Hello Manuel,
I am sorry but the image that you have provide us is from our demo site. Anyhow, this code is hardcoded in the themes file. For example you can find this code in this file: \components\com_easyblog\themes\timeless\blog.read.php Line: 97
<div style="text-align:center;">
<img src="<?php echo $blog->getImage()->getSource( 'entry' );?>" class="blog-image" style="margin: 0 5px 5px 0;border: 1px solid #ccc;padding:3px;" alt="<?php echo $this->escape( $blog->title );?>" />
</div>
Hope this will help.
Thanks.