my $width = $pic_cur ->{Width};
my $height = $pic_cur ->{Height};
my $aspect = $height / $width;

my $max_height = 100;
my $max_width = 200;

my $new_width = $max_width;
my $new_height = $max_width * $aspect;
if($new_height > $max_height) {
    # too high, so reduce width < max_width
    $new_height = $max_height;
    $new_width = $new_height / $aspect;
}
# else: height <= max_height