Re: sizing down an uploaded photo

joe user <[email protected]>
Newsgroups gmane.comp.java.sun.servlet
Message-ID <[email protected]>
--- "Carter, Scott" <[email protected]>
wrote:
> I am hoping that someone using servlets has
> encountered this problem.  I
> have a web site where user's can upload photos, but
> after the servlet
> uploads the file I would like it to also resize the
> deminsions of the
> picture and the quality (size).  Has anyone run into
> this problem?

Yes.  There are several options.  Sun has a package
which manipulates 2d images in various ways.  I have
not tried that one, however.  The one that I have used
is called JMagick, which is a Java wrapper for
ImageMagick.  You can download both from
www.imagemagick.org.

The advantage of JMagick is that it supports an
amazing number of formats, is quite fast, and allows
fine control over image transformation.  For example
you can choose different scaling algorithms, you can
transform the color map in different ways, etc.

The disadvantage is that it uses JNI.  The
disadvantages of JNI are the same as the disadvantages
of C itself: there probably are buffer overflows
lurking in there, and if there is a bug in ImageMagick
which attempts to write to unallocated memory (the
joys of C) it will crash the entire JVM itself.
Instead of throwing an exception which is then caught
and then displays as an error page, the JVM just
instantly dies (no cleanup) and users see "server is
refusing connections on port 80".

I hope that Sun or someone else comes out with a
high-performance pure Java image manipulation package
that is as powerful as Imagemagick.  Until then I am
stuck with IM.

I realize that the Sun solution does support plugins,
so I could write my own handlers for various image
types, but I don't want to spend time writing that
kind of stuff.


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