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Message-Id: <9310191540.AA00502@oxford.chez.sgi.com>
To: rjd@mda.ca (Robert Doerksen)
Cc: tiff@sgi.sgi.com
Subject: Re: Multi-spectral, Tiled, Compressed TIFF images 
Reply-To: Sam Leffler <sam@asd.sgi.com>
In-Reply-To: Your message of "Fri, 15 Oct 1993 11:47:03 PDT."
             <9310151847.AA19847@ mda.ca> 
Date: Tue, 19 Oct 1993 08:40:21 PDT
From: Sam Leffler <sam@oxford.chez.sgi.com>
Sender: tiff-owner@sgi.sgi.com

    To:  tiff@sgi.sgi.com
    Subject:  Multi-spectral, Tiled, Compressed TIFF images
    Cc:  rjd@mda.ca
    Date: Fri, 15 Oct 1993 11:47:03 PDT
    From:  rjd@mda.ca (Robert Doerksen)

    A project that we are working on produces the following type of image which we
    would like to store using TIFF.  The image consists of 7 separate bands 
    (eg: 3 visible wavelengths and four IR wavelengths) which can be stored on 
    separate pages within one TIFF file.  Each band has 16-bit pixels.  Each band
    is about 10k pixels wide by 20k pixels high, which we wish to process as 200
    1k x 1k tiles.  Also, the image will contain some very large regions of 
    black-fill (pixel value = 0), which we would like to remove with some form of
    compression.  The compression must be loss-less, since it is mandatory to 
    maintain the integrity of the pixel intensity.
    
    >From my reading of the TIFF 6.0 doc, it appears that each of the above criteria
    can be met with TIFF, but it is not clear if they can all be met at the same
    time.  In effect, what I am looking for is to use TIFF to store a:
    
    	multispectral, tiled, compressed image
    
    such that TIFF readers which are compliant with version 6.0 extensions can
    access the imagery.

Yes, you can store this sort of data in TIFF.  If you want to store more
than 4 channels of data then you'll need the v3.3beta code since until
then the library had a restriction that no more than 4 channels could be
stored.
    
    Also, will the SGI ImageVision library tools be able to store/retrieve files
    of the kind described above?
    
It should, but you should check with those folks directly.  I believe that
most IL users with this sort of data use another format that's more commonly
found in the image processing community.  I don't recall if that format has
compression though.

	Sam




