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What an unprocessed photo looks like

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Re: What an unprocessed photo looks like

#141

Post by zinekeller »

shagie wrote: post #139
zinekeller wrote: post #128

Earlier quoted context omitted.

The NTSC color coefficients are the grandfather of all luminance coefficients. It is necessary that it was precisely defined because of the requirements of backwards-compatible color transmission (YIQ is the common abbreviation for the NTSC color space, I being ~reddish and Q being ~blueish), basically they treated B&W (technically monochrome) pictures like how B&W film and videotubes treated them: great in green, av…

To the "the grandfather of all luminance coefficients" ... https://www.earlytelevision.org/pdf/ntsc_signal_specificatio... from 1953. Page 5 has: Eq' = 0.41 (Eb' - Ey') + 0.48 (Er' - Ey') Ei' = -0.27(Eb' - Ey') + 0.74 (Er' - Ey') Ey' = 0.30Er' + 0.59Eg' + 0.11Eb' The last equation are those coefficients.

I was actually researching why PAL YUV has the same(-ish) coefficients, while forgetting that PAL is essentially a refinement of the NTSC color standard (PAL stands for phase-alternating line, which solves much of NTSC's color drift issues early in its life).

Re: What an unprocessed photo looks like

#142

Post by NiloCK »

You may know that intermittent rashes are always invisible in the presence of medical credentials.

Years ago I became suspicious of my Samsung Android device when I couldn't produce a reliable likeness of an allergy induced rash. No matter how I lit things, the photos were always "nicer" than what my eyes recorded live.

The incentives here are clear enough - people will prefer a phone whose camera gives them an impression of better skin, especially when the applied differences are extremely subtle and don't scream airbrush. If brand-x were the only one to allow "real skin" into the gallery viewer, people and photos would soon be decried as showing 'x-skin', which would be considered gross. Heaven help you if you ever managed to get close to a mirror or another human.

To this day I do not know whether it was my imagination or whether some inline processing effectively does or did perform micro airbrushing on things like this.

Whatever did or does happen, the incentive is evergreen - media capture must flatter the expectations of its authors, without getting caught in its sycophancy. All the while, capacity improves steadily.

Re: What an unprocessed photo looks like

#143

Post by jsrcout »

Waterluvian wrote: post #45

I studied remote sensing in undergrad and it really helped me grok sensors and signal processing. My favourite mental model revelation to come from it was that what I see isn’t the “ground truth.” It’s a view of a subset of the data. My eyes, my cat’s eyes, my cameras all collect and render different subsets of the data, providing different views of the subject matter. It gets even wilder when perceiving space and ti…

And not only that, our sensors can return spurious data, or even purposely constructed fake data, created with good or evil intent.

I've had this in mind at times in recent years due to $DAYJOB. We use simulation heavily to provide fake CPUs, hardware devices, what have you, with the goal of keeping our target software happy by convincing it that it's running in its native environment instead of on a developer laptop.

Just keep in mind that it's important not to go _too_ far down the rabbit hole, one can spend way too much time in "what if we're all just brains in jars?"-land.

Re: What an unprocessed photo looks like

#144

Post by AlotOfReading »

jiggawatts wrote: post #80

I've been studying machine learning during the xmas break, and as an exercise I started tinkering around with the raw Bayer data from my Nikon camera, throwing it at various architectures to see what I can squeeze out of the sensor. Something that surprised me is that very little of the computation photography magic that has been developed for mobile phones has been applied to larger DSLRs. Perhaps it's because it's…

This stuff exists and it's fairly well-studied. It's surprisingly hard to find without coming across it in literature though, the universe of image processing is huge. Joint demosaicing, for example, is a decades-old technique [0] fairly common in astrophotography. Commercial photographers simply never cared or asked for it, and so the tools intended for them didn't bother either. You'd find more of it in things like scientific ISP and robotics.

[0] https://doi.org/10.1145/2980179.2982399

Re: What an unprocessed photo looks like

#145

Post by ycombiredd »

zinekeller wrote: post #128
ycombiredd wrote: post #111

Earlier quoted context omitted.

