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The bit about the green over-representation in camera color filters is partially correct. Human color sensitivity varies a lot from individual to individual (an

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 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.

NooneAtAll3 10mo ago
> we are most sensitive to red light > green does indeed overwhelmingly contribute to perceptual luminance so... if luminance contribution is different from "sensitivity" to you - what do you imply by sensitivity?
- liampulles 10mo ago
  Upon further reading, I think I am wrong here. My confusion was that I read that over 60% of the cones in ones eye are "red" cones (which is a bad generalization), and there is more nuance here. Given equal power red, blue, or green light hitting our eyes, humans tend to rate green "brighter" in pairwise comparative surveys. That is why it is predominant in a perceptual luminance calculation converting from RGB. Though there are much more L-cones (which react most strongly to "yellow" light, not "red", also "much more" varies across individuals) than M-cones (which react most strongly to a "greenish cyan"), the combination of these two cones (which make ~95% of the cones in the eye) mean that we are able to sense green light much more efficiently than other wavelengths. S-cones (which react most strongly to "purple") are very sparse.
  - skinwill 9mo ago
    This is way over simplifying here but I always understood it as: our eyes can see red with very little power needed. But our eyes can differentiate more detail with green.
devsda 10mo ago
Is it related to the fact that monkeys/humans evolved around dense green forests ?
- frumiousirc 9mo ago
  Well, plants and eyes long predate apes. Water is most transparent in the middle of the "visible" spectrum (green). It absorbs red and scatters blue. The atmosphere has a lot of water as does, of course, the ocean which was the birth place of plants and eyeballs. It would be natural for both plants and eyes to evolve to exploit the fact that there is a green notch in the water transparency curve. Edit: after scrolling, I find more discussion on this below.
  - seba_dos1 9mo ago
    Eyes aren't all equal. Our trichromacy is fairly rare in the world of animals.
- zuminator 9mo ago
  I think any explanation along those lines would have a "just-so" aspect to it. How would we go about verifying such a thing? Perhaps if we compared and contrasted the eyes of savanna apes to forest apes, and saw a difference, which to my knowledge We do not. Anyway, sunlight at the ground level peaks around 555nm, so it's believed that we're optimizing to that by being more sensitive to green.
kuschku 9mo ago
> 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. Considering you usually shoot RAW, and debayer and process in post, the camera hasn't done any of that. It's only smartphones that might be doing internal AI Debayering, but they're already hallucinating most of the image anyway.
- 15155 9mo ago
  Yes, people usually shoot RAW (anyone spending this much on a camera knows better) - but these cameras default to JPEG and often have dual-capture (RAW+JPEG) modes.
  - qubitcoder 9mo ago
    To be clear, they default to JPEG for the image preview on the monitor (LCD screen). Whenever viewing an image on a professional camera, you’re always seeing the resulting JPEG image. The underlying data is always captured as a RAW file, and only discarded if you’ve configured the camera to only store the JPEG image (discarding the original RAW file after processing).
    - 15155 9mo ago
      > Whenever viewing an image on a professional camera Viewing any preview image on any camera implies a debayered version: who says is it JPEG-encoded - why would it need to be? Every time I browse my SD card full of persisted RAWs, is the camera unnecessarily converting to JPEG just to convert it back to bitmap display data? > The underlying data is always captured as a RAW file, and only discarded if you’ve configured the camera to only store the JPEG image (discarding the original RAW file after processing). Retaining only JPEG is the default configuration on all current-generation Sony and Canon mirrorless cameras: you have to go out of your way to persist RAW.
      - account42 9mo ago

NooneAtAll3 10mo ago

> we are most sensitive to red light > green does indeed overwhelmingly contribute to perceptual luminance so... if luminance contribution is different from "sensitivity" to you - what do you imply by sensitivity?

liampulles 10mo ago
Upon further reading, I think I am wrong here. My confusion was that I read that over 60% of the cones in ones eye are "red" cones (which is a bad generalization), and there is more nuance here. Given equal power red, blue, or green light hitting our eyes, humans tend to rate green "brighter" in pairwise comparative surveys. That is why it is predominant in a perceptual luminance calculation converting from RGB. Though there are much more L-cones (which react most strongly to "yellow" light, not "red", also "much more" varies across individuals) than M-cones (which react most strongly to a "greenish cyan"), the combination of these two cones (which make ~95% of the cones in the eye) mean that we are able to sense green light much more efficiently than other wavelengths. S-cones (which react most strongly to "purple") are very sparse.
- skinwill 9mo ago
  This is way over simplifying here but I always understood it as: our eyes can see red with very little power needed. But our eyes can differentiate more detail with green.

devsda 10mo ago

Is it related to the fact that monkeys/humans evolved around dense green forests ?

frumiousirc 9mo ago
Well, plants and eyes long predate apes. Water is most transparent in the middle of the "visible" spectrum (green). It absorbs red and scatters blue. The atmosphere has a lot of water as does, of course, the ocean which was the birth place of plants and eyeballs. It would be natural for both plants and eyes to evolve to exploit the fact that there is a green notch in the water transparency curve. Edit: after scrolling, I find more discussion on this below.
- seba_dos1 9mo ago
  Eyes aren't all equal. Our trichromacy is fairly rare in the world of animals.
zuminator 9mo ago
I think any explanation along those lines would have a "just-so" aspect to it. How would we go about verifying such a thing? Perhaps if we compared and contrasted the eyes of savanna apes to forest apes, and saw a difference, which to my knowledge We do not. Anyway, sunlight at the ground level peaks around 555nm, so it's believed that we're optimizing to that by being more sensitive to green.

kuschku 9mo ago

> 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. Considering you usually shoot RAW, and debayer and process in post, the camera hasn't done any of that. It's only smartphones that might be doing internal AI Debayering, but they're already hallucinating most of the image anyway.

15155 9mo ago
Yes, people usually shoot RAW (anyone spending this much on a camera knows better) - but these cameras default to JPEG and often have dual-capture (RAW+JPEG) modes.
- qubitcoder 9mo ago
  To be clear, they default to JPEG for the image preview on the monitor (LCD screen). Whenever viewing an image on a professional camera, you’re always seeing the resulting JPEG image. The underlying data is always captured as a RAW file, and only discarded if you’ve configured the camera to only store the JPEG image (discarding the original RAW file after processing).
  - 15155 9mo ago
    > Whenever viewing an image on a professional camera Viewing any preview image on any camera implies a debayered version: who says is it JPEG-encoded - why would it need to be? Every time I browse my SD card full of persisted RAWs, is the camera unnecessarily converting to JPEG just to convert it back to bitmap display data? > The underlying data is always captured as a RAW file, and only discarded if you’ve configured the camera to only store the JPEG image (discarding the original RAW file after processing). Retaining only JPEG is the default configuration on all current-generation Sony and Canon mirrorless cameras: you have to go out of your way to persist RAW.
    - account42 9mo ago