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[filmscanners] Scanner Noise Levels

  • To: lexa@lexa.ru
  • Subject: [filmscanners] Scanner Noise Levels
  • From: "" <HMSDOC@aol.com>
  • Date: Tue, 05 Mar 2002 13:21:42 EST
  • Unsubscribe: mailto:listserver@halftone.co.uk

I am not sure if I am going to be asking this in clear technical terms, but I 
will give it a whirl.

I am wondering about "acceptable" noise levels in film scanners, knowing that 
perfection can not be reached and  that the degree of perfection needed depends 
on what one wants to do with an image.  That said, I am using a Canon FS4000 
scanner and wondering about how much noise one should expect in  shadow areas.  
For example, I have a macro image of a rose and there are shadow areas within 
the swirl of petals, particularly in the central unopened ones.  The image, as 
displayed when opened in Photoshop appears quite good.  But as one zooms in, 
you can see that the dark area is not all really black pixels, but a good deal 
of black with lots of other dark  and random colors mixed in (if you look at 
the histogram of this red rose that fills the entire frame there is a single 
peak of blue and green channels near the black point which, I assume represents 
mostly these noise pixels).  How much should one expect......at what degree of 
 % "enlargement" in Photoshop should one start to!
 expect seeing these noise pixels in a 'good' scanner?  Other than just 
printing at different sizes is there a way to predict at what size print these 
will start to become visible on ink jet output?  Where does it become more than 
just a technical finding that you can see if you search for it?


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