Handling of overexposure on digital cameras
What happens when your picture is overexposed? It seems nobody knows. Sure,
it gets white. Well, not quite... People usually seem to forget that
B
overexposure can happen in each of the colour channels (usually red, green,
blue) separately. In the first place, this means that just looking at your
histogram is not enough to determine whether your picture is well exposed.
Even if there is nothing on the very right, one or more channels may be
overexposed. This happens most often in pictures of red flowers. Some
flowers are extremely bright red, and while the camera's light meter and the
histogram say it's all right... the result is washed out reds. I remember
some people wondered why they didn't get proper details in bright flowers.
An ugly (probably overexposed) picture of a rose.
No, this flower is not orange, but pure
red! In this example it actually looks pretty, but in some cases it looks
pretty bad. I am curious as to why this happens. I've seen it on other
cameras too.
Also look at the red border surrounding the flower, which is an
effect of demosaic interpolation (a case of chromatic aliasing). I should
note that film also has this problem of chromatic aliasing: strange borders
appear around extreme colour contrasts (such as bright red against bright
green) that sometimes look cartoonish or `fantasy'-like. In some cases, extra
colours even appear, such as an extra yellow line along an extreme red-green
contrast border.
A pink sunset.