On 05/08/00, ""Edward G. Orton" <[EMAIL PROTECTED]>" wrote:
> Has anyone got a tool which will take large, true colour pictures,
> and create thumbnails of them using a Perl script? I need something I
> can automate because I am assisting someone with an encyclopedia of
> flora, and there are hundreds of thousands of images to reduce. Most
> of the applications I can find can only convert relatively few images
> at a time, and cannot be automated.
>
> Thanks for any assistance that can be provided.
I'll provide a tool for you in exchange for monetary compensation :-).
Seriously. A professional-quality solution written in Perl or involving
Perl that will run mostly unattended and provides quality results (that
uses algorithms matched to the task etc) isn't a trivial matter. And
monetary compensation isn't a dirty word :-).
E.G, if you are completely reluctant to pay me for getting this together
for you, and want instead to do it yourself, there are many messages posted
about this sort of thing both to this list and other fora. Just a few days
ago on this list I think much the same question was answered (by me and
others). The Perl answer nearly always comes out much the same:
Image[Perl}-Magick. If you are talking truecolor images there isn't really
any other way to go that's "pure" Perl. More on that below, tho. Another
question is that your use of the term "density" is misleading, what you
want is resizing (or alternatively some would use "rescaling" or
"resampling" or "changing the image resolution [also can be misleading
tho]". What you want to do is take images of whatever resolution (which
only applies to printers, i.e. the screen as an output device is fixed at
its nom. "72 dpi" [actually a range anywhere from abt. 72 to about 96 dpi
for most displays] and dimensions (image width x image height measured in
pixels) and output a version adjusted to to a "bounding box" of whatever W
x H (say 128 x 128) and a resolution of ca.72 (dpi). Yeah, according to
documentation Image[Perl]Magick will do that, no, I haven't actually done
it using I[P]M, and I have reason to think it might not be the best way to
go (for me).
The "pure Perl" question: the thing is, Perl excels at orchestrating the
execution of external tasks and processes ("duct tape") and so why be bound
to a so-called pure Perl solution? I have used Perl for thumbnail
generation by having external console programs called in to do the actual
image data manipulations; while i know that there is overhead in making
many system calls, this is still IMHO a very valid option at the present
state of the art in Perl image processing.
Speaking of which this list isn't (as you noted) really the place to get
answers to questions like this, or at least to limit yourself to. May I
suggest comp.lang.perl.misc? Over there right now I see at least 5 threads
taking place which i pulled up using search params "image processing
+ImageMagick" [Remarq - www.remarq.com] . And there is a regular on that
and other USENET Perl Lists who is writing a book on Perl image processing,
I cannot divulge (as a early reviewer) any details about that (I agreed to
a confidentiality stipulation regardig code from that book) but in a few
more months it will be one to refer to on questions like this. The name to
look for is Martien Verbruggen (I am sure the stipulation doesn't cover my
merely mentioning his name).
If you aren't resizing your pics in real-time for dynamic serving (i.e.
CGI) but only going to do it once, then it doesn't matter all that much
what method (software) you use, does it? I think using even an app that
you've already tried (and found wanting in terms of how many it will do in
one go) but controlled batch-manager-style by Perl would get the job done.
Look at my website for more; my web content tends to focus on Perl &
imaging.
http://www.wonderstorm.com/techstuff/Perl_dex.html
HTH,
soren andersen
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