1. A method of correcting white balance in a digital image, the method comprising: determining a number of grey blocks in the digital image according to geometric distortion criteria, each block comprising a subset of the plurality of pixels of the image, said number of determined blocks being less than a predetermined value; processing the digital image to generate an intermediate image; determining a number of grey blocks in the intermediate image according to the geometric distortion criteria; scaling one or more colour channels of the intermediate image by respective reference gain values derived in accordance with a grey world process performed on the intermediate image; and applying the respective reference gain values to the intermediate image, whereby an image with a corrected white balance is obtained.