of professional work and training in that realm I have to disagree slightly but agree in general. It is very hard. Still. Experience helps a lot, because you have literally seen and done it so many times that you know what is there. You know how certain things react to certain light.
For example ever noticed the greenish-yellow light on the fruits & vegetables and the red light on the meat sections in the super market? That’s by design. Also those sections are designed in a way that your reference is killed. It only takes a slight hint of green/cyan in the “white” objects to counter the red light and boom! meat looks great.
Human vision is built around change and not on absolutes.
We do so much better with contrast and lights and shadows than we do with color.
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Again people are back to arguing at the wrong level imho. Of course there are memory colours and a huge host of other perception ‘malfunctions’ It doesn’t matter.
Following the example from @flannelhead link
Consider text. You can write about an event or describe a scene without adding fake information. Despite text being a medium completely divorced from the scene and there’s not really any way to scientifically map between the two. You can write ‘It was Monday’ and it would be true. But Monday doesn’t ‘exist’ it also gives an extremely limited description. You could then add ‘it was raining’ still true and fidelity was increased. However in Spain it wasn’t raining does that make it false? You have scope and context and limitations all the time for everything.
- Iso 3200 half frame bw photo = It is Monday = true
Of course with photography you have lots and lots of support rails to prevent you from going completely off. Rails lacking when writing. Generally speaking any sooc photo will be pretty good.
It’s really funny to see how people take the lack of absolute truth as an argument for free for all floating nothingless everything goes. Even scientists should understand that their theories, measurements, concepts and language are never the real thing and at best constantly improving approximations. Those certain for instance that math is “real” havent really considered the issue or what real might mean in this context. To be disconcerted by this is silly.
Photography is a social thing, at it’s best art. As in science the bondaries for accurate or “truth” are context dependent, constantly negotiated and developed.
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Traditional ‘fine art’, in earlier times, always tried to emulate some personal idea of reality. Photography follows in that footprint.
Painters moved from that mold and the photographer should be emboldened to follow suit rather than argue over the whiteness of white.
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Which photographer? Certainly some genres of photography rely on exact reproduction (medical imaging), some on completely false imaging (deep space photography), some on minimal editing (photojournalism) and some are artistically free to do what they please.
As for colour reproduction - camera profiles need broad spectrum high CRI/TLCI lighting, and you need an accurate set of values for whichever chart you use, or you can calibrate each shoot for the lights present (Although it’s a bit moot with a format that applies gamma on R, G and B like sRGB as that adds a hue and saturation shift)
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Visual reproduction, rather than magnetic, sound waves or x-ray based.
Described in ISO TC42’s work on new image formats. https://www.color.org/hdr/07-Nicolas_Bonnier.pdf
Medical imaging that requires accuracy would include Dual-energy X-ray absorptiometry - Wikipedia and Quantitative computed tomography - Wikipedia to calculate bone mineral density.
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I would say that it is the correspondence of some aspect of tone or color to positive indication of some anomaly. Low false-positive, false-negative assertions…
I suppose you mean “a picture using X-rays”.
DEXA scans seem to have precision and accuracy of about 1 part in 10,000.
EDIT: Sorry, I mean the precision and consistency is about 1:10,000. I can’t easily find information on accuracy.
… we can’t see an X-ray?
True, but that is about perception of the human visual system. We can’t see X-rays. We can’t normally see ultra-violet (but I expect to be able to see them briefly this week.) The OP question was about not adding fake information to the original signal. DEXA “cameras” have signals, and take great care not to add fake information.
By the way, X-rays are nor longer done on film but with digital acquisition. The images are post processed to enhance image contrast, reduce image noise and increase the sharpness.
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An X-ray is taken to determine various conditions in the body. To effectively do that, the conditions of interest have to discern themselves in some way to the medical practitioner; in the case of monochrome x-ray renditions, by contrast. I’ve watched this time and again with my dentist, who’ll take x-rays of my mouth and discuss nascent decay in terms of its contrast to the healthy tooth material…
“Accuracy” in an x-ray rendition is about its ability to discern specific conditions in the body, with as few false calls as possible.
Even my skin doctor made a photo of my skin and the colours were totally off by design.
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Even black and white film doesn’t reproduce reality - there is a deliberate twist to the chemistry to enhance edges of contrast. It works basically the same way as a sharpening algorithm, brighten up the bright edge and darken the dark edge.
And then there is the retina with its neural networks, transforming the output of the cones and rods into patterns of nerve signals, that represent edges, contrasts, gradients, … and a little bit of colour information. In the brain these signals are thrown into a cascade of neural networks and at the end there is a crude neural representation of the world which is filled up by a lot of memory and assumptions. Our brain constructs the world around us.
The next question would be who looks at that image and we are off at the deep end. (I read Neuro at a professor who had a doctorate in philosophy and biology, my mind was blown.)
The reproduction of the visual experience in moment of capturing the image is only possible if you remember the moment. And for remembering the moment you don’t need a technically perfect image - even a sea shell or the smell of a madeleine can evoke a vivid memory.
(And memory is newly reconstructed every time you think about something, worse data retention than cassette tapes for a C64. That make an eye witness less reliable after every round of questioning.)
Outside of technical documentation there are only one questions for me - can the final image evoke a certain emotion in me? And if, have I captured enough building blocks that the image can evoke a similar emotion in others?
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I would asset that x-ray technicians are photographers who can evoke the widest range of emotions…
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For DEXA, intensities of a pair of images are used to calculate the areal density of bone. If we drilled out a cylinder of the bone with cross-section one square centimetre, that would be its weight in grams. (The approximate answer is: one gram.) Accurate diagnosis, and treatment evaluation, etc, depend on accurate density measurements, which in turn depend on accurate image intensities.
Some information about how the “camera” and “photographer” work to achieve the accuracy is in, for example, https://wwwn.cdc.gov/nchs/data/nhanes3/manuals/bone.pdf (1989). We might smile at the use of floppy disks and a computer with a whopping 20 MB hard drive.