Disclosed is a method and a device, that includes a programmed data processor, to process image data. The method includes, for a plurality n of files each containing image data representing one of n images, selecting one file as a base file; selecting as a target file an image data file that is contextually-related file to the base file; comparing the target file and the base file to determine differences therebetween; and storing the target file as a reduced file that is a representation of differences between the image data of the target file and the image data of the base file. An image data file is selected as being contextually-related to the base file based on at least an image capture location, and/or on an image capture time, or based on a user input. Storing can be performed in a memory device that is a part of a wireless communications device, such as a cellular telephone or a personal communicator that includes a digital camera, such as a camera phone.