*For Mark, Rob, Maris, Pete, Cathy, and others who've shown interest and
leadership in Grain-Aliasing & Noise:
I'm in the process of experiments on one of two negs/pictures with *extreme*
color noise, and reporting on same. I thought it would take a day or so, but
that's probably what the Architect of Rome thought, too--- *Wrong!* ;-)
Here's a brief "Conclusions Synopsis" of the work so far--
......................................................
Of five techniques suggested by Filmscanners members, the success rate
(which relates to this picture *only*, BTW) rank this way:
1) Using LAB colors to isolate and blur "runaway pixels." There's a tendency
to mottle colors, but it's largely acceptable if not in a broad, gradated
area. LAB is available only in the full version of PS, not PS-LE nor PS
Essentials, AFAIK. I'm experimenting with a work-around for PS-LE.
2) Defocusing. This seems to make the *sheer number* of off-color pixels
worse, when viewed in magnification, but they blend fairly well at *normal*
viewing size (whatever that is ;-) ). Detail-blurring is surprisingly
slight, and large details hold quite well. It's easily done in Vuescan,
although it takes a little bit of experimenting with the numbers. I used
+1.3 with decent results. Probably could use less.
3) Scanning the reverse (emulsion) side. This works in some cases (probably
because the focus is changed), and I've done it successfully on some slides.
It didn't work well on this particular neg.
4) Using History Brushes to work between 2 version of the same picture.
Originally suggested for removing dust & scratches or isolated color
problems, it also works for *limited* (sectional) grain-aliasing and noise.
"History" is also unavailable in PS-LE or Essentials, but using "Layers" is
a viable work-around.
5) Resizing and JPEGing. This also works in some cases, but didn't here. The
noise was too much, too coarse.
*Worth mentioning: Color-masking the pixels and changing their color--This
technique is easily do-able in Micrografx PP8, probably in other programs as
well. It's available in PS-LE, but very difficult to handle and not
satisfactory, AFAIC. In this particular picture, the "runaway pixels" again
were too numerous and too varied to make this a particularly viable option.
Intuitively (using "non-linear logic," that is), I can see that a "Mix &
Match" approach will probably produce the best results for retouching, since
every "problem picture" has its own idiosyncrasies. What's best for the
picture is going to be what's best for your work-style, and vice-versa. I'm
neither a professional retoucher nor an expert at the various Windows
imaging programs, but I'll try to help where I can. It seems appropriate (to
me) to answer questions here on the List for the benefit of others who are
interested in retouching "noise." For the complete report (available at End
of Week, unless it goes into the tubes again), contact me off-list. Sorry, I
don't have a website.
Best regards--LRA
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