1. Apparatus for processing image data comprising processing means, input means and display means, wherein said image data is defined by a plurality of data processing nodes arranged in a hierarchical structure and said processing means is configured to perform the steps of: generating a first image frame comprising a plurality of components by means of processing said plurality of data processing nodes; outputting said first image frame to said display means; receiving, via said input means, first user input data indicating one of said plurality of components; selecting a first data processing node considered to be appropriate to said indicated component; generating a second image frame comprising said plurality of components and further comprising tools relevant to said first data processing node; and outputting said second image frame to said display means.