<?php $carousel = get_field('slaider-header'); if ($carousel):?>
<?php foreach( $carousel as $image ): ?>
<img src="<?php bfi_thumb($image['url'],array('width'=> 847,'height' =>300));?>" alt="<?php echo $image['alt']; ?>"/>
<?php endforeach; ?>
<?php endif; ?>
place of picture, output:
<img src="" alt="">