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From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
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To: Frank Warmerdam <warmerdam@pobox.com>
cc: Joris <joris.at.lebbeke@skynet.be>,
   Tiff mailing list <tiff@remotesensing.org>
Subject: Re: [Tiff] How to convert MINISBLACK to PHOTOMETRIC_RGB
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Date: Fri, 23 Jan 2004 13:15:03 -0600 (CST)
X-UIDL: 59657cabb404d307b76055d74ca17e20

On Fri, 23 Jan 2004, Frank Warmerdam wrote:
>
> In the remote sensing community we used (still?) sometimes call what is a
> "sample" in TIFF a channel.  Apparently it originally had something to do
> with comunications channels to the satellite or something.  Band is another

You are biased by your remote sensing background.  A sample is just a
sample. A sample is one unit of data.  Multiple samples can be used to
support image rows, strips, tiles, or planes.

The notion of "channels" is a way of thinking about raster images as
being comprised of one or more layered "planes".  So the term
"channel" is similar to a "plane".  Some interpretation of the
available (or selected) channels is used to compose the image that a
viewer actually sees. For RGB hardware, the red channel occupies the
red channel of the hardware, etc.

So, a channel is a collection of all of the samples which have the
same meaning.

Bob
======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us
http://www.simplesystems.org/users/bfriesen

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