[Tig] Scanity in 16bit

Bob Friesenhahn bfriesen at simple.dallas.tx.us
Mon Nov 10 15:32:48 GMT 2014

On Mon, 10 Nov 2014, Carl Skaff via Tig wrote:
> Hi all
> Maybe this forum is a faster way to get support:
> I'm trying to scan in 16bit on my Scanity... but the DPX comes out in the
> wrong "channel order".
> Instead of the normal RGB it seems as it is BGR, I need to swap Red and
> Blue to make it look correct.
> Any ideas?

The DPX 2.0 specification (SMPTE 268M-2003) is a bit unclear/ambigious 
and vendors have accidentally or intentionally produced formats which 
result in wrong channel order as compared with the DPX 1.0 
specification and original Cineon system.

Original DPX put all data in 32-bit words so the 16-bit samples would 
be packed into 32-bit words which might be big/little endian.  Due to 
interpretation (and likely influence from TIFF), Filmlight decided to 
output 16-bit DPX as a linear array of 16-bit samples rather than 
packed into 32-bit words.  This changes the apparent order.  While 
16-bit DPX dates from the original Cineon system, a Filmlight scanner 
was used to produce the original STEM scans used as basis for DCI 
development, and 16-bit was not common before that time so Filmlight's 
approach has become the common way to store the data.

I paper I wrote about the DPX 2.0 specification confusion may be found 
at "http://www.simplesystems.org/users/bfriesen/dpx/dpx-issues.pdf".

Unless you can cause your scanner to output samples differently, you 
are faced with post-processing all the files (e.g. GraphicsMagick can 
do that) or hopefully telling the DPX reader to re-order the samples.

Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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