Форум

<?php

\Bitrix\Main\Loader::includeModule('iblock');
$rsElement = \Bitrix\Iblock\ElementTable::getList(array(
    "filter" => Array(
        "IBLOCK_ID" => 10,
        "ACTIVE" => "Y",
        "!DETAIL_PICTURE" => false
    ),
    "select" => Array(
        "IBLOCK_ID",
        "ACTIVE",
        "DETAIL_PICTURE_FILE_SUBDIR" => "DETAIL_PICTURE_FILE.SUBDIR",
        "DETAIL_PICTURE_FILE_FILE_NAME" => "DETAIL_PICTURE_FILE.FILE_NAME"
    ),
    "runtime" => array(
        new \Bitrix\Main\Entity\ReferenceField(
            'DETAIL_PICTURE_FILE',
            \Bitrix\Main\FileTable::getEntity(),
            array('=this.DETAIL_PICTURE' => 'ref.ID'),
            array('join_type' => 'LEFT')
        )
    )
));

echo "<pre>";
print_r('Количество элементов: ' . $rsElement->getSelectedRowsCount());
echo "</pre>";

while ($arElement = $rsElement->fetch()) {
    $strImageUrl = 'https://site.ru/upload/' .
        $arElement['DETAIL_PICTURE_FILE_SUBDIR'] .
        '/' .
        $arElement['DETAIL_PICTURE_FILE_FILE_NAME'];
}