1. A method of producing a desired digital image of at least one desired face by a computer comprising: providing to the computer a digital image of at least one original face, wherein an original face comprises a foreground region drawn according to a set of guidelines; providing at least one face image from external sources; for the original face within the digital image, selecting a corresponding face image (selected corresponding face image) from among the face images from external sources; for the original face within the digital image, modifying the selected corresponding face image (modified corresponding face image); and replacing the original face within the digital image with the selected and modified corresponding face image at a desired position and a desired size within the digital image to produce the desired digital image of the desired face, wherein the set of guidelines comprises defining the original face as the foreground region drawn within the digital image to resemble and represent the desired face, defining the original face as the foreground region surrounded by other (foreground and/or background) regions and/or edges within the digital image, defining the original face as the foreground region with a distinctive edge wherein the distinctive edge separates the original face from the other regions within the digital image, defining a position of the original face drawn within the digital image as the desired position of the desired face, defining a size of the original face drawn within the digital image as the desired size of the desired face, defining the original face as the foreground region with majority of an area in a unanimous colour, defining the original face as the foreground region containing facial features, wherein the facial features and the foreground region of the original face are separated by different colours or edges, defining the facial features as comprising two eyes and one mouth, defining the two eyes as similar in size to each other, defining each of the two eyes to be in a unanimous colour, defining the mouth as bigger in size than each of the two eyes, defining the mouth to be in a unanimous colour, defining an arrangement of the two eyes and the mouth within the original face, as similar to an arrangement of eyes and mouth of a real human face, defining the sizes of the two eyes and the mouth relative to corresponding sizes of the original face, as similar to sizes of the eyes and the mouth of a real human face relative to the corresponding sizes of the real human face, and defining an upright position of the original face as a position where the two eyes are lying horizontally, with the mouth lying below the two eyes.