{# Below image field from view o/p #}
{{ fields.field_books_theme_pic.content }}
{# Creating a Field URI post setting up relationship to image field fields.uri.content gives uri format eg:- public://image.jpg #}
{{ fields.uri.content|striptags|trim }}
{# and this gives the image uri for src ref #}
{{ file_url(fields.uri.content|striptags|trim) }}

{% set url = fields.field_books_theme_pic.content|render|striptags %}
{{ url }}