Received: from mailgate010.isp.belgacom.be (mailgate010.isp.belgacom.be [195.238.6.3])
	by maildelivery020.isp.belgacom.be (Postfix) with ESMTP id 596757AC00F
	for <joris.at.lebbeke@skynet.be>; Fri, 11 Jan 2008 00:05:27 +0100 (CET)
Authentication-Results: in.mx.skynet.be header.from=shirahatti@gmail.com; dkim=permfail (body hash did not verify [TEST])
Received: from r153.dmsolutions.ca (HELO duke.maptools.org) ([209.217.116.153])
  by in.mx.skynet.be with ESMTP; 11 Jan 2008 00:05:26 +0100
Received: from duke.maptools.org (duke.maptools.org [127.0.0.1])
	by duke.maptools.org (8.12.11/8.12.10) with ESMTP id m0AMmFVI009704;
	Thu, 10 Jan 2008 17:48:53 -0500
Received: from rv-out-0910.google.com (rv-out-0910.google.com [209.85.198.186])
	by duke.maptools.org (8.12.11/8.12.10) with ESMTP id m0AMmCED009701
	for <tiff@lists.maptools.org>; Thu, 10 Jan 2008 17:48:13 -0500
Received: by rv-out-0910.google.com with SMTP id c27so782938rvf.9
	for <tiff@lists.maptools.org>; Thu, 10 Jan 2008 14:48:10 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma;
	h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references;
	bh=QToUO6g/3Ejw0aaV9y3advtHNB5FkmEb82gCRCwyiRA=;
	b=pypyyXym0C9KD+Tx0VnbdDiSJ9hMRZkK2ZoKgfsQDTiKL4ChOlsKlGtHlrv4PWMgx73ykMsY8Z7xzvcUxYf8Ys5OAhvhSP2wJ16xk2c6Lda3zMPQSWCPbg5+vXbu8vyK4XLOvl+8P4LPU6fRA1p6lS65hLVff7wJ4RnfhWFdEyA=
DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma;
	h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references;
	b=VnQ235sAEg64StmeW/M3+mTJzhXgo+trudv9hWzbHEZZmtnbsk8t2qKpNtYyR3Wh0V2U6IlISxh7EnrGgVDw2aMfcUr65pL6vNCw2IG1bQJc2fAEiJb/8fTPxqTqkxRlw2XP6wPLl4doxobFcCpSzJFzasnhewRXLlQRTF8ubRc=
Received: by 10.140.169.6 with SMTP id r6mr1552463rve.273.1200005290524;
	Thu, 10 Jan 2008 14:48:10 -0800 (PST)
Received: by 10.140.191.7 with HTTP; Thu, 10 Jan 2008 14:48:10 -0800 (PST)
Message-ID: <fb91ffe0801101448l52a29d76q3cf0fad4fb9987e@mail.gmail.com>
Date: Thu, 10 Jan 2008 14:48:10 -0800
From: "Nikhil Shirahatti" <shirahatti@gmail.com>
To: "Frank Warmerdam" <warmerdam@pobox.com>
Subject: Re: [Tiff] LibTiff..Reading partial strips
In-Reply-To: <4786976C.7030502@pobox.com>
MIME-Version: 1.0
References: <fb91ffe0801101103o3addbc5bhd6fb7234fbef1216@mail.gmail.com>
	<Pine.SOC.4.64.0801101531190.2557@freddy.simplesystems.org>
	<fb91ffe0801101340g1ea9c156h11b53e0d1aa7a03e@mail.gmail.com>
	<4786976C.7030502@pobox.com>
Cc: tiff@lists.maptools.org
X-BeenThere: tiff@lists.maptools.org
X-Mailman-Version: 2.1.4
Precedence: list
List-Id: TIFF and libtiff discussion <tiff.lists.maptools.org>
List-Unsubscribe: <http://lists.maptools.org/mailman/listinfo/tiff>,
	<mailto:tiff-request@lists.maptools.org?subject=unsubscribe>
List-Archive: <http://lists.maptools.org/mailman/private/tiff>
List-Post: <mailto:tiff@lists.maptools.org>
List-Help: <mailto:tiff-request@lists.maptools.org?subject=help>
List-Subscribe: <http://lists.maptools.org/mailman/listinfo/tiff>,
	<mailto:tiff-request@lists.maptools.org?subject=subscribe>
Content-Type: multipart/mixed; boundary="===============2025536618=="
Sender: tiff-bounces@lists.maptools.org
Errors-To: tiff-bounces@lists.maptools.org
X-UIDL: 000000000023ceae.000029d6
X-MSP-STORE: Fri, 11 Jan 2008 00:05:27 --22-99
Status:   

--===============2025536618==
Content-Type: multipart/alternative; 
	boundary="----=_Part_8892_12535570.1200005290559"

------=_Part_8892_12535570.1200005290559
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

ReadScanline doesn't really help me..OK let me rephrase the question...the
reason I want to read partial strips is:
lets say a strip is of length 1000. I want to read be able to read the strip
from 0 to 100, 101 to 200...and so on so I have 10 chunks of data.
The reason why I want to do this is to convert it to our internal structure
for further processing. One may argue why not use the tiles in
libtiff...because we are not guaranteed that the tiff is tiled (they may be
from anywhere)...Unfortunately the scan line also reads the whole scan
line...even though much less memory intensive doesn't serve  our goal...

