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What an unprocessed photo looks like

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Re: What an unprocessed photo looks like

#101

Post by shagie »

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…

> 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 the luminance (brightness/detail) data.

From the classic file format "ppm" (portable pixel map) the ppm to pgm (portable grayscale map) man page:

https://linux.die.net/man/1/ppmtopgm

    The quantization formula ppmtopgm uses is g = .299 r + .587 g + .114 b.
You'll note the relatively high value of green there, making up nearly 60% of the luminosity of the resulting grayscale image.

I also love the quote in there...

   Quote

   Cold-hearted orb that rules the night
   Removes the colors from our sight
   Red is gray, and yellow white
   But we decide which is right
   And which is a quantization error.
(context for the original - https://www.youtube.com/watch?v=VNC54BKv3mc )

Re: What an unprocessed photo looks like

#102

Post by [deleted] »

disillusioned wrote: post #82
ekidd wrote: post #69

Earlier quoted context omitted.

I have been overusing em dashes and bulleted lists since the actual 80s, I'm sad to say. I spent much of the 90s manually typing "smart" quotes. I have actually been deliberately modifying my long-time writing style and use of punctuation to look less like an LLM. I'm not sure how I feel about this.

Alt + 0151, baby! Or... however you do it on MacOS. But now, likewise, having to bail on emdashes. My last differentiator is that I always close set the emdash—no spaces on either side, whereas ChatGPT typically opens them (AP Style).

[deleted]

Re: What an unprocessed photo looks like

#103

Post by myself248 »

dheera wrote: post #56
krackers wrote: post #4

>if the linear data is displayed directly, it will appear much darker then it should be. This seems more a limitation of monitors. If you had very large bit depth, couldn't you just display images in linear light without gamma correction.

If we're talking about a sunset, then we're talking about your monitor shooting out blinding, eye-hurting brightness light wherever the sun is in the image. That wouldn't be very pleasant.

Which is why I'm looking at replacing my car's rear-view mirror with a camera and a monitor. Because I can hard-cap the monitor brightness and curve the brightness below that, eliminating the problem of billion-lumens headlights behind me.

Re: What an unprocessed photo looks like

#104

Post by make3 »

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.

it's not a crime but applying post processing in an overly generous way that goes a lot further than replicating what a human sees does take away from what makes pictures interesting imho vs other mediums, that it's a genuine representation of something that actually happened.

if you take that away, a picture is not very interesting, it's hyperrealistic so not super creative a lot of the time (compared to eg paintings), & it doesn't even require the mastery of other mediums to get hyperrealistism

Re: What an unprocessed photo looks like

#105

Post by milleramp »

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. (⩺_⩹)

Several reasons, -Silicon efficiency (QE) peaks in the green -Green spectral response curve is close to the luminance curve humans see, like you said. -Twice the pixels to increase the effective resolution in the green/luminance channel, color channels in YUV contribute almost no details.

Why is YUV or other luminance-chrominance color spaces important for a RGB input? Because many processing steps and encoders, work in YUV colorspaces. This wasn't really covered in the article.

Re: What an unprocessed photo looks like

#106

Post by Dylan16807 »

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 can upscale a 170x170 image yourself, if you're not familiar with what that looks like. The only high frequency details you have after upscaling are artifacts. This thing pulled real details out of nowhere.

Re: What an unprocessed photo looks like

#107

Post by numpad0 »

XCSme wrote: post #25
steveBK123 wrote: post #21

Earlier quoted context omitted.

In its most raw form, camera sensors only see illumination not color. In front of the sensor is a bayer filter which results in each physical pixel seeing illumination filtered R G or B. From there the software onboard the camera or in your RAW converter does interpolation to create RGB values at each pixel. For example if the local pixel is R filtered, it then interpolates its G & B values from nearby pixels of that…

What about taking 3 photos while quickly changing the filter (e.g. filters are something like quantum dots that can be turned on/off)?

You can use sets of exotic mirrors and/or prisms to split incoming images into separate RGB beams into three independent monochrome sensors, through the same singular lens and all at once. That's what "3CCD" cameras and their predecessors did.

Re: What an unprocessed photo looks like

#108

Post by mgraczyk »

Dylan16807 wrote: post #106
mgraczyk wrote: post #97

Earlier quoted context omitted.

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 can upscale a 170x170 image yourself, if you're not familiar with what that looks like. The only high frequency details you have after upscaling are artifacts. This thing pulled real details out of nowhere.

That is not true

For example see

https://en.wikipedia.org/wiki/Edge_enhancement

Re: What an unprocessed photo looks like

#109

Post by bloggie »

I work with camera sensors and I think this is a good way to train some of the new guys, with some added segments about the sensor itself and readout. It starts with raw data, something any engineer can understand, and the connection to the familiar output makes for good training.
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