Blog Posts Widget Uses a Small Portfolio Size Image Instead of Full Size Image

are you familiar with inspecting the DOM? Look what is your portfoliobox-ID

use this to get influence on image source as a snippet in your child-theme functions.php:

function my_avf_newsbox_image_size( $image_size, array $args, array $instance ){
  if( $args['widget_id'] == ( 'portfoliobox-3' || 'newsbox-2' || 'newsbox-4' ) ){
    $image_size = 'full';
  }
  return $image_size;
}
add_filter( 'avf_newsbox_image_size', 'my_avf_newsbox_image_size', 10, 3 );

______________
just for INFO:
change full to what you like to have ( small, medium, large etc. pp.) you can find the names of the enfold image-sizes on functions.php lines 211ff:

$avia_config['imgSize']['widget'] 		= array('width'=>36,  'height'=>36);			// small preview pics eg sidebar news
$avia_config['imgSize']['square'] 		= array('width'=>180, 'height'=>180);		       // small image for blogs
$avia_config['imgSize']['featured'] 		= array('width'=>1500, 'height'=>430 );			// images for fullsize pages and fullsize slider
$avia_config['imgSize']['featured_large'] = array('width'=>1500, 'height'=>630 );			// images for fullsize pages and fullsize slider
$avia_config['imgSize']['extra_large'] 	= array('width'=>1500, 'height'=>1500 , 'crop' => false);	// images for fullscrren slider
$avia_config['imgSize']['portfolio'] 		= array('width'=>495, 'height'=>400 );			// images for portfolio entries (2,3 column)
$avia_config['imgSize']['portfolio_small'] = array('width'=>260, 'height'=>185 );			// images for portfolio 4 columns
$avia_config['imgSize']['gallery'] 		 = array('width'=>845, 'height'=>684 );			// images for portfolio entries (2,3 column)
$avia_config['imgSize']['magazine'] 	= array('width'=>710, 'height'=>375 );			// images for magazines
$avia_config['imgSize']['masonry'] 	= array('width'=>705, 'height'=>705 , 'crop' => false);		// images for fullscreen masonry
$avia_config['imgSize']['entry_with_sidebar'] = array('width'=>845, 'height'=>321);		        // big images for blog and page entries
$avia_config['imgSize']['entry_without_sidebar'] = array('width'=>1210, 'height'=>423 );		// images for fullsize pages and fullsize slider

or do you realy mean “widget” – this is kind of technical term.
I now think you are talking about the postslider – and the thumbnails shown on this.
But be carefull – if you got a big list of portfolio – and each got a full resolution – performance will suffer on that.

Try this snippet in your child-theme functions.php:
f.e. on archiv pages like categories :

function custom_post_featured_image_link( $image_link, array $current_post, $size ){
  if(is_tag() || is_archive()){
    $image_link = get_the_post_thumbnail( $current_post['the_id'], 'full' );
  }
  return $image_link;
}
add_filter( 'avf_post_featured_image_link', 'custom_post_featured_image_link', 10, 3 );

hm … i try to get what you have taken for the alb element inside that page.

First – if you use the blog post alb element to insert. There is on the Styling Tab the option “Preview Image Size”
there you can choose the image size.

At the moment i could not say if there is a filter to preset that image_size attribute

What you can do as “quick and dirty” solution is to have a child-theme postslider.php
But then you will have in all alb elements getting the infos from postslider.php the full resolution.

but on your example page i can see that the full image is taken for the source:
( click to enlarge – red underlined )