alt Hacker News> The human eye is most sensitive to green light,
This argument is very confusing: if is most sensitive, less intensity/area should be necessary, not more.
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Yeah, was thinking the same. If we're more sensitive, why do we need double sensors? Just have 1:1:1, and we would anyways see more of the green? Won't it be too much if we do 1:2:1, when we're already more perceptible to green?
Note that there are two measurement systems involved: first the camera, and then the human eyes. Your reasoning could be correct if there were only one: "the sensor is most sensitive to green light, so less sensor area is needed".
But it is not the case, we are first measuring with cameras, and then presenting the image to human eyes. Being more sensitive to a colour means that the same measurement error will lead to more observable artifacts. So to maximize visual authenticity, the best we can do is to make our cameras as sensitive to green light (relatively) as human eyes.
Since the human eye is most sensitive to green, it will find errors in the green channel much easier than the others. This is why you need _more_ green data.