django-imagekit get image height from template

Question

In my template file i have:

{% generateimage 'myapp:catalogitem' source=product.image -- class="itemimage" %}

Style for this image:

div.pricelist-item img.itemimage {
                float: left;
                max-width: 40mm;
                margin-bottom: 5mm;
                height: auto;
            }

My goal is to pass that image height to another template tag. Problem is that in database there is a lot of different size images. How can i get that generated image height in pixels?