Return-Path: <warmerdam@pobox.com>
Received: from bee.skynet.be (bee.skynet.be [195.238.2.102])
        by twentyeight.skynet.be (8.12.9/8.12.9/Skynet-MAILSTORE-2.14) with ESMTP id i0NJP1JD030873
        for <joris.at.lebbeke@skynet.be>; Fri, 23 Jan 2004 20:25:01 +0100
        (envelope-from <warmerdam@pobox.com>)
Received: from sabre.velocet.net (sabre.velocet.net [216.138.209.205])
        by bee.skynet.be (8.12.9/8.12.9/Skynet-IN-2.32) with ESMTP id i0NJOkTG026100
        for <joris.at.lebbeke@skynet.be>; Fri, 23 Jan 2004 20:24:50 +0100
        (envelope-from <warmerdam@pobox.com>)
Received: from pobox.com (H156.C195.tor.velocet.net [216.138.195.156])
	by sabre.velocet.net (Postfix) with ESMTP
	id CC3921385E1; Fri, 23 Jan 2004 14:24:44 -0500 (EST)
Message-ID: <401174FE.3010008@pobox.com>
Date: Fri, 23 Jan 2004 14:24:46 -0500
From: Frank Warmerdam <warmerdam@pobox.com>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.5a) Gecko/20030718
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
Cc: Joris <joris.at.lebbeke@skynet.be>,
   Tiff mailing list <tiff@remotesensing.org>
Subject: Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB
References: <Pine.GSO.4.44.0401231316420.29988-100000@scooby.simplesystems.org>
In-Reply-To: <Pine.GSO.4.44.0401231316420.29988-100000@scooby.simplesystems.org>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-UIDL: 7f69a16b8120bca49bd5fca3229ee191

Bob Friesenhahn wrote:
> On Fri, 23 Jan 2004, Frank Warmerdam wrote:
> 
>>I am by no means an authority on the TIFF specification.  My interpretation
>>of the file in question is that a sensible application should render the
>>first band in greyscale and ignore the 2nd and 3rd since they are extra samples
>>with no meaning attached.  Without the ExtraSamples tag, I think an application
>>should assume the file contains 3 greyscale bands which might be drawn in any
>>number of ways.  One way would be to draw 1 band, and give the user the ability
>>to flip through to see the 2nd and 3rd.  Another would be to just treat them
>>as RGB (as many multispetral imaging packages will do with the first 3 bands
>>of multispectral data).
> 
> 
> I am no TIFF authority either.  I aggree with your summary.  The extra
> samples could mean almost anything.  More than likely the correct
> intepretation of the extra samples depends on the vendor extension
> tags that libtiff warned about. :-)

Bob,

Those are GeoTIFF tags. I *know* what the extra samples are, but it isn't
clear at all from the tags.

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
and watch the world go round - Rush    | Geospatial Programmer for Rent


