I wrote this for an online image gallery. I wanted the 'long' dimension to be no larger than 450 pixels, so my script needed to do the resizing before commiting the file to disk and I needed to write down the height and width attributes so that I could modify the HTML to display the image correctly. Here's my code:

# write the file to a temporary location
    my $tmp_loc = $TEMP_IMG_DIR . $image_name;
    my $whan;
    open($whan,">$tmp_loc") || die "Cannot write $tmp_loc $!";
    print $whan $temp_file_var;
    close($whan);


# Resize image and write it to the appropriate location
use Image::Thumbnail;
    my $t = new Image::Thumbnail(
        size       => 450,
        create     => 1,
        inputpath  => $tmp_loc,
        outputpath => $main_loc
    );

# Get the new size of the main image
use Image::Info qw(image_info dim);
    my $info = image_info($main_loc);
    my ($w, $h) = dim($info);
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$temp_file_var is holding the image.
At the end, the new image is written to the path in $main_loc and I have the width $w and the height $h of the new image.

I hope that you can modify this for your use!

oakbox