Ah yes, got it.
I have adjust the sizes to 500 x 275. It’s within the code, you can find it by looking for this:
if ( $display_type == "masonry" || $display_type == "masonry-gallery" ) {
//$thumb_height = null;
$thumb_width = 500;
$thumb_height = 375;
}
I also change this:
$thumb_gallery = rwmb_meta( 'sf_thumbnail_gallery', 'type=image&size=sf-thumb-image' );
To this, to get the origional size uploaded:
$thumb_gallery = rwmb_meta( 'sf_thumbnail_gallery', 'type=image&size=full' );
As long as your image that you originally uploaded is large enough you can change those sizes and the image will be able to re-size. It looks like the slider images you have uploaded are