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From: Hib Eris <hib@hiberis.nl>
To: David Burken <dburken@comcast.net>
Cc: tiff@lists.maptools.org
Subject: Re: [Tiff] Is it possible to read a large tiff image in portions?
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Hi David,

On Thu, Jun 30, 2011 at 6:02 PM, David Burken <dburken@comcast.net> wrote:
> On 06/30/2011 11:21 AM, Hib Eris wrote:
>>
>> To avoid this, I would like to read and process the image in pieces,
>> how should I do this with libtiff?
>>
> I'll point you to an example. =A0Ossim is tile based under the hood. =A0S=
o all
> of our image readers have one purpose, to stuff a tile of image data like
> 256x256. =A0Since tiff can be many flavors I'd start at
> ossimTiffTileSource::getTile as it takes multiple paths.
>
> http://trac.osgeo.org/ossim/browser/trunk/ossim/src/ossim/imaging/ossimTi=
ffTileSource.cpp

Thanks for the example. It seems to me that there is no higher level
function in libtiff to accomplish what I want and that most people
solve this by resorting to using low level functions like
TIFFReadScanline(), TIFFReadEncodedStrip(), and TIFFReadTile().

I would like to avoid that. Using those functions means putting
knowledge about the tiff format into my application. I would like to
keep my application simple, I am no tiff expert and I would like to
shield myself and other maintainers of my application from any tiff
specification intrinsics. In my opinion, libtiff is the place for tiff
expertise, not in the applications using it.

Wouldn't it be a good idea to implement a function like
ossimTiffTileSourcce::getTile in libtiff?
Maybe call it TIFFReadRGBARectangle(). It seems lots of applications
could benefit from it.

Hib
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