How is an image displayed in pages in the blog package?

Hi,
I installed the blog package and it has nice images in many of its sample posts, such as Sunshine in the Hills.

However, when I edit the md file of this page, it does not seem to have any code to display the image:

===============================================

title: Sunshine in the Hills
date: 14:55 07/11/2014
published: true
author: Tasha Maxwell
taxonomy:
    category: blog
    tag: [journal, photography]

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec ultricies tristique nulla et mattis. Phasellus id massa eget nisl congue blandit sit amet id ligula. Praesent et nulla eu augue tempus sagittis. Mauris faucibus nibh et nibh cursus in vestibulum sapien egestas. Curabitur ut lectus tortor. Sed ipsum eros, egestas ut eleifend non, elementum vitae eros. Mauris felis diam, pellentesque vel lacinia ac, dictum a nunc. Mauris mattis nunc sed mi sagittis et facilisis tortor volutpat. Etiam tincidunt urna mattis erat placerat placerat ac eu tellus.

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Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec ultricies tristique nulla et m attis. Phasellus id massa eget nisl congue blandit sit amet id ligula. Praesent et nulla eu augue tempus sagittis. Mauris faucibus nibh et nibh cursus in vestibulum sapien egestas. Curabitur ut lectu...........................

===============================================

The Learn section of Grav says to use something such as:

Yet I dont see this in the md above.

How is this image displayed in the page if there is no md for it?

Thanks ahead of time

Not familiar with the md for this forum so my formatting is not well done.....
The forum post above shows !Alt Text but I pasted in more than that - I am sure you know what I mean.

The general Markdown code for displaying an image is ![Alt Text](file.jpg), and should be in the .md-file if defined in content. If it is not, then a template is picking up one or more of the images in the same folder as the .md-file and displaying them.

Thanks for heloing me out!@

Hmmm I do see now that the template is picking up the file BUT if I delete the image file then the page shows "ERROR"
If I place another image with another name in the same folder as the page, then I also get error.....

I would have thought that the template is picking up ANY image if it is in the same folder as the page and displaying it, but that is not the case.

Please help

Specifically I still do not understand how the theme displays an image in the page......

PS
This seems to be the code in the partial blog_item.html.twig file that is picking up the image:

    {% if header_image %}
        {% if header_image_file %}
            {% set header_image_media = page.media.images[header_image_file] %}
        {% else %}
            {% set header_image_media = page.media.images|first %}
        {% endif %}
        {{ header_image_media.cropZoom(header_image_width, header_image_height).html }}
    {% endif %}

I figured it out

If you delete or change the image, you need to resave the .md file, in order not to get an ERROR report.

That indicates that Grav needed to rebuild the page. When in development, always disable the cache and be sure to clear it after testing prior to upload so you are certain Grav is not displaying any outdated/cached information.