Good read. Funny how I always thought the sensor read rgb, instead of simple light levels in a filter pattern.
this post was submitted on 29 Dec 2025
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wild how far technology has marched on and yet we're still essentially using the same basic idea behind technicolor. but hey, if it works!
For a while the best/fanciest digital cameras had three CCDs, one for each RGB color channel. I'm not sure if that's still the case or if the color filter process is now good enough to replace it.
You could see the little 2x2 blocks as a pixel and call it RGGB. It's done like this because our eyes are so much more sensitive to the middle wavelengths, our red and blue cones can detect some green too. So those details are much more important.
A similar thing is done in jpeg, the green channel always has the most information.
This is why I don’t say I need to edit my photos, but instead I need to process them. Editing is clearly understood by the layperson as Photoshop and while they don’t understand processing necessarily, many people still understand taking photos to a store and getting them processed from the film to a photo they can give someone.
How do you get a sensor data image from a camera?
Most cameras will let you export raw files, and a lot of phones do as well(although the phone ones aren't great since they usually do a lot of processing on it before giving you the normal picture)
RAW files. Even then, you mostly see the processed result based on whatever processing your raw image viewer/editor does. But if you know how to get to it and use it, the same raw sensor capture data is there
I'm a little confused on how the demosaicing step produced a green-tinted photo. I understand that there are 2x green pixels, but does the naive demosaic process just show the averaged sensor data which would intrinsically have "too much" green, or was there an error with the demosaicing?
Yes, given the comment about averaging with the neighbours green will be overrepresented in the average. An additional (smaller) factor is that the colour filters aren't perfect, and green in particular often has some signficant sensitivity to wavelengths that the red and blue colour filters are meant to pick up.
edit: One other factor I forgot, green photosites are often more sensitive than the red and blue photosites.
Plus human eye is more sensitive to green than other channels
Green is not a creative colour.
Is this you? If so, my wife wonders what camera and software you used!
That's crazy.