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May 2004
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2004.05.10 22:29 "Re: Tiff questions", by Bob Friesenhahn
On Fri, 7 May 2004, James Carroll wrote:
> Hi, I have a bunch of questions.
>
> I am exploring using TIFF support for my image server that also supports
> FlashPIX. The general idea is that the images are very large, and
> people want to zoom in and out, so I am trying (pyramidal) multiple
> levels of downsampled versions of the same image, all stored as
> jpeg-compressed tiles.
You might consider using the "Pyramid" TIFF scheme supported by
ImageMagick/GraphicsMagick ("PTIF" format). This scheme is a bit
FlashPIX-like.
The strategy is to store multiple resolutions (different scaled sizes)
of the image as frames of a multi-frame TIFF. Each frame is stored in
tiled TIFF format. This allows the resolution to be quickly selected,
and then a region may be efficiently extracted by reading the
associated TIFF tiles.
To prepare the image, ImageMagick/GraphicsMagick simply successively
reduces the image size and saves the result as a frame until the image
size reaches a minimum threshold.
Bob
======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us
http://www.simplesystems.org/users/bfriesen