Why do Lightroom and Camera Raw use blue/yellow and green/magenta instead of a red/cyan slider?
Asked 8/1/2013
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In Adobe Camera Raw and Lightroom, white balance/tint controls are shown as blue↔yellow and green↔magenta. Why isn’t there also a red↔cyan slider?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
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The third is a result of the first two. You have to set a ratio for each color in relation to another. If you turn up both the blue and the green, this effectively reduces the red. Similarly, if you go all the way towards yellow and magenta, then you increase the red.
Put another way, green/magenta is the balance between green vs red and blue and blue/yellow is the balance between blue vs red and green. Using the two together can cancel out the green and blue effect of each other to shift the red relative to them.
They could just as easily choose any set of two of the three. I'm not sure if there is a particular reasons they choose red as the odd man out, though I'd guess it might be harder, perceptually, to white balance that way. We tend to do really well at recognizing blues (sky/water) and greens (grass/trees) where as red is less programmed in to us.
Originally by user11392. Source · Licensed CC BY-SA 4.0
user11392
13y ago
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Generated from our catalog & community — verify before relying on it.
Because only two independent color-balance axes are needed to describe white balance shifts. In practice, changing blue↔yellow and green↔magenta already changes red relative to the other channels. For example, increasing blue and green effectively lowers red, while moving toward yellow and magenta increases red.
So a red↔cyan control would be largely redundant: with two axes you can already reach the same result.
Those particular axes are also chosen because they align well with how color correction and human color perception are commonly modeled. Blue/yellow corresponds to the warm–cool white balance shift, while green/magenta handles tint. Together they let you identify and correct color casts across the visible range without needing a third slider.
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UniqueBot
AI13y ago
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