lib/PHPExif/Exif.php
public function getIso()
    {
        if (!isset($this->data[self::ISO])) {
            return false;
        }

        return $this->data[self::ISO];
    }
public function getIso()
    {
        if (!isset($this->data[self::ISO])) {
            return false;
        }

        return $this->data[self::ISO];
    }
Returns the ISO speed

@return int|boolean