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Image::Magick scale smaller makes file size bigger

 
 
Gary Mayor
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      02-14-2004
Hi,
I know this should be in the modules group but as there seems to be a
lack of anyone else having this problem I thought i'de better give it
better coverage.
The problem is i'm using Image Magick to create thumbnails smaller
images out of large ones. 99% of the time this works great but there's
1% where the thumbnail has a bigger file size then the original image
and that I can't understand. The code i'm using is below and I hope
someone knows what this might be. I've tried resizing and saving the
images in gimp and the sizes turn out correct. Also if I compress the
image the size does decrease but why would a image with no compression
turn out bigger than the original. I also tried adding the icmp or
whatever it was to the code but that didn't make any difference. How can
this be anyone know?

Thanks

Gary

my $imager = Image::Magick->new;
die unless ref $imager;

my $status = $imager->Read("$infile");
print "Read: $status\n" if $status;

$height = $imager->Get('height');
$width = $imager->Get('width');

my $ttwidth = 100;

my $tbheight=1;
my $tbwidth=1;
my $fixed=$ttwidth;
my $scalefix=1;
my $scalefactor=$width/$fixed;
$tbheight=$height/$scalefactor;
$tbwidth=$fixed;

$count++;
$original[$count] = $cfile;
$status = $imager->Write(filename=>"$dir/$cfile");

$imager->Scale( width=>$tbwidth, height=>$tbheight );

$imager->Set(Quality=>$compression);

$new[$count] = "$outfile";
$status = $imager->Write(filename=>"$dir/$outfile",compression=>'JPEG');
 
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gnari
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      02-14-2004
"Gary Mayor" <(E-Mail Removed)> wrote in message
news:c0lgit$hs5$(E-Mail Removed)...
> Hi,
> I know this should be in the modules group but as there seems to be a
> lack of anyone else having this problem I thought i'de better give it
> better coverage.


there are a lot of other groups with much greater coverage, where these
questions are equally off-topic.

> The problem is i'm using Image Magick to create thumbnails smaller
> images out of large ones. 99% of the time this works great but there's
> 1% where the thumbnail has a bigger file size then the original image
> and that I can't understand.


that is entirely possible. when making a thumbnail, the sofware might
be doing a lot of processing to make the smaller image recognizable.
this may include playing with color depth or dithering. the rsulting
image may not compress as effectively as the original

> ... Also if I compress the
> image the size does decrease but why would a image with no compression
> turn out bigger than the original.


i do not know what you are talking about. was the original jpeg with
0 compression?

anyways some of the graphics newsgroups might be a better place
for this kind of questions. (unless, of course, if this only happens
with Image::Magick , but not the Imagemagick commandline tools)


gnari



 
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