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What an unprocessed photo looks like

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Re: What an unprocessed photo looks like

#211

Post by raphman »

JumpCrisscross wrote: post #181
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…

> modern photography is just signal processing with better marketing I pass on a gift I learned of from HN : Susan Sunday’s “On Photography”.

Thanks! First hit online: https://www.lab404.com/3741/readings/sontag.pdf

Out of curiosity: what led you to write "Susan Sunday" instead of "Susan Sontag"? (for other readers: "Sonntag" is German for "Sunday")

Re: What an unprocessed photo looks like

#212

Post by akx »

shagie wrote: post #101
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://li…

If someone's curious about those particular constants, they're the PAL Y' matrix coefficients: https://en.wikipedia.org/wiki/Y%E2%80%B2UV#SDTV_with_BT.470

Re: What an unprocessed photo looks like

#213

Post by gudzpoz »

f1shy wrote: post #202
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, This argument is very confusing: if is most sensitive, less intensity/area should be necessary, not more.

Note that there are two measurement systems involved: first the camera, and then the human eyes. Your reasoning could be correct if there were only one: "the sensor is most sensitive to green light, so less sensor area is needed".

But it is not the case, we are first measuring with cameras, and then presenting the image to human eyes. Being more sensitive to a colour means that the same measurement error will lead to more observable artifacts. So to maximize visual authenticity, the best we can do is to make our cameras as sensitive to green light (relatively) as human eyes.

Re: What an unprocessed photo looks like

#214

Post by Lvl999Noob »

f1shy wrote: post #202
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, This argument is very confusing: if is most sensitive, less intensity/area should be necessary, not more.

Since the human eye is most sensitive to green, it will find errors in the green channel much easier than the others. This is why you need _more_ green data.

Re: What an unprocessed photo looks like

#215

Post by Maxion »

astrange wrote: post #191
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…

iOS added a camera mode for medical photos that extra doesn't do that. https://developer.apple.com/videos/play/wwdc2024/10162/

Huh wonder which camera apps enable use of this API?

Re: What an unprocessed photo looks like

#216

Post by liampulles »

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 bit about the green over-representation in camera color filters is partially correct. Human color sensitivity varies a lot from individual to individual (and not just amongst individuals with color blindness), but general statistics indicate we are most sensitive to red light.

The main reason is that green does indeed overwhelmingly contribute to perceptual luminance (over 70% in sRGB once gamma corrected: https://www.w3.org/TR/WCAG20/#relativeluminancedef) and modern demosaicking algorithms will rely on both derived luminance and chroma information to get a good result (and increasingly spatial information, e.g. "is this region of the image a vertical edge").

Small neural networks I believe are the current state of the art (e.g. train to reverse a 16x16 color filter pattern for the given camera). What is currently in use by modern digital cameras is all trade secret stuff.

Re: What an unprocessed photo looks like

#217

Post by Dylan16807 »

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.

Linear encoding doesn't change the max brightness of the monitor.

More importantly, the camera isn't recording blinding brightness in the first place! It'll say those pixels are pure white, which is probably a few hundred or thousand nits depending on shutter settings.

Re: What an unprocessed photo looks like

#218

Post by qingcharles »

brookst wrote: post #100
sho_hn wrote: post #54

Earlier quoted context omitted.

Upon inspection, the author's personal website used em dashes in 2023. I hope this helped with your witch hunt. I'm imagining a sort of Logan's Run-like scifi setup where only people with a documented em dash before November 30, 2022, i.e. D(ash)-day, are left with permission to write.

Phew. I have published work with em dashes, bulleted lists, “not just X, but Y” phrasing, and the use of “certainly”, all from the 90’s. Feel sorry for the kids, but I got mine.

I'm grandfathered in too. RIP the hyphen crew.

Re: What an unprocessed photo looks like

#220

Post by qingcharles »

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).

I'm a savage, I just copy-paste them from Unicode sites.
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