[mapserver-dev] Re: RFC for XMP metadata support

thomas bonfort thomas.bonfort at gmail.com
Thu Jul 7 11:35:15 EDT 2011

How involved would it be to set this metadata in the PNG tXMP tag
through libpng?
Going through libgdal has the inconvenience that you loose the
quantization/paletization, along with the fact that you'll be
requiring an additional write to the disk before sending to the

Or maybe the xmp users are confined to non png formats, and in that
case this isn't a concern ?


On Thu, Jul 7, 2011 at 17:29, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
> No concerns, questions?
> On Mon, Jul 4, 2011 at 9:10 AM, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
>> Devs,
>> I've prepared a draft RFC for adding embedded metadata into output
>> images produced by MapServer.
>>  http://trac.osgeo.org/mapserver/attachment/ticket/3932/ms-rfc-7X.txt
>> I'm looking for feedback now before I number and commit it and ask for
>> a vote. Here's the preamble so you don't have to click:
>> XMP is the "extensible metadata platform" [1]_ which allows the
>> embedding of metadata information across a wide range of document and
>> image formats: PNG, GIF, JPEG, PDF, etc. XMP was originally developed
>> by Adobe [2]_ and is supported across their product line. It is now
>> being increasingly included in other standards for metadata embedding
>> and supported by tools for viewing image information (e.g. exiftools).
>> Creative Commons has standards for using XMP to embed commons
>> licensing [3]_ in images and other document, including a specific
>> creative commons schema. One of the challenges of advertising
>> licensing and terms of use in WMS and other web mapping services is
>> that the terms are usually advertised separately from the actual
>> content. So a WMS service might specify terms in the Capabilities
>> document, but the images themselves will be unmarked. Embedding
>> license URLs inside the images themselves using a standard marking
>> allows organizations to be unambiguous about the conditions attached
>> to their content.
>> The goal of this change is to allow users the option of embedding XMP
>> metadata in their MapServer output using an open source XMP utility
>> library.
>> .. [1] http://en.wikipedia.org/wiki/Extensible_Metadata_Platform
>> .. [2] http://www.adobe.com/products/xmp/overview.html
>> .. [3] http://wiki.creativecommons.org/XMP
>> .. [4] http://libopenraw.freedesktop.org/wiki/Exempi
>> Thanks,
>> Paul
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