Re: [APML] Scannning to Eliminating Developing Artefacts on Negatives

[Ray Butler <ray.butler@nuigalway.ie>]

Hi Mike,

I'd think that since the artefact has a colour which sets it apart from 
the rest of the B&W negative, then scanning in _colour_ and afterwards 
separating out the RGB colour channels could provide a way to get rid of 
it.

Depending on what software you use, you could apply some sort of 
operation which compares the values in the three channels and throws out 
any pixel which is deviant (darker on the negative/brighter on the 
positive). At any given position, you can afford to throw away 2 and 
only keep 1 pixel at worst, since it is a greyscale image and the 
genuine signal should be the same in all 3 channels (+/- noise). You 
might need to scale all three channels to the same average brightness 
first, so as to compare apples with apples.

Ray "who thinks that this would be easily done in IRAF or IDL, maybe not 
so easily in Photoshop and the like" Butler


M/S Heald wrote:

> Hello!  I’ve finally got some good 4x5 negatives from my camera.  I used 
> TMax 400 and E100G for color and I want to combine them after scanning. 
>  Unfortunately, there is a mild pink color in the middle of the TMax 400 
> black and white negative.  The stars look good otherwise.  There must 
> have been developer contact problems during development.  Since this is 
> a black and white negative, is there an easy way to scan this negative 
> so that the pink color in the middle of the negative is eliminated, or 
> can this be handled easier post-processing?  In such a case, should I 
> scan it as a black and white negative or a color negative in order to 
> make post-processing easier?
> 
>  
> 
>     Thank you and best regards.
> 
>  
> 
> Mike
> 
> 
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-- 
Dr. Ray Butler (ray.butler@nuigalway.ie || ray@physics.nuigalway.ie)
Lecturer, Dept. of Physics || Computational Astrophysics Laboratory
National University of Ireland, Galway, University Road, Galway, Ireland.
Tel: +353-91-524411 ext. 3788   FAX: +353-91-525700


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