An image processing function is selected via a graphical user interface (GUI) 902 that receives input commands from manually operated input means 102-103, 106 configured with activation means. Image data 707, 1206 is selected by placing a pointer 905 operated by the input means over its representation 919 within said GUI 902 and activating said activation means. In response to a translation 1301, 1303, 1402 of said representation 919 over a hierarchical representation 925 of said function within said GUI 902, said function is initialised according to said hierarchy with said selected image data 1206 as default data. In response to said initialisation, said GUI 902 is updated. In response to deactivating said activation means, said function is configured for processing said image data according to input received from said input means. The updated representation 1403 of said function includes a representation 919 of said image data 1206.