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January 2006
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2006.01.03 16:37 "Re: Strip Vs Tile", by Joris Van Damme
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 You may be preserving data that is no longer valid after your operations.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