Вытащить картинки, как свойство.

$arSelect = array( 'ID',  'IBLOCK_ID',    'PROPERTY_MORE_PHOTO',    'PREVIEW_PICTURE', 'DETAIL_PICTURE' );     
 foreach ($arResult["SECTIONS"] as &$arSection) 
{ $rsPhotoElements = CIBlockElement::GetList(array("SORT" => "ASC", "NAME" => "ASC"), 
array("IBLOCK_ID" => $arParams["IBLOCK_ID"], "SECTION_ID" => $arSection["ID"], "ACTIVE" => "Y"), false, false, $arSelect);         
$i = 4;        
while ($i && $arElement = $rsPhotoElements->GetNext()) 
{$photo = CFile::ResizeImageGet($arElement["DETAIL_PICTURE"], array('width'=>200, 'height'=>180), BX_RESIZE_IMAGE_PROPORTIONAL);
$arElement["PREVIEW_PICTURE"] = $photo['src'];
$arElement["DETAIL_PICTURE"] = CFile::GetFileArray($arElement["DETAIL_PICTURE"]); 
$arElement["PROPERTY_MORE_PHOTO"] = CFile::GetFileArray($arElement["PROPERTY_MORE_PHOTO"]);
$arSection["ELEMENTS"][] = $arElement; 
$i--; 
} 
} 

<div class = "fancybox_slider" id = "slider_gallery">
<?foreach($arResult["SECTIONS"] as $arSection):?>
<?foreach($arSection["ELEMENTS"] as $arItem):?>
<img src="<?=$arItem["PROPERTY_MORE_PHOTO_VALUE"]?>">
     <?endforeach;?>
    <?endforeach;?>
</div>