1. A method of manipulating a two-dimensional digital input image using an image operator that represents a change in a lighting characteristic, wherein the method comprises: deriving a mapping from an association between characteristics of aligned two-dimensional digital images in a dataset and at least one score allocated to each of a plurality of the images in the dataset, each score representing a degree of the lighting characteristic in the image, and wherein the dataset of images comprises images of different subjects; calculating the image operator based on a score offset indicative of a desire to manipulate the lighting characteristic in the input image by a particular degree and the derived mapping, wherein the image operator and the input image are aligned; receiving a request comprising the score offset; and applying the calculated image operator to the input image based upon the received score offset to produce a manipulated input image which corresponds to the input image but with the lighting characteristic manipulated.