Digital BW, The Print

Mike:  Thanks. I was afraid it was something like that.  The film is 
T400CN, which is supposed to scan better than traditional silver 
films. But its weakness is that the darker things get, the grainier 
it gets.

Since I posted the problem, I even tried scanning as a color slide, 
then inverting the image and desaturating through various color 
filters.  I got a slightly better initial image that was easier to 
tweak into the right tonal range.  But the problem remained--the 
images were virtually identical once I matched the first scan's 
curves.

Multiple-pass scanning did not help, either, so I guess it's just 
interaction between whatever's on the film and the scanner.

--Peter

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Nunan, Mike" 
<mike.nunan@c...> wrote:
> Hi Peter,
> 
> I don't know if this will make you feel any better, but your 
findings are
> depressingly familiar to mine with medium speed B&W film. You hit 
the nail on
> the head when you say that a darkroom print doesn't show the same 
problem --
> there is something happening in the interaction between the scanner 
and the
> film. Out of interest, if you compare 10x8 prints, both wet process 
and
> digital, is the digital print appreciably sharper? If so, you could 
soften the
> digital print slightly to average out the speckle and still end up 
with a
> print about as sharp as the traditionally made one. Not ideal, I 
know.
> 
> Anyway, here's my 2p theory about what causes the problem we're 
both seeing.
> Consider the grain structure in the developed film, on a 
microscopic level. It
> consists of clouds of stringy-looking metalic silver arranged very 
randomly.
> Kodak have a shortish article about all this, including some nice
> photomicrograph illustrations:
> 
> 
http://www.kodak.com/US/en/motion/students/handbook/sensitometric6.jht
ml
> 
> From that article:
> 
> "At magnifications where the eye cannot distinguish individual 
particles, it
> resolves random groupings of these particles into denser and less 
dense areas.
> As magnification decreases, the observer progressively associates 
larger
> groups of spots as new units of graininess. The size of these 
compounded
> groups gets larger as the magnification decreases, but the 
amplitude (the
> difference in density between the darker and the lighter areas) 
decreases. At
> still lower magnifications, the graininess disappears altogether 
because no
> granular structure can be seen"
> 
> Clearly each sensor site in your scanner's CCD is looking at a 
fairly small
> area. It can't resolve individual grains but it can certainly see 
small enough
> clumps that the amplitude will vary quite widely. (Referring to the 
article,
> each pixel of the sensor is behaving very much like the small 
aperture used to
> scan films when testing for RMS granularity.)
> 
> I believe we are seeing this effect right across our images, but we 
are less
> concerned about it in the high and mid tone areas because in 
traditional
> processes we always see a bit of grain there. However, when we see 
it in the
> shadows, our immediate reaction is to assume it's scanner noise. In 
fact, when
> scanning negs, the signal to noise ratio should be at its best in 
the shadow
> region of the image.
> 
> There are a couple of things that can help reduce the problem. We 
can soften
> the image post-scan as I suggested above, but none of us want to 
lose any hard
> won sharpness. Using a scanner with a more diffuse lightsource can 
make a big
> difference. Scanners such as Epson flatbeds do tend to give 
slightly softer
> images than dedicated film scanners, but more importantly their flat
> lightsources don't throw the grain structure into such sharp 
relief, meaning
> that the local variations in density are less dramatic.
> 
> Sorry if this doesn't help you get better results out of the 
equipment you
> already have. I mention these issues in the hope that discussion of 
them will
> eventually lead to better solutions being found. I have seen major 
exhibitions
> of digital prints by "big name" artists where shadow speckle has 
been visible,
> so it's not just us!
> 
> Best regards,
> 
> -= mike =-
> 
> -----Original Message-----
> From: Peter A. Klein [mailto:pklein@2...]
> Sent: 15 August 2004 10:35
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Shadow noise in scans
> 
> 
> Folks:  I frequently encounter shadow noise in my scans. I can 
> usually work around it, but I'm wondering if there is something I 
can 
> do--perhaps while scanning--to minimize it.
> 
> Have a look at this:
> http://users.2alpha.com/~pklein/temp/noise.jpg
> 
> This picture was taken with an M6TTL and CV 50/1.5 Nokton, on Kodak 
> T400CN rated 400.  It was taken in a dim reception hall, but the 
> subjects were illuminated by a shaft of light from some nearby 
large 
> windows, and I exposed for them, not the background.  The scanner 
is 
> a Canon FS-4000, run at 4000 dpi and driven by VueScan.  I scan to 
16 
> bit TIFF, and use Picture Window Pro in 16 bit mode for my 
editing.  
> The various versions of the picture are shown at 1/3 actual pixels.
> 
> The leftmost image is of the scan pretty much out of the scanner 
(I'd 
> spotted and cropped, but that's all).  You can see the noise in the 
> darkest areas.  This is the kind of noise I am often plagued with.  
> It tends to happen more often in available light pictures than well-
> lit outdoor shots.  It doesn't show much on a 5x7 quadtone print, 
but 
> is quite prominent on an 8x10.  And if I get the same picture 
printed 
> in a wet darkroom, the noise isn't there. 
> 
> The center image is what I ended up with after curves, contrast, 
and 
> sharpening (the latter using a mask so only the people were 
> sharpened, not the surrounding area.  I've dropped the background 
to 
> nearly jet-black, but there are still lots of noise speckles.  And 
> I've lost some gradation in the girl's hair.
> 
> The righthand image has been noise-filtered with NeatImage before 
> curves, etc.  I used it sparingly so it wouldn't soften 
> or "plasticize" the image too much.  It's helped, but the noise 
still 
> shows up--more in a print that on the screen.  I've found that most 
> of the time, when I use NeatImage or Picture Window's Despeckle 
> feature, I can only get rid of some of the noise before the image 
> gets messed up.
> 
> What might I try to get rid of this noise?  Is there anything can I 
> do to minimize it during the scan?  I've tried the multiple 
exposure 
> feature in VueScan, and it doesn't really help with this type of 
> noise.  
> 
> BTW, here's the whole picture.  This one is a reduction of the 
Costco 
> CD Jpeg I got when the film was developed.  They went way dark, so 
> you see no shadow noise (or detail).  
> 
http://users.2alpha.com/~pklein/JonAntionWedding/Show/JonAntionWedding
> /slide_13.jpg
> 
> Thanks,
> --Peter Klein
> Seattle, WA
> 
> 
> 
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