Return-Path: <tiff-bounces@lists.maptools.org>
Received: from inas009.isp.belgacom.be (localhost [127.0.0.1])
        by inav012.isp.belgacom.be (8.12.11.20060308/8.12.11/Skynet-IN-AV-3.00) with ESMTP id l2GI6gRa003121
        for <joris.at.lebbeke@skynet.be>; Fri, 16 Mar 2007 19:06:42 +0100
        (envelope-from <tiff-bounces@lists.maptools.org>)
Received: from inmx016.isp.belgacom.be (inmx016.isp.belgacom.be [195.238.4.219])
        by inas009.isp.belgacom.be (8.12.11.20060308/8.12.11/Skynet-IN-AS-2.03) with ESMTP id l2GI6YaF027724
        for <joris.at.lebbeke@skynet.be>; Fri, 16 Mar 2007 19:06:36 +0100
        (envelope-from <tiff-bounces@lists.maptools.org>)
Received: from duke.maptools.org (r153.dmsolutions.ca [209.217.116.153] (may be forged))
        by inmx016.isp.belgacom.be (8.12.11.20060308/8.12.11/Skynet-IN-2.32) with ESMTP id l2GI6Xmb000947
        for <joris.at.lebbeke@skynet.be>; Fri, 16 Mar 2007 19:06:33 +0100
        (envelope-from <tiff-bounces@lists.maptools.org>)
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 l2GHrVPd026245;
	Fri, 16 Mar 2007 12:54:50 -0500
Received: from owl.phy.queensu.ca (owl.phy.QueensU.CA [130.15.24.27])
	by duke.maptools.org (8.12.11/8.12.10) with ESMTP id l2GHrTpc026242
	for <tiff@lists.maptools.org>; Fri, 16 Mar 2007 12:53:29 -0500
Received: from [130.15.24.88] (U88.N24.QueensU.CA [130.15.24.88])
	by owl.phy.queensu.ca (8.13.1/8.13.1) with ESMTP id l2GHrN11031865
	for <tiff@lists.maptools.org>; Fri, 16 Mar 2007 13:53:28 -0400
Mime-Version: 1.0 (Apple Message framework v752.3)
In-Reply-To: <200703161701.l2GH1cJO025192@duke.maptools.org>
References: <200703161701.l2GH1cJO025192@duke.maptools.org>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
Message-Id: <80446D61-1DAB-4995-977E-A4E7F5DDE2EC@owl.phy.queensu.ca>
Content-Transfer-Encoding: 7bit
From: Phil Harvey <phil@owl.phy.queensu.ca>
Subject: Re: [Tiff] How to identify maker notes IFD
Date: Fri, 16 Mar 2007 13:53:22 -0400
To: tiff@lists.maptools.org
X-Mailer: Apple Mail (2.752.3)
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.0.1
	(owl.phy.queensu.ca [130.15.24.27]);
	Fri, 16 Mar 2007 13:53:28 -0400 (EDT)
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.000021b9
X-MSP-STORE: Fri, 16 Mar 2007 19:06:50 +0100
Status:   

Hi Anurag,

On 16-Mar-07, at 1:01 PM, tiff-request@lists.maptools.org wrote:
> I am parsing Exif IFD and  want to provide proper handling for maker
> notes, but i am not able to identify either it's ordinary maker notes
> or maker notes IFD.
>
> Example for makenotes tags, it's written as
>
> 92 7c 00 07 00 00 0e ca  00 00 13 64
>
> So how can anyone sure that it's makernotes IFD? Even i know that it's
> maker note ifd, but not able to difrenciate with normal case.
>
> Is there any tags through which we can identify?
> How would I identify these two different cases?

This is not part of the TIFF specification.  The maker is free to  
write whatever he wants in these notes.

If you really need to parse makernote IFD's you will earn yourself a  
big headache, take my word for it.  To to this you will need to  
generate some smart algorithms which scan for things that look like  
IFD's and validate the entries as much as possible to test for proper  
IFD structure.  As well, you need an algorithm to determine what type  
of offsets are being used (absolute as TIFF, relative to maker notes  
position, or relative to IFD entry), and you must take into account  
that absolute offsets can be shifted if the makernotes are moved by  
some other dumb utility.  But even if you do this correctly, you will  
find the need to have special logic for individual camera models  
since each has its own quirks.

The struggle begins.

- Phil

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