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To: Randolf Gladish <randy@sensor.com>
Cc: tiff@sgi.sgi.com, krs@kampsax.dk
Subject: Re: TIFF Tags for remote-sensing 
In-Reply-To: Your message of "Tue, 19 Apr 94 16:54:41 EDT."
             <CMM.0.90.4.766788881.randy@topaz.sensor.com> 
Date: Fri, 22 Apr 94 11:03:24 +0200
From: "Karsten Spang" <krs@kampsax.dk>
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>I was wondering if there has been any work regarding the use of TIFF
>to store multispectral data sets. Most TIFF implementations place severe
>(for MS data) restrictions on the number of samples per pixel (bands)
>usually 3 or 4. This is completely inadequate for remote-sensing.

In principle there is no restriction on the number of samples in a TIFF
image. All the samples must have the same resolution, though. (I seem to
recall that the far infrared band of Landsat only has half the resolution
of the rest)

The main problem is that there is no suitable value for the photometric
interpretaion tag. I suggest that you contact Aldus and request that a 
new value "Multispectral" is included in the next version. Alternatively,
you may want a private value. The tag has no default value, nor is it a
"required" field, thus you may simply omit it. This is "right" in the
sense, that multispectral data have no real colors per se, only when
you assign colors to the bands, the picture comes out in (false) colors.

                               Karsten

P.S. (just speculating) New values of the resolution unit tag may be also
beneficial to remote sensing applications, including pixels per meter
and pixels per kilometer. You may also want new tags for describing the
geographical area depicted, wavelenght intervals for each sample, ...
--------------------------------------------------------------------------------
E-mail: krs@kampsax.dk                                      Karsten Spang
Phone:  +45 36 77 22 23                                     Kampsax Data
Fax:    +45 36 77 03 01                                     P.O. Box 1142
                                                            DK-2650 Hvidovre
                                                            Denmark


