Use 'where_exp' to filter images from static assets – way shorter than building an array with a loop! See answer by Yuri P here: https://stackoverflow.com/questions/45926668/how-do-i-create-an-array-from-a-forloop

jekyll_filter_images.html

{% assign slider_images = "" | split: ',' %}
{% for image in site.static_files %}
    {% if image.path contains page.image_namespace %}
        {% assign slider_images = slider_images | push: image %}
    {% endif %}
{% endfor %}

{% assign slider_images = site.static_files | where_exp: "item", "item.path contains page.image_namespace" %}