Magento – How to export gallery images using dataflow profiles onto different columns or otherwise

I did the following steps:

• convert to utf8
• remove empty "sku" column
• rename "artnr" to "sku"
• set column "type" to "simple" for all rows
• clear column "image" and "small_image": "?" => ""

And now the import tells me "Processed 100% 11/11 records", "Imported 11 records". All green, all good but the new products are not listed in the catalog.

I guess I am still missing some columns. If that does not help it would be worth a new question.

This is how I eventually solved my problem:

class Mage_Mymodule_Model_Catalog_Convert_Adapter_Product
    extends Mage_Catalog_Model_Convert_Adapter_Product
{
    /**
     * Load product collection Id(s)
     */
    public function load()
    {
        parent::load();

        $filters = $this->_parseVars();

        if (isset($filters['hasImage'])) {
            $hasImage = (bool)$filters['hasImage'];

            try {
                if (!($entityType = $this->getVar('entity_type'))
                || !(Mage::getResourceSingleton($entityType) instanceof Mage_Eav_Model_Entity_Interface)) {
                    $this->addException(Mage::helper('eav')->__('Invalid entity specified'), Varien_Convert_Exception::FATAL);
                }

                $collection = $this->_getCollectionForLoad($entityType);

                if ($hasImage) {
                    $collection
                        ->addAttributeToFilter('image', array('notnull'=>'', 'neq'=>'no_selection'))
                        ->addAttributeToFilter('small_image', array('notnull'=>'', 'neq'=>'no_selection'))
                        ->addAttributeToFilter('thumbnail', array('notnull'=>'', 'neq'=>'no_selection'));
                } else {
                    $collection
                        ->addAttributeToFilter('image', array('no_selection', 'null'))
                        ->addAttributeToFilter('small_image', array('no_selection', 'null'))
                        ->addAttributeToFilter('thumbnail', array('no_selection', 'null'));
                }

                /**
                 * $collection is not a reference, so we need to pass the product IDs
                 * to $this->setData() so that our attribute filters are applied.
                 */
                $entityIds = $collection->getAllIds();
                $this->setData($entityIds);
            } catch (Exception $e) {
                $message = Mage::helper('eav')->__('There was a problem filtering by `hasImage`. Error: %s', $e->getMessage());
                $this->addException($message, Varien_Convert_Exception::FATAL);
            }
        }

        return $this;
    }
}

I'd love to know how I can use $this->setJoinField or parent::setFilter or $this->setJoinAttr to do the same thing, as the parent class does for qty and price. I'll leave my answer unchecked for a few days to see if someone can help me find a better answer.