why does colors appear different trough Camera than in rl?

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why does colors appear different trough Camera than in rl?

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Answer 1

Human vision detects colours using three different types of “cone” cells in the eye, known as Long-, Medium-, and Short-wavelength-sensitive. These are loosely equivalent to “red”, “green”, “blue” … but we’ll come back to that.

Modern digital cameras and phone cameras also have separate pixels in their image-sensors which detect “red”, “green”, and “blue” light.

However, you have to think about what happens if you see spectral (“rainbow”) colours *between* the red/green/blue primaries. If you looked at a spectral orange colour, that activates both the Long (“red”) and Medium (“green”) cones in some ratio that depends on both the colour of the light *and* how the sensitivity of the cone-cell decreases as you move away from its colour of maximum sensitivity. The brain interprets that ratio of red and green signal from the eye as a particular shade of “orange”. Essentially the RGB filters in cameras have a different response to in-between colours than the human eye, and therefore do not “see” in-between colours in the same ratios.

A camera sensor’s RGB filters generally have less-overlap than the colour-sensors in the eye, which can result in the camera seeing the colours “pulled” more-towards the red/green/blue primary than the original colour. (This is very apparent if you ever try to take a photograph of the spectrum from a prism.) Real colours contain a whole mixture of different wavelengths in different amounts, so it all gets quite complicated to predict the exact effects.

Specifically the Long (“red”) sensor in the eye effectively* has some extra sensitivity in the very deep purple, whereas the red sensor in a camera doesn’t. This is why some purple colours look purple (similar to magenta) to people, but only come out blue on a camera.

You can get *very* specialist cameras which can capture colour exactly the same way as human vision, but they’re very expensive (£50k+), bulky, and slow – they move special filters in front of the sensor sequentially to capture the colours – and this filters are designed to replicate the exact sensitivity of the eye.

This is a complicated topic of *Colour Science*, and well beyond ELI5. Including the subtle differences between *LMS sensitivities* and *colour matching functions*. I’ve done my best to try and simplify.