protected function processAdditionalImages()
    {

        // load the store view code
        $storeViewCode = $this->getValue(ColumnKeys::STORE_VIEW_CODE);
        $attributeSetCode = $this->getValue(ColumnKeys::ATTRIBUTE_SET_CODE);

        // load the parent SKU from the row
        $parentSku = $this->getValue(ColumnKeys::SKU);

        // query whether or not, we've additional images
        if ($additionalImages = $this->getValue(ColumnKeys::ADDITIONAL_IMAGES, null, array($this, 'explode'))) {
            // expand the additional image labels, if available
            $additionalImageLabels = $this->getValue(ColumnKeys::ADDITIONAL_IMAGE_LABELS, array(), array($this, 'explode'));

            // initialize the images with the found values
            foreach ($additionalImages as $key => $additionalImage) {
                // prepare the additional image
                $artefact = $this->newArtefact(
                    array(
                        ColumnKeys::STORE_VIEW_CODE    => $storeViewCode,
                        ColumnKeys::ATTRIBUTE_SET_CODE => $attributeSetCode,
                        ColumnKeys::IMAGE_PARENT_SKU   => $parentSku,
                        ColumnKeys::IMAGE_PATH         => $additionalImage,
                        ColumnKeys::IMAGE_PATH_NEW     => $additionalImage,
                        ColumnKeys::IMAGE_LABEL        => isset($additionalImageLabels[$key]) ?
                                                          $additionalImageLabels[$key] :
                                                          $this->getDefaultImageLabel()
                    ),
                    array(
                        ColumnKeys::STORE_VIEW_CODE    => ColumnKeys::STORE_VIEW_CODE,
                        ColumnKeys::ATTRIBUTE_SET_CODE => ColumnKeys::ATTRIBUTE_SET_CODE,
                        ColumnKeys::IMAGE_PARENT_SKU   => ColumnKeys::SKU,
                        ColumnKeys::IMAGE_PATH         => ColumnKeys::ADDITIONAL_IMAGES,
                        ColumnKeys::IMAGE_PATH_NEW     => ColumnKeys::ADDITIONAL_IMAGES,
                        ColumnKeys::IMAGE_LABEL        => ColumnKeys::ADDITIONAL_IMAGE_LABELS
                    )
                );

                // append the additional image to the artefacts
                $this->artefacts[] = $artefact;
            }
        }
    }