1. In a method for coding and decoding an image of an object which comprises the steps of: forming superposed, coded shadow images of the object by irradiating the object with radiation emitted in different directions from point sources of radiation, recording the superposed images on a recording medium, and subsequently decoding the coded images formed by convolving of the superposed shadow images with a function which is representative of the distribution of the point sources used to irradiate the object; the improvement wherein: the step of irradiating the object comprises irradiating the object with radiation which is emitted from point sources which are distributed in a regular matrix and