[Geopackage] Geopackage Digest, Vol 13, Issue 18

Patrick van Dijk patrick.van.dijk at gmail.com
Wed Jun 24 09:46:31 EDT 2015


This is what it looks like in the Image Editor of SQLite Professional.
When I extract the image and view it in Microsoft Photo Viewer it seems to
be fine (see sqlite_whitehorse.jpg)

When viewing Whitehorse in our application (Spatial Workshop), which is
based on .NET/C# it renders fine, apart from the blackmess on the edge
(which I think should be transparent).

Regards,

Patrick

On Tue, Jun 23, 2015 at 6:00 PM, <
geopackage-request at lists.opengeospatial.org> wrote:

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> Today's Topics:
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>    1. Re: Displaying Geopackage Raster data (Even Rouault)
>       (Jeff Yutzler)
>    2. Re: Displaying Geopackage Raster data (Even Rouault)
>       (Pepijn Van Eeckhoudt)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 23 Jun 2015 10:00:12 -0400
> From: Jeff Yutzler <jeffy at imagemattersllc.com>
> To: geopackage at lists.opengeospatial.org
> Subject: Re: [Geopackage] Displaying Geopackage Raster data (Even
>         Rouault)
> Message-ID:
>         <CACuR0KvLi+qRzTLt2Gi0yEuj+vki9+=
> RLJDmcxhOJFcihaw3xA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> >
> > 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.
> https://github.com/opengeospatial/geopackage/issues
> Thanks,
> Jeff
>
> --
> Jeff Yutzler
> Image Matters LLC
> Mobile: (703) 981-8753
> Office: (703) 428-6731
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> Message: 2
> Date: Tue, 23 Jun 2015 17:43:56 +0200
> From: Pepijn Van Eeckhoudt <pepijn at vaneeckhoudt.net>
> To: Jeff Yutzler <jeffy at imagemattersllc.com>
> Cc: geopackage at lists.opengeospatial.org
> Subject: Re: [Geopackage] Displaying Geopackage Raster data (Even
>         Rouault)
> Message-ID: <D42BDFBF-A98F-4E8B-A2F4-A12D9D9555AA at vaneeckhoudt.net>
> Content-Type: text/plain; charset="utf-8"
>
> > 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.
> > https://github.com/opengeospatial/geopackage/issues <
> https://github.com/opengeospatial/geopackage/issues>
> > Thanks,
> > Jeff
> >
>
> Hi Jeff,
>
> I believe this is related to
> https://github.com/opengeospatial/geopackage/issues/104 <
> https://github.com/opengeospatial/geopackage/issues/104>. The images in
> the ERDC file are 4 channel CMYK ones. Strictly speaking these are not
> valid JFIF files since JFIF requires 1 (Y) or 3 channel (YCbCr) images and
> specifies the RGB <-> YCbCr conversion formulas that should be used.
>
> I?ve extracted and attached one of the images from the dataset <
> https://cloud.githubusercontent.com/assets/225326/8309554/6187e18c-19cb-11e5-9713-7d0f8143c8be.jpg>
> and attached it to the linked issue. That hopefully makes it a bit easier
> to analyse. I also dumped the metadata from that file using JPEGsnoop (see
> below). That clearly shows this being a 4 channel image.
>
> CMYK in JPEG seems to be an Adobe specific extension. Looking through the
> libjpeg code (see jdapimin.c#default_decompress_parms) it recognises a JPEG
> as being CMYK if it has 4 channels and contains an Adobe specific bit of
> metadata in an APP14 segment. The best spec I could find for this is
> http://www.aiim.org/documents/standards/PDF-Ref/References/Adobe/5116.DCT_Filter.pdf
> <
> http://www.aiim.org/documents/standards/PDF-Ref/References/Adobe/5116.DCT_Filter.pdf>
> which was referenced from https://issues.apache.org/jira/browse/IMAGING-89
> <https://issues.apache.org/jira/browse/IMAGING-89>
>
> For maximum interoperability, GeoPackage should probably stick to JFIF,
> but that?s just my 2 cents.
>
> Hth,
>
> Pepijn
>
>
> JPEGsnoop 1.7.3 by Calvin Hass
>   http://www.impulseadventure.com/photo/
>   -------------------------------------
>
> <snip>
>
> *** Marker: SOF0 (Baseline DCT) (xFFC0) ***
>   OFFSET: 0x0000008C
>   Frame header length = 20
>   Precision = 8
>   Number of Lines = 256
>   Samples per Line = 256
>   Image Size = 256 x 256
>   Raw Image Orientation = Landscape
>   Number of Img components = 4
>     Component[1]: ID=0x01, Samp Fac=0x22 (Subsamp 1 x 1), Quant Tbl
> Sel=0x00 (C)
>     Component[2]: ID=0x02, Samp Fac=0x11 (Subsamp 2 x 2), Quant Tbl
> Sel=0x01 (M)
>     Component[3]: ID=0x03, Samp Fac=0x11 (Subsamp 2 x 2), Quant Tbl
> Sel=0x01 (Y)
>     Component[4]: ID=0x04, Samp Fac=0x22 (Subsamp 1 x 1), Quant Tbl
> Sel=0x00 (K)
>
>  <
> https://cloud.githubusercontent.com/assets/225326/8309554/6187e18c-19cb-11e5-9713-7d0f8143c8be.jpg>
> <
> https://cloud.githubusercontent.com/assets/225326/8309554/6187e18c-19cb-11e5-9713-7d0f8143c8be.jpg
> >
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