1. A method for adjusting image data defining an image, the method comprising: generating a saliency map for the image; establishing a global transformation based on the image data wherein establishing the global transformation comprises ignoring parts of the image data corresponding to image areas indicated by the saliency map as having low saliency or weighing parts of the image data corresponding to image areas indicated by the saliency map as having low saliency less heavily than other parts of the image data corresponding to image areas indicated by the saliency map as having higher saliency; and applying the global transformation to the image data.