Hide feature image in selected pages

Can anyone help? I would like to be able to hide (i.e. not display) the feature image for selected pages.

Basically, I still want to be able to add a feature image to a page, so that it is displayed in another ‘portfolfio’ page (which draws in all feature images from pages within a specific category (I am using Ninja Pages plugin to add categories to pages), but for some of these pages, I don’t want the feature image to display in the page itself, for formatting reasons.

Any idea how I could go about this? Many thanks in advance.