Interesting that the "NTSC" look you describe is essentially rounded versions of the coefficients quoted in the comment mentioning ppm2pgm. I don't know the lineage of the values you used of course, but I found it interesting nonetheless. I imagine we'll never know, but it would be cool to be able to trace the path that lead to their formula, as well as the path to you arriving at yours

The NTSC color coefficients are the grandfather of all luminance coefficients. It is necessary that it was precisely defined because of the requirements of backwards-compatible color transmission (YIQ is the common abbreviation for the NTSC color space, I being ~reddish and Q being ~blueish), basically they treated B&W (technically monochrome) pictures like how B&W film and videotubes treated them: great in green, av…

Cool. I could have been clearer in my post; as I understand it actual NTSC circuitry used different coefficients for RGBx and RGBy values, and I didn't take time to look up the official standard. My specific pondering was based on an assumption that neither the ppm2pgm formula nor the parent's "NTSC" formula were exact equivalents to NTSC, and my "ADHD" thoughts wondered about the provenance of how each poster came to use their respective approximations. While I write this, I realize that my actual ponderings are less interesting than the responses generated because of them, so thanks everyone for your insightful responses.

Re: What an unprocessed photo looks like

#146

Post by userbinator »

mgraczyk wrote: post #97
userbinator wrote: post #93

Earlier quoted context omitted.

If you read the original source article, you'll find this important line: I downsized it to 170x170 pixels

And? What algorithm was used for downsampling? What was the high frequency content of the downsampled imagine after doing a psuedo inverse with upsampling? How closely does it match the Samsung output? My point is that there IS an experiment which would show that Samsung is doing some nonstandard processing likely involving replacement. The evidence provided is insufficient to show that

You have clearly made no attempts to read the original article which has a lot more evidence (or are actively avoiding it), and somehow seem to be defending Samsung voraciously but emptily, so you're not worth arguing with and I'll just leave this here:

I zoomed in on the monitor showing that image and, guess what, again you see slapped on detail, even in the parts I explicitly clipped (made completely 100% white):

Re: What an unprocessed photo looks like

#147

Post by nerdponx »

NiloCK wrote: post #142

You may know that intermittent rashes are always invisible in the presence of medical credentials. Years ago I became suspicious of my Samsung Android device when I couldn't produce a reliable likeness of an allergy induced rash. No matter how I lit things, the photos were always "nicer" than what my eyes recorded live. The incentives here are clear enough - people will prefer a phone whose camera gives them an impre…

I've had problems like this before, but I always attributed it to auto white balance. That great ruiner of sunset photos the world over.

Re: What an unprocessed photo looks like

#148

Post by Eisenstein »

BenjiWiebe wrote: post #134
Eisenstein wrote: post #115

Earlier quoted context omitted.

Do you also want the IR light to be in there? That would make it more of 'genuine representation'.

Wouldn't be a genuine version of what my eyes would've seen, had I been the one looking instead of the camera. I can't see infrared.

But the camera is trying to emulate how it would look if your eyes were seeing it. In order for it to be 'genuine' you would need not only the camera to genuine, but also the OS, the video driver, the viewing app, the display and the image format/compression. They all do things to the image that are not genuine.

Re: What an unprocessed photo looks like

#150

Post by fc417fc802 »

dheera wrote: post #39
barishnamazov wrote: post #7

I love posts that peel back the abstraction layer of "images." It really highlights that modern photography is just signal processing with better marketing. A fun tangent on the "green cast" mentioned in the post: the reason the Bayer pattern is RGGB (50% green) isn't just about color balance, but spatial resolution. The human eye is most sensitive to green light, so that channel effectively carries the majority of t…

This is also why I absolute hate, hate, hate it when people ask me whether I "edited" a photo or whether a photo is "original", as if trying to explain away nice-looking images as if they are fake. The JPEGs cameras produce are heavily processed, and they are emphatically NOT "original". Taking manual control of that process to produce an alternative JPEG with different curves, mappings, calibrations, is not a crime.

There's a difference between an unbiased (roughly speaking) pipeline and what (for example) JBIG2 did. The latter counts as "editing" and "fake" as far as I'm concerned. It may not be a crime but at least personally I think it's inherently dishonest to attempt to play such things off as "original".

And then there's all the nonsense BigTech enables out of the box today with automated AI touch ups. That definitely qualifies as fakery although the end result may be visually pleasing and some people might find it desirable.

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