Re: [MCN SIG: Digital Media] Uniiversal Photographic Digital ImagingGuidelines

Tue, 29 Nov 2005 13:21:29 -0500 (EST)

Tim Au Yeung wrote: 
Hi Matt,
 
  
So now we can begin compressing our TIFFs? The main reason I ask is that I
    
have heard a lot of really
  
bad arguments against compression in the past, and a lot of non-argument
    
(for example: "it's just not
  
done"). I want to know what the good reasons against it are.
    
  
For a small museum especially, that might save hundreds of thousands of
    
dollars in storage by reversibly
  
compressing RAW and TIFF files, and therefore be able to preserve where
    
otherwise it might not be able to
  
afford it, is compression acceptable? Or is it so unacceptable that nobody
    
should implement a repository
  
with compression?
    
Well -- since TIFF has entered into the books as an ISO standard (see
http://www.digitalpreservation.gov/formats/fdd/fdd000072.shtml), based on
the TIFF 6 spec, there isn't a strong reason to argue against it.
Now I get it. I wasn't arguing against tiff--just not understanding some things about it.
I don't
have a copy of the standard in front of me and what it specifies as a part
of the standard in terms of compression so if someone else wants to comment
but I suspect that compression is allowed as part of the specification.
If that's true, that's truly great. I will look into it. Thanks!

As Alan Newman pointed out, not all tools handle compressed TIFFs nicely. So that's an issue sometimes.
One thing to consider is the difference between ideal practice and
best-possible practice recommendations -- in a ideal situation, you
eliminate all complex encoding (including compression) so that the final
file is (as much as possible) almost human readable. That way, there is the
possibility of "deducing" the layout of the file without any sort of key or
guide. Realistically, this is a terribly inefficient way of storing data
(see XML for examples) that often conflicts with the on-the-ground
experience of practitioners. I wouldn't eliminate compression from the
toolbox of practitioners wanting to implement a repository as it may be
necessary (High definition video, for instance, is completely unrealistic to
store in an uncompressed form).

A final thing to note is that RAW files often already have compression,
I had no idea. Thanks.

--Matt
"matt 5.vcf" (missing attachment)

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