To testrun ISA, I created this campaign : https://tools.wmflabs.org/isa/campaigns/10
which is based on the images in the Commons cat https://commons.wikimedia.org/wiki/Category:Atlas_de_Wit_1698
This category contains a number of completely blank pages without any taggable things on them
When creating a campaign, it would be handy to be able to deselect these blank images (or any other images in the category that the campaing creator wants to leave out) from getting used in the campaign