[vox-tech] Using Convert to Resize Images

Jim Angstadt vox-tech@lists.lugod.org
Wed, 19 Feb 2003 14:15:06 -0800 (PST)


Hi All,

For the past few months I've been using convert,
inside a perl script, to resize all jpg images in a
dir, using this syntax:
   `convert -geometry $geo $from $to`;

According to the man page, this uses a default quality
of 75, on a scale of 0(worst)..100(best).  Generally I
have been satisfied with that quality, but sometimes
not.

So, I would like the option of a higher image quality,
while still staying within the image size constraints
of the web page design.

When I use this syntax:
   `convert -geometry $geo -quality $qual $from $to`;
for various values of $qual ( 75 or 85 or 95) there is
no obvious difference in the 'visual' quality of the
images.  Also, each comparable file has the same size.
 And running diff on any two files yields no
difference.

So, the files do not seem to be effected by the
'-quality' option.  Are the quality and geometry
options mutually exclusive?  What am I missing?

Thanks,
Jim

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