Godfrey DiGiorgi wrote:
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
Know what, Godfrey?
If I had to think of and consider all that [expletive deleted] before I
took a photo, I'd end up just sitting around playing with my - camera
all day long!
For those of you with a bachelors in photographic tecknique and Advanced
Zone System folderol, please enjoy yourselves.
Thanks for the advise...
keith
