davesrose wrote in post #17102934
No, our brains don't perform WB: our eyes sense different color temperatures based on light intensity of daylight, and whether cone photoreceptors are being active. Cameras are completely different technologies.
If some on here want to believe DR in photography is only the SNR ratio of the sensor, so be it. Even though the absolute definition for imagery is the ratio between highest intensity of light (or tone) vs lowest, you're free to believe otherwise.
The eyes measures color. But the main part of our color constancy ability happens in the cortex, where the perceived color gets normalized both based on total intensity of the different wavelengths and based on knowledge of expected colors for different subjects.
So it's a bit like having a camera that knows the color of grass, roses, rust, ... and then adaptively calibrates the color channels to match the expected colors. Our cameras right now can't add that step. They can only try to measure the relations between color channels.
And this is why the brain fails with a printed photo. It picks up stimuli from the room and then expects the print to also use the same color temperature as the other subjects in the room. Don't let the eyes see the room, and then the brain can manage to perform WB of the print. Seeing both the room and the print, the brain notices when "white" has a different color temperature than "white" in the room.
And this ability of your brain to adapt allows you to add colored filters in front of your eyes and after a while adapt your color perception to reduce the effect of the color filters - and then you instead gets surprised by the results when you remove the color filters.
In the end, the cortex is able to perform quite a lot if interesting things, like the McCollough effect where you can get long-time effects after having seen colored patterns. And if you worked for a long time with the old-time green monitors you could then when you went out suddenly see white cars as pink. So in the end, the brain isn't flawless.
So once more - our cameras can match what our eyes can do. But they can't present the resulting image in a way that behaves the same as our cortex would expect the real nature to behave.