OK, please allow me to better explain my view. Please, try to get the point
and don't stick to possible unproper words, due to my different mother
tongue and my poor expression capabilities.
I wrote:
First, I agree that blown highlights can just be another way to show the
right part of the histogram.
That's OK. Here I can think of a "scene histogram" (if I can call it that
way), which is the "true" brightness distribution of the scene,
irrespectively of sensor exposure latitude and camera settings. Let's say
that the scene has its own and normal brighness distribution, so that a
capable sensor in a well set camera could reproduce it properly.
The picture histogram (which is what you get on the LCD) can (or cannot)
match the scene histogram, depending on dynamic range and the set exposure.
An overexposed picture will force a lot of scene details having different
brightness levels to be reproduced as pixels with the same brightbness level
(255, in a scale ranging from 0 to 255)
However, that's not always true: just think of a bright sky in a corner of
a backlit building almost filling the picture: the histogram could well
describe the light distribution within the backlit building and you'll be
fooled by a perfect histogram missing the sky (far right, outside the
histogram scale).
I'd rewrite it as follows:
Just think of a bright sky in a corner of a backlit building almost filling
the picture: the histogram could well describe the light distribution within
the backlit building and you'll be fooled by a good looking histogram hiding
the poor rendition of the sky (whose brightness levels should be outside the
histogram, on the right but are blown out, hence compressed on the right end
of the scale)
In this case, you'll get some (not so many) pixels showing up stuck on the
right side of the histogram, while they "should be" distributed outside it
on the right, if only the picture histogram could be either widened (wider
exposure latitude) or shifted to the right (exposure compensation). You can
get more latidude by shooting RAW, or you can shift the histogram scale by
compensating exposure, so that highlights having different brightness are
properly reproduced as pixels having different brightness.
In my opinion, the blown highlights should be tuned for "whiter than
white" (i.e. any level outside the histogram, on the right). This way,
they would perfectly complement the histogram and you won't risk to forget
a bright area whose brightness is far above a nice balance of shadow
levels (depicted by the histogram you are tuning with exposure).
I'd rewrite it as follows:
In my opinion, the blown highlights should be tuned for "whiter than white"
(i.e. any pixel having 255 brightness value, while its true level could be
higher, hence outside the current histogram, on the right). This way, the
blinking areas would perfectly complement the histogram and you won't risk
to forget small bright areas whose brightness is far above a nice balance of
large shadow areas (depicted by the histogram you are tuning with
exposure).
Of course, all above is intended for getting a correct reproduction of
brightness levels. The photographer can always choose not to do so for
creative purposes.
Dario
