[Tig] XYZ colorspace/workflows

Jim Houston jim.houston
Fri Apr 28 07:12:42 BST 2006


--
Thanks to oktobor for supporting the TIG
--
I think the header was the simplest version of tiff we could do.

The one that is probably most of interest as a format issue is the
choice of 1 rows/strip as the standard layout.  This was done
after testing a half dozen applications for compliance.
1714 rows/strip (full image)  also worked.   3 rows/strip
which is often a default value do not work everywhere.

Photometric interpretation as RGB color was a compromise since
there is no value set aside for XYZ.     XYZ is just a matrix
version of an RGB space, so the tag is appropriate if you are aware
of the difference between XYZ primaries and your own display primaries.
The actual  primary chromaticities field is wrong in the master because
it should really refer to the XYZ primaries  not the 'output-referred 
reference
primaries' which are also listed in the image description.

Here is a tiffinfo on a file from the master..


> TIFF Directory at offset 0x282c008
>   Image Width: 4096 Image Length: 1714
>   Bits/Sample: 16
>   Compression Scheme: None
>   Photometric Interpretation: RGB color
>   Target Printer: "DLP Cinema Projector"
>   Artist: "digital master by Pacific Title & Art Studio"
>   Date & Time: "02/09/2004 16:01:34"
>   Host Computer: "Linux RedHat 7.2 on i386, Windows XP on i386"
>   Copyright: "Digital Cinema Initiatives  (c) 2004   Available under 
> specific license."
>   Document Name: "StEM-mini-movie"
>   Image Description: "CIE XYZ photometric interpretation with gamma
> 1/2.6 transfer function. Color is output referred to digital 
> projector:  TI
> DLP Cinema Projector(2003) with ideal primaries red(x=0.6800 y=0.3200),
> green(x=0.2650,y=0.6900), blue(x=0.1500, y=0.0600)"
>   Make: "CIE XYZ master  Feb 09, 2004"
>   Model: "version 1.0"
>   Orientation: row 0 top, col 0 lhs
>   Samples/Pixel: 3
>   Rows/Strip: 1
>   Planar Configuration: single image plane
>   White Point: 0.314-0.351
>   Primary Chromaticities: 0.68,0.32 0.265,0.69 0.15,0.06
>   Software: Discreet 'Lustre', Shake, Pacific Title pt_resample and
> tiffdci


There is a document pending within SMPTE which will clarify the
parameters and metadata for the uncompressed DCDM using TIFF.

Jim Houston
Starwatcher Digital



On Apr 27, 2006, at 11:27 AM, Bob Friesenhahn wrote:

> --
> Thanks to oktobor for supporting the TIG
> --
> I believe that I am interested in learning more about the specific XYZ 
> TIFF format that Jim Houston invented for the DCI test film 
> (http://www.dcimovies.com/press/09-24-03.tt2) which may be purchased 
> from SMPTE on hard disk since I have heard that current JPEG2000 
> encoders targeting DCI format prefer this format as input.
>
> However, I may be misinformed ...
>
> Bob
>
> _______________________________________________
> Tig list - http://tig.oktobor.com/mailman/listinfo/tig
> TIG wiki: http://tig.colorist.org/wiki
>


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