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What an unprocessed photo looks like

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Re: What an unprocessed photo looks like

#241

Post by Toutouxc »

card_zero wrote: post #228
Toutouxc wrote: post #227

Earlier quoted context omitted.

In that case you can't reasonably do digital photography without "fake cosmetic bullshit" and no current digital camera will output anything even remotely close to no fake cosmetic bullshit.

That sounds likely. I wonder what specific filters can't be turned off, though. I think you can usually turn off sharpening. Maybe noise removal is built-in somehow (I think somebody else said it's in the sensor).

I think you’ll find that there is no clear line between what you call fake bullshit and the rest of the process. The entire signal path is optimized at every step to reduce and suppress noise. There’s actual light noise, there’s readout noise, ADC noise, often dozens or hundreds of abnormal pixels. Certain autofocus technologies even sacrifice image-producing pixels, and simply interpolate over the “holes” in data.

Regarding sharpening and optical stuff, many modern camera lenses are built with the expectation that some of their optical properties will be easy to correct for in software, allowing the manufacturer to optimize for other properties.

Re: What an unprocessed photo looks like

#243

Post by fleabitdev »

mwambua wrote: post #182
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…

> The human eye is most sensitive to green light, so that channel effectively carries the majority of the luminance (brightness/detail) data How does this affect luminance perception for deuteranopes? (Since their color blindness is caused by a deficiency of the cones that detect green wavelengths)

Protanopia and protanomaly shift luminance perception away from the longest wavelengths of visible light, which causes highly-saturated red colours to appear dark or black. Deuteranopia and deuteranomaly don't have this effect. [1]

Blue cones make little or no contribution to luminance. Red cones are sensitive across the full spectrum of visual light, but green cones have no sensitivity to the longest wavelengths [2]. Since protans don't have the "hardware" to sense long wavelengths, it's inevitable that they'd have unusual luminance perception.

I'm not sure why deutans have such a normal luminous efficiency curve (and I can't find anything in a quick literature search), but it must involve the blue cones, because there's no way to produce that curve from the red-cone response alone.

[1]: https://en.wikipedia.org/wiki/Luminous_efficiency_function#C...

[2]: https://commons.wikimedia.org/wiki/File:Cone-fundamentals-wi...

Re: What an unprocessed photo looks like

#245

Post by mradalbert »

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…

Also worth noting that manufacturers advertise photodiode count as a sensor resolution. So if you have 12 Mp sensor then your green resolution is 6 Mp and blue and red are 3 Mp

Re: What an unprocessed photo looks like

#246

Post by fleabitdev »

doubletwoyou wrote: post #203
mwambua wrote: post #182

Earlier quoted context omitted.

> The human eye is most sensitive to green light, so that channel effectively carries the majority of the luminance (brightness/detail) data How does this affect luminance perception for deuteranopes? (Since their color blindness is caused by a deficiency of the cones that detect green wavelengths)

The cones are the colour sensitive portion of the retina, but only make up a small percent of all the light detecting cells. The rods (more or less the brightness detecting cells) would still function in a deuteranopic person, so their luminance perception would basically be unaffected. Also there’s something to be said about the fact that the eye is a squishy analog device, and so even if the medium wavelengths cone…

The rods are only active in low-light conditions; they're fully active under the moon and stars, or partially active under a dim street light. Under normal lighting conditions, every rod is fully saturated, so they make no contribution to vision. (Some recent papers have pushed back against this orthodox model of rods and cones, but it's good enough for practical use.)

This assumption that rods are "the luminance cells" is an easy mistake to make. It's particularly annoying that the rods have a sensitivity peak between the blue and green cones [1], so it feels like they should contribute to colour perception, but they just don't.

[1]: https://en.wikipedia.org/wiki/Rod_cell#/media/File:Cone-abso...

Re: What an unprocessed photo looks like

#247

Post by shiandow »

jamilton wrote: post #168
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…

Why that ratio in particular? I wonder if there’s a more complex ratio that could be better.

This ratio allows for a relatively simple 2x2 repeating pattern. That makes interpolating the values immensely simpler.

Also you don't want the red and blue to be too far apart, reconstructing the colour signal is difficult enough as it is. Moire effects are only going to get worse if you use an even sparser resolution.

Re: What an unprocessed photo looks like

#248

Post by shiandow »

thousand_nights wrote: post #63
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…

the bayer pattern is one of those things that makes me irrationally angry, in the true sense, based on my ignorance of the subject what's so special about green? oh so just because our eyes are more sensitive to green we should dedicate double the area to green in camera sensors? i mean, probably yes. but still. (⩺_⩹)

You think that's bad? Imagine finding out that all video still encodes colour at half resolution simply because that is how analog tv worked.

Re: What an unprocessed photo looks like

#249

Post by pbalau »

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…

> 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 not as desperately needed, or because prior to the current AI madness nobody had sufficient GPU power lying around for such a purpose.

Sony Alpha 6000 had face detection in 2014.

Re: What an unprocessed photo looks like

#250

Post by cataflam »

integralid wrote: post #201
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…

And this is just what happens for a single frame. It doesn't even touch computational photography[1]. [1] https://dpreview.com/articles/9828658229/computational-photo...

Great series of articles!
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