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October 1999

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1999.10.29 19:53 "TIFF scaling", by Tom Degerlia
1999.10.29 22:33 "TIFF scaling", by Tom Degerlia
1999.11.01 14:50 "TIFF scaling", by Tom Degerlia
1999.11.01 14:51 "TIFF scaling", by Tom Degerlia
1999.11.01 23:41 "Re: TIFF scaling", by Ulrich Von Zadow
1999.11.02 03:33 "Re: TIFF scaling", by Bob Friesenhahn

1999.11.01 14:51 "TIFF scaling", by Tom Degerlia


Thank you for the information.  My application is currently window's
specific, so I may be able to use the system function.  Can you recommend a
good resource (book or otherwise) for graphic algorithms?



Tom DeGerlia

-----Original Message-----
From: Eric Shapiro []
Sent: Saturday, October 30, 1999 7:53 AM
Subject: Re: TIFF scaling

>If not, what is a reasonably efficient way of implementing a
>scaling function?

If you want to be cross-platform, I think you have to roll your
own or find something in a book or on the 'net.

Almost all computer platforms these days have some sort of
bitmap scaling routines built-in. On the Mac, you just allocate
a second GWorld and call CopyBits(). Under Windows I think the
call is StretchDIBits() or something like that.

Depending on how you want to scale the image you may like or
dislike the choices made by the system routines, though. There
are a few different ways to stretch and shrink images. If you
need to be fast you do it the easy way. If they are cartoon-like
images, you might not need to average surrounding pixels. If they
are photograph-like images you may want to do something else. Line
drawings a different way. Etc, etc.

Any good graphic algorithm book should cover this.


 Eric Shapiro         
 Relium Corp.