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Lecture 11: Radiometry (9)
joannejqi

Dealing with different spectral power distributions is an important part of auto white balancing in cameras. This is a good resource for learning about auto white balance: https://www.cambridgeincolour.com/tutorials/white-balance.htm

hannahmcneil

@joannejqi, what interests me the most about that is the manner in which we might get these unintentional color casts. More specifically, what determines whether you will get one shade over the other? I tried looking into it and it seems that auto white balance doesn't necessarily "know" what color the actual light is tinged (it uses a best guess algorithm in a limited range of color temperatures), so it might make mistakes. I feel like I might be misunderstanding something though. (I've also seen backlash from photographers who don't particularly like that feature!)

The stuff about mixed lighting (calculating average temperatures) was also pretty interesting.

nebster100

I was just wondering why fluorescent light has such a weird spectrum and how that would affect human beings in terms of how they view a room. Does anyone know any good resources to learn about this?

nebster100

I was just wondering why fluorescent light has such a weird spectrum and how that would affect human beings in terms of how they view a room. Does anyone know any good resources to learn about this?

Pinbat

@nebster100 The light emitted will still look white, but the weird emission spectrum comes from the emission by the plasma or the exciting phosphors on the surface of the tube (fluorescents are usually glass tubes with rare gas inside). Here's a source with some good starter info: https://www.comsol.com/blogs/calculating-the-emission-spectra-from-common-light-sources/

theandrewchan

Spectral distributions are super cool! We actually have a physical law describing how the spectrum of light radiated by an object changes as the object gets hotter or colder if we assume the object is an ideal blackbody. This means we can plug in the temperature of an object like a lightbulb and predict exactly what color the lightbulb will be. Read more at (https://en.wikipedia.org/wiki/Planckian_locus)

fywu85

I wonder how do we deal with situations where we have a mixture of different light sources. Do we simply add one on top of another or do they in fact interact with each other in a nonlinear way? I am also curious how spectrum of daylight shifts from morning to noon and from noon to dawn.

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