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Lets you adjust the white point of the render, meaning the the yellow to blue color cast range (lower K values make the render bluer or "cooler", higher K values make it more yellow or "warmer").
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Controls the green to magenta color castrange. Emitters in the real world not only emit bluer or more yellowish light, but can also emit a more greenish light, especially fluorescents. For this reason a complete white balancing tool also needs to control the green to magenta color cast in a photo. Negative values add a green tint, positive values add a magenta tint.
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