My guess is that your TIFF files contain more than one image - TIFF files can be that way. For example, the smaller, uglier image might be the thumbnail or preview stored with the image file.ImageMagick gives you a way to access the single images in a sequence:

# from memory, untested:
my $img = Image::Magick->new();
my $res = $img->Read( filename => $filename );
die $res if $res;
my @images = @$img;
printf "Found %s image(s)\n", scalar @images;
for my $output_image (@images) {
  print "Writing $target";
  my $target = sprintf "test.%s.png";
  $output_image->Write( filename => $target );
  print "\n";
};
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