Add background image to footer section in shopify

shopify-footer-bgimage.liquid

===== CSS =====
footer {
    background-image: url('{{ section.settings.bg_image | img_url: 'master' }}');
    background-size: cover;
    background-position: center;
}

===== In section settings =====
    {
      "type": "image_picker",
      "id": "bg_image",
      "label": {
        "en": "Background Image"
      }
    }