The histograms show that your exposure isn't anywhere near the
highlight saturation level, indicative of underexposure. If you had
given the photo another stop or so of exposure, you could have
adjusted the RAW converter's gamma curve to allow a much better
expression of mid- and low-range values (zone II to IV) without the
color noise when doing the conversion from linear gamma to RGB.
Jack's rendering shows the noise buildup that I see very clearly, a
little bit more exaggerated than simply using Levels or Curves
adjustments without masking and feathering like I was doing.
Remember that in linear gamma terms, HALF the quantized tonal space
is within 1 stop of the overexposure/saturation limit, the next
QUARTER of the total tonal space is within the next stop. In an image
which should have many tonal variations in the Zone II to IV range,
you need to give enough exposure to shove the remaining 1/4 of the
tonal values around in RGB conversion while minimizing noise to get a
smooth effect.
Imposing clipping limits on the 8bit RGB image to extend the tonal
space to Zone I and Zone IX the way it ought to be demonstrates the
fact that the image is underexposed by revealing the Zone II-Zone V
mid-range noise. You might be able to reprocess the RAW file with a
better set of adjustments to reduce that underexposure, since your
RAW file has quite a bit more data in it than this JPEG rendering.
Godfrey
On Aug 4, 2005, at 11:39 PM, Bruce Dayton wrote:
I'm a bit confused. I just looked at the raw histogram with two
different programs and neither of them show anywhere near
underexposure. I agree that the histogram doesn't come near the black
or white clip points. So how could it be underexposed? I'm hoping to
learn something here for future use.
Here is a link to the histograms. The first is from Capture One, the
second is from BreezeBrowser Pro. The way I presented it was without
any exposure compensation.
http://www.daytonphoto.com/junk/index.htm
I'd have been more comfortable with this if it didn't seem
underexposed. The histogram in this one shows little in way of blacks
and whites, and clipping it with Levels reveals all the underexposure
noise.
This is the last shot of Valley of the Gods that might be worth
showing. Since you all have been kind enough to give me your
feelings
on "The Pyramid", hopefully you will do so here.
This shot uses the haze as a way to convey shapes and distances.
Let
me know what you think.
http://www.daytonphoto.com/PAW/monumentvalley_0479a.htm
