[Geopackage] Displaying Geopackage Raster data (Even Rouault)

Jeff Yutzler jeffy at imagemattersllc.com
Tue Jun 23 10:00:12 EDT 2015

> Date: Fri, 19 Jun 2015 20:37:49 +0200
> From: Even Rouault <even.rouault at spatialys.com>
> To: geopackage at lists.opengeospatial.org
> Subject: Re: [Geopackage] Displaying Geopackage Raster data
> Message-ID: <201506192037.50245.even.rouault at spatialys.com>
> Content-Type: Text/Plain;  charset="utf-8"
> Le vendredi 19 juin 2015 18:46:03, Burken, David a ?crit :
> > Hi Phillip,
> >
> > I can read with the ossim code but they are  using jpeg tiles with a CMYK
> > compression and I can't get the colors correct.  I think the gdal folks
> > complained about this also.  The original Whitehorse gpkg which they said
> > was incorrect I could read just fine.  We usually do pnga for the edge
> > tiles that are partial and plain old JCS_RRG jpeg for interior tiles.  I
> > thinks they are using the "K" for alpha maybe.
> I tried your hypothesis since GDAL does CMYK -> RGB conversion, by
> considering
> CMY as RGB without conversion, but the result is complete garbage, whereas
> the
> current CMYK -> RGB conversion produce just "weird" colors... One
> hypothesis I
> didn't test is to take the reverse value of K since this is often a source
> of
> ambiguity...
I'm not 100% clear on what the actual issue is here. Is there a
problem with the spec? If so, please write up a ticket and I will make sure
the SWG takes a look at it.

Jeff Yutzler
Image Matters LLC
Mobile: (703) 981-8753
Office: (703) 428-6731
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