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Moved a parenthetical to a more sensible place
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David Richerby
David Richerby
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It's because the red channel has completely blown out, whereas the green channel hasn't. (Nor blue but that's not having any effect, here.)

Suppose the true colour of the car is five parts red to one part green (the box on the left, below). If you underexpose the photo, you might find that the red channel's running at 50% intensity and the green channel would be correspondingly at 10%. Expose an extra stop and that goes to 100% red and 20% green, still showing the correct colour. But now if you expose another stop on top of that, the green doubles again to 40% intensity but the red can't double to 200% – it's stuck at 100%. So you end up with 100% red versus 40% geen, which is a ratio of five parts red to two parts green: much more orange than the true colour (the box on the right): much more orange than the true colour.

enter image description here

You see the same effect in photographs of the sky on bright days: the blue channel gets to 100% before the green channel, so the sky turns more cyan than it should be.

It's because the red channel has completely blown out, whereas the green channel hasn't. (Nor blue but that's not having any effect, here.)

Suppose the true colour of the car is five parts red to one part green (the box on the left, below). If you underexpose the photo, you might find that the red channel's running at 50% intensity and the green channel would be correspondingly at 10%. Expose an extra stop and that goes to 100% red and 20% green, still showing the correct colour. But now if you expose another stop on top of that, the green doubles again to 40% intensity but the red can't double to 200% – it's stuck at 100%. So you end up with 100% red versus 40% geen, which is a ratio of five parts red to two parts green: much more orange than the true colour (the box on the right).

enter image description here

You see the same effect in photographs of the sky on bright days: the blue channel gets to 100% before the green channel, so the sky turns more cyan than it should be.

It's because the red channel has completely blown out, whereas the green channel hasn't. (Nor blue but that's not having any effect, here.)

Suppose the true colour of the car is five parts red to one part green (the box on the left, below). If you underexpose the photo, you might find that the red channel's running at 50% intensity and the green channel would be correspondingly at 10%. Expose an extra stop and that goes to 100% red and 20% green, still showing the correct colour. But now if you expose another stop on top of that, the green doubles again to 40% intensity but the red can't double to 200% – it's stuck at 100%. So you end up with 100% red versus 40% geen, which is a ratio of five parts red to two parts green (the box on the right): much more orange than the true colour.

enter image description here

You see the same effect in photographs of the sky on bright days: the blue channel gets to 100% before the green channel, so the sky turns more cyan than it should be.

Source Link
David Richerby
David Richerby
  • 1.3k
  • 10
  • 19

It's because the red channel has completely blown out, whereas the green channel hasn't. (Nor blue but that's not having any effect, here.)

Suppose the true colour of the car is five parts red to one part green (the box on the left, below). If you underexpose the photo, you might find that the red channel's running at 50% intensity and the green channel would be correspondingly at 10%. Expose an extra stop and that goes to 100% red and 20% green, still showing the correct colour. But now if you expose another stop on top of that, the green doubles again to 40% intensity but the red can't double to 200% – it's stuck at 100%. So you end up with 100% red versus 40% geen, which is a ratio of five parts red to two parts green: much more orange than the true colour (the box on the right).

enter image description here

You see the same effect in photographs of the sky on bright days: the blue channel gets to 100% before the green channel, so the sky turns more cyan than it should be.