WWWBoard New Message: Message 250: Re: Noise on scans

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   Posted by Noise4000 on 11/10/02 at 11:13 AM

Subject:   Re: Noise on scans

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In Reply to: Re: Noise on scans posted by WWWBoard Administrator on 11/10/02 at 10:55 AM:


Yup my name is Simon - thanks for swift reply.

I guess I can understand grain on a 400 ASA film - but ilford FP4 film has a very small grain so I would be very much surprised if this was showing up.

There is a very good site:


which goes into a lot of detail about this - and his view is that the film grain is much smaller than can be resolved by a scanner - the effect we are seeing is produced by an interaction of the film grain and the scanning resolution.

His view is that scanning at a slightly lower res might make this grain aliasing disapear - so we are being peanalised for having a sharp 4000 dpi scanner!

So basically to make any use of the scans I have to downsample them and blur them! I guess I'd prefer not to have spent the 650 and just stuck to PhotoCD :-(


: Hi Noise4000 (do you have a name?),

: The illustrations on your site are excellent and revealing, and yes, it's grain! The sometimes unpleasant consequence of the CanoScan's extreme sharpness. You can see the identical pattern in the Photo CD scan: it is just softer. If it were noise it would be different. The Photo CD doesn't have as good resolution/detail as the CanoScan, hence less grain is visible. The print is REALLY soft. Camera shop prints are typically too soft to reveal grain-- this could be deliberate. I've had another person send me Kodak Gold 200 results-- it's a sharp but quite grainy film. I'll forward you his e-mail. There are software solutions, such as blur with threshold, and something new coming in Picture Window Pro ( http://www.dl-c.com ). I will have more to say later-- I may make it a little campaign to educate people about this phenomenon.


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