{% load wagtailimages_tags %}

{% if image_a != image_b %}
    {% if image_a and image_b %}
        {# Image has changed #}

        <div class="preview-image deletion">
            {% image image_a max-165x165 class="show-transparency" %}
        </div>

        <div class="preview-image addition">
            {% image image_b max-165x165 class="show-transparency" %}
        </div>

    {% elif image_b %}
        {# Image has been added #}

        <div class="preview-image addition">
            {% image image_b max-165x165 class="show-transparency" %}
        </div>

    {% elif image_a %}
        {# Image has been removed #}

        <div class="preview-image deletion">
            {% image image_a max-165x165 class="show-transparency" %}
        </div>

    {% endif %}
{% else %}
    <div class="preview-image">
        {% if image_a %}
            {% image image_a max-165x165 class="show-transparency" %}
        {% else %}
            <img>
        {% endif %}
    </div>
{% endif %}