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What an unprocessed photo looks like

maurycyz.com

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Re: What an unprocessed photo looks like

#71

Post by Sharlin »

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.

No. It's about the shape of the curve. Human light intensity perception is not linear. You have to nonlinearize at some point of the pipeline, but yes, typically you should use high-resolution (>=16 bits per channel) linear color in calculations and apply the gamma curve just before display. The fact that traditionally this was not done, and linear operations like blending were applied to nonlinear RGB values, resulted in ugly dark, muddy bands of intermediate colors even in high-end applications like Photoshop.

Re: What an unprocessed photo looks like

#72

Post by dheera »

zmgsabst wrote: post #66
dheera wrote: post #44

Earlier quoted context omitted.

Photography is also an art. When painters jack up saturations in their choices of paint colors people don't bat an eyelid. There's no good reason photographers cannot take that liberty as well, and tone mapping choices is in fact a big part of photographers' expressive medium. If you want reality, go there in person and stop looking at photos. Viewing imagery is a fundamentally different type of experience.

Sure — but people reasonably distinguish between photos and digital art, with “photo” used to denote the intent to accurately convey rather than artistic expression. We’ve had similar debates about art using miniatures and lens distortions versus photos since photography was invented — and digital editing fell on the lens trick and miniature side of the issue.

Journalistic/event photography is about accuracy to reality, almost all other types of photography are not.

Portrait photography -- no, people don't look like that in real life with skin flaws edited out

Landscape photography -- no, the landscapes don't look like that 99% of the time, the photographer picks the 1% of the time when it looks surreal

Staged photography -- no, it didn't really happen

Street photography -- a lot of it is staged spontaneously

Product photography -- no, they don't look like that in normal lighting

Re: What an unprocessed photo looks like

#73

Post by ChrisMarshallNY »

That's a cool walkthrough.

I spent a good part of my career, working in image processing.

That first image is pretty much exactly what a raw Bayer format looks like, without any color information. I find it gets even more interesting, if we add the RGB colors, and use non-square pixels.

Re: What an unprocessed photo looks like

#74

Post by kccqzy »

barishnamazov wrote: post #36
delecti wrote: post #23

Earlier quoted context omitted.

I have a related anecdote. When I worked at Amazon on the Kindle Special Offers team (ads on your eink Kindle while it was sleeping), the first implementation of auto-generated ads was by someone who didn't know that properly converting RGB to grayscale was a smidge more complicated than just averaging the RGB channels. So for ~6 months in 2015ish, you may have seen a bunch of ads that looked pretty rough. I think I…

I don't think Kindle ads were available in my region in 2015 because I don't remember seeing these back then, but you're a lucky one to fix this classic mistake :-) I remember trying out some of the home-made methods while I was implementing a creative work section for a school assignment. It’s surprising how "flat" the basic average looks until you actually respect the coefficients (usually some flavor of 0.21R + 0.…

I remember using some photo editing software (Aperture I think) that would allow you to customize the different coefficients and there were even presets that give different names to different coefficients. Ultimately you can pick any coefficients you want, and only your eyes can judge how nice they are.

Re: What an unprocessed photo looks like

#77

Post by seba_dos1 »

to11mtm wrote: post #58
dheera wrote: post #39

Earlier quoted context omitted.

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.

JPEG with OOC processing is different from JPEG OOPC (out-of-phone-camera) processing. Thank Samsung for forcing the need to differentiate.

I wrote the raw Bayer to JPEG pipeline used by the phone I write this comment on. The choices on how to interpret the data are mine. Can I tweak these afterwards? :)

Re: What an unprocessed photo looks like

#78

Post by lidavidm »

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)?

Olympus and other cameras can do this with "pixel shift": it uses the stabilization mechanism to quickly move the sensor by 1 pixel.

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

EDIT: Sigma also has "Foveon" sensors that do not have the filter and instead stacks multiple sensors (for different wavelengths) at each pixel.

https://en.wikipedia.org/wiki/Foveon_X3_sensor

Re: What an unprocessed photo looks like

#79

Post by card_zero »

nomel wrote: post #67
card_zero wrote: post #29

Earlier quoted context omitted.

In the example ("let's color each pixel ...") the layout is: R G G B Then at a later stage the image is green because "There are twice as many green pixels in the filter matrix".

And this is important because our perception is more sensitive to luminance changes than color, and with our eyes being most sensitive to green, luminance is also. So, higher perceived spatial resolution by using more green [1]. This is also why JPG has lower resolution red and green channels, and why modern OLED usually use a pentile display, with only green being at full resolutio [2]. [1] https://en.wikipedia.org/…

Funny that subpixels and camera sensors aren't using the same layouts.

Re: What an unprocessed photo looks like

#80

Post by jiggawatts »

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

For example, it's a relatively straightforward exercise to feed in "dark" and "flat" frames as extra per-pixel embeddings, which lets the model learn about the specifics of each individual sensor and its associated amplifier. In principle, this could allow not only better denoising, but also stretch the dynamic range a tiny bit by leveraging the less sensitive photosites in highlights and the more senstive ones in the dark areas.

Similarly, few if any photo editing products do simultaneous debayering and denoising, most do the latter as a step in normal RGB space.

Not to mention multi-frame stacking that compensates for camera motion, etc...

The whole area is "untapped" for full-frame cameras, someone just needs to throw a few server grade GPUs at the problem for a while!

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