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From: "Joris" <joris.at.lebbeke@skynet.be>
To: "Pallek, Bernie: #CIPO - OPIC" <Pallek.Bernie@ic.gc.ca>,
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Subject: Re: [Tiff] Strip Vs Tile
Date: Tue, 3 Jan 2006 17:37:34 +0100
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Status:   

Pallek, Bernie: #CIPO - OPIC wrote:
> > My Query is regarding the layout of Tiff Images.
> > When to save a Tiff image as Tiled and when to save
> > a Tiff image as Strip ??
> > While saving, should we consider the layout of the
> > original Tiff image which we opened ??
>
> The TIFF spec 6.0 recommends a strip size of 8K (before compression).

That is mainly because the TIFF 6.0 spec was written when
- most of us were playing in a 64 kilobyte yard
- tiling was relatively new those days

IMO, what Bob said makes a lot more sense. If you don't need tiles, use
strips. Saving large images (say over 4 kilopixels wide and high), you
need tiles. I should add that for certain color spaces and compression
modes, like black and white G3 or G4 compressed, it is customary to save
a single strip even if the image is somewhat bigger then 4 kilopixels.

As to the strip/tile size, these days, I would almost recommend 8
megabyte rather then 8 kilobyte. We've recently learned on the list that
Photoshop's new strategy is to use as large a buffer as is affordable on
the machine in the run-time circumstances (though I'm not sure how
exactly 'affordable' is defined), because it helps getting the best
possible compression ratio and saves IO calls and fragmentation.

> When saving data in general, IMO, you should try to preserve as much
> of the original "framing" as possible.  In other words, preserve
> byte-ordering, stripping, compression format, IFD layout, whatever
> offsets you can, and even any custom tags that your software may not
> understand or care about.

That is bad advice. Don't ever blindly preserve. You may be preserving
data that is no longer valid after your operations.


Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
Download your free TIFF tag viewer for windows here:
http://www.awaresystems.be/imaging/tiff/astifftagviewer.html

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