I have created and maintain Magento extension (responsive banner slider) but have run into an issue.
FO user who upgrade from a previous version these smaller images will need to be batch created for all existing banner images. But what I cant seem to find out is how to trigger a helper function that will perform this action and is only run once after the upgrade from the current version to the future version which where this functionality will be implemented. I know how to write upgrade / data scripts but this only allows for database manipulation. Can someone point me in the right direction on how to implement this.