On Jan 10, 2008 2:08 PM, Frank Warmerdam <warmerdam@pobox.com> wrote:

> Nikhil Shirahatti wrote:
> > I havent tried it..but the cautionary note that " It is not always
> > possible to do so due to decompression constraints" scares me. I also
> > read on the archive that "that *strip* * chopping* only works for
> > uncompressed  IFDs.". How common(or uncommon) is this? When would one
> > use compressed IFD's?
> >  The tiff's we get can be compressed or uncompressed formats and we have
> > to support them all. :)
>
> Nikhil,
>
> I think Bob means compressed images.  There is no such thing as compressed
> IFDs.  Compressed TIFF images are quite a common case, and fax compressed
> images are often one strip.
>
> In addition to "strip chopping", libtiff also has the TIFFReadScanline()
> function for reading strips one scanline at a time.  This operates without
> needing to read and decompress the whole strip at once.
>
> Best regards,
> --
>
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam@pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam<http://pobox.com/%7Ewarmerdam>
> and watch the world go round - Rush    | President OSGeo, http://osgeo.org
>
>


-- 
-----------------------------------------------------------------
Nikhil V Shirahatti
http://vision.cs.arizona.edu/nvs

------=_Part_8892_12535570.1200005290559
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

ReadScanline doesn&#39;t really help me..OK let me rephrase the question...the reason I want to read partial strips is:<br>lets say a strip is of length 1000. I want to read be able to read the strip from 0 to 100, 101 to 200...and so on so I have 10 chunks of data. 
<br>The reason why I want to do this is to convert it to our internal structure for further processing. One may argue why not use the tiles in libtiff...because we are not guaranteed that the tiff is tiled (they may be from anywhere)...Unfortunately the scan line also reads the whole scan line...even though much less memory intensive doesn&#39;t serve&nbsp; our goal...
<br><br><div class="gmail_quote">On Jan 10, 2008 2:08 PM, Frank Warmerdam &lt;<a href="mailto:warmerdam@pobox.com">warmerdam@pobox.com</a>&gt; wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div class="Ih2E3d">Nikhil Shirahatti wrote:<br>&gt; I havent tried it..but the cautionary note that &quot; It is not always<br>&gt; possible to do so due to decompression constraints&quot; scares me. I also<br>&gt; read on the archive that &quot;that *strip* * chopping* only works for
<br>&gt; uncompressed &nbsp;IFDs.&quot;. How common(or uncommon) is this? When would one<br>&gt; use compressed IFD&#39;s?<br>&gt; &nbsp;The tiff&#39;s we get can be compressed or uncompressed formats and we have<br>&gt; to support them all. :)
<br><br></div>Nikhil,<br><br>I think Bob means compressed images. &nbsp;There is no such thing as compressed<br>IFDs. &nbsp;Compressed TIFF images are quite a common case, and fax compressed<br>images are often one strip.<br><br>In addition to &quot;strip chopping&quot;, libtiff also has the TIFFReadScanline()
<br>function for reading strips one scanline at a time. &nbsp;This operates without<br>needing to read and decompress the whole strip at once.<br><br>Best regards,<br><font color="#888888">--<br>---------------------------------------+--------------------------------------
<br>I set the clouds in motion - turn up &nbsp; | Frank Warmerdam, <a href="mailto:warmerdam@pobox.com">warmerdam@pobox.com</a><br>light and sound - activate the windows | <a href="http://pobox.com/%7Ewarmerdam" target="_blank">
http://pobox.com/~warmerdam</a><br>and watch the world go round - Rush &nbsp; &nbsp;| President OSGeo, <a href="http://osgeo.org" target="_blank">http://osgeo.org</a><br><br></font></blockquote></div><br><br clear="all"><br>-- <br>
-----------------------------------------------------------------<br>Nikhil V Shirahatti<br><a href="http://vision.cs.arizona.edu/nvs">http://vision.cs.arizona.edu/nvs</a>

------=_Part_8892_12535570.1200005290559--

--===============2025536618==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

_______________________________________________
Tiff mailing list: Tiff@lists.maptools.org
http://lists.maptools.org/mailman/listinfo/tiff
http://www.remotesensing.org/libtiff/
--===============2025536618==--
