Received: from mailgate002.isp.belgacom.be (mailgate002.isp.belgacom.be [195.238.6.87])
	by maildelivery018.isp.belgacom.be (Postfix) with ESMTP id 7463A3AC06B
	for <joris.at.lebbeke@skynet.be>; Thu, 17 Apr 2008 14:20:11 +0200 (CEST)
Authentication-Results: in.mx.skynet.be; dkim=neutral (message not signed) header.i=none
Received: from r153.dmsolutions.ca (HELO duke.maptools.org) ([209.217.116.153])
  by in.mx.skynet.be with ESMTP; 17 Apr 2008 14:20:10 +0200
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 m3HBvPO6020269;
	Thu, 17 Apr 2008 07:58:48 -0400
Received: from grenfell.avtechpulse.com (grenfell.avtechpulse.com
	[64.26.155.62])
	by duke.maptools.org (8.12.11/8.12.10) with ESMTP id m3HBvKFe020266
	for <tiff@lists.maptools.org>; Thu, 17 Apr 2008 07:57:20 -0400
Received: from localhost (localhost.localdomain [127.0.0.1])
	by grenfell.avtechpulse.com (Postfix) with ESMTP id 68ED86E0012;
	Thu, 17 Apr 2008 07:57:18 -0400 (EDT)
X-Virus-Scanned: amavisd-new at avtechpulse.com
Received: from grenfell.avtechpulse.com ([127.0.0.1])
	by localhost (server2.domain.avtechpulse.com [127.0.0.1]) (amavisd-new,
	port 10024)
	with ESMTP id 6LmnzkqQz3g4; Thu, 17 Apr 2008 07:57:07 -0400 (EDT)
Received: from [192.168.0.23] (dogbert.domain.avtechpulse.com [192.168.0.23])
	by grenfell.avtechpulse.com (Postfix) with ESMTP id 637806E0011;
	Thu, 17 Apr 2008 07:57:07 -0400 (EDT)
Message-ID: <48073B13.10709@avtechpulse.com>
Date: Thu, 17 Apr 2008 07:57:07 -0400
From: "Dr. Michael J. Chudobiak" <mjc@avtechpulse.com>
Organization: Avtech Electrosystems Ltd.
User-Agent: Thunderbird 2.0.0.12 (Windows/20080213)
MIME-Version: 1.0
To: "Joris Van Damme (AWare Systems)" <joris.at.lebbeke@skynet.be>
Subject: Re: [Tiff] efficient thumbnailing
References: <4805FE97.8010109@avtechpulse.com>
	<003301c8a050$a4f5d020$0202a8c0@awaredfg964ezf>
In-Reply-To: <003301c8a050$a4f5d020$0202a8c0@awaredfg964ezf>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
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>
Sender: tiff-bounces@lists.maptools.org
Errors-To: tiff-bounces@lists.maptools.org
X-UIDL: 000000000023ceae.00002bf6
X-MSP-STORE: Thu, 17 Apr 2008 14:19:02 +0200
Status:   

Joris Van Damme (AWare Systems) wrote:
> Dr. Michael J. Chudobiak wrote:
>> Is there an efficient way to generate thumbnails from tiff files?
> 
> Stating the obvious but much neglected, make sure you use all and any 
> thumbnails present in the file for starters.
> 
> One source of thumbnails or downsampled copies is the SubIFD child IFDs. 
> A less known and older (and regrettable and discouraged) way to encode 
> thumbnails, that is still in use today, is linking additional IFDs in 

Joris,

Thanks for the comments - but I have never trusted embedded thumbnails. 
In my experience, too many programs are unaware of them or handle them 
improperly for them to be trustworthy. (As a gThumb developer, I know 
that gThumb used to leave jpeg-exif thumbnails unchanged after rotating 
or cropping, for example.)

- Mike

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