"Simon" == Simon Budig writes:
Simon> Roland Roberts (roland@astrofoto.org) wrote:
>> I'm trying to write write a script-fu to automatically take a
>> finished image and produce a set of scaled images for display
>> on a web site. The learning curve for this is rather steep....
Simon> If it is just about scaling and/or do simple adjustments to
Simon> the image you might want to look at the imagemagick
Simon> tools. Usually these are better for simple tasks and the
Simon> learning curve for these is not steep at all.
I haven't played with ImageMagick, so I'm not sure how good a job it
does when rescaling. I've been using the GIMP because it's
downsampled images look pretty good, at least as compared to using the
netpbm tools.
Plus, I do most of my final editing in the GIMP---I create a set of
layers that overlay information onto the base image to be used as a
web rollover (see, for example,
http://www.astrofoto.org/gallery/constellations/view.html?con=her for
a recent example). Since I'm already working in the GIMP, I figured
I'd just add the feature there rather than have to fire up another
tool. I already have to do preliminary photo adjustments with a
Windoze tool (Picture Works Pro) since I want to work with
16-bits/color until near the end.
Scheme is not the problem, per se (hey! I learned Scheme 20 years ago
sitting in class with Abelson and Sussman *before* they printed the
book). It's all the GIMP stuff and the SIOD idioms that keep tripping
me. That and 20 years of messing more Emacs lisp than Scheme....
>> There appears to be an idiom that I can't figure out, a series
>> of lines like this:
>> (original-layer-for-darker #f)
>> what is the "#f"?
Simon> Just a shortcut for '(), or FALSE. #t would be 1 or TRUE.
Simon> However, I think these values are not used at all. They
Simon> appear in the declaration of variables and are unused
Simon> default values.
Okay, thanks. I'm not sure why the author did that; I would have just
written
(let* ((...)
original-layer-for-darker ...)
Anyway, I have the basic rescaling of a copy working and it loops over
the set of sizes I specify. I'm now adding code to copy all of the
layers instead of just the background layer as well as to copy layer
attributes correctly. I figured out, by trial and error, that
whatever it was wasn't important for me.
roland
