Re: DPX reader vs. Northlight scans with infra-red pass

On Tue, 26 Aug 2008, Lewis Saunders wrote:

> First off thanks for the great DPX support, gm is very useful for all
> kinds of things :)

I am glad to hear that.

> I sometimes work with images which include a dust-busting pass from a
> Northlight scanner.  Currently gm isn't reading these correctly.

I have known about this since the format's conception.  It 
disappointed me deeply since GraphicsMagick already had 
standard-compliant one bit read/write working properly at the time 
but FilmLight decided to invent their own one bit format.  Several 
errors were made when designing this format.

> Interested to hear if anyone else uses these and if 1bit elements are
> (or even can be) supported.

I know that the dust channel is definitely being used by some 
software.  I saw an impressive demo of it's use several years ago.

It is likely pretty easy to update GraphicsMagick so that it will read 
this format.  It could ignore the extra channel, or it could use the 
one bit depth plus the "NL CLEAN MATTE" description to decide that it 
must be in the alternate format.  The main problem comes when writing 
since then GM would need to know if it should write this non-standard 
channel format and it needs to know that the alpha channel is 1 bit.

Do you have any advice regarding how GraphicsMagick should behave with 
such files?

Bob
======================================
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/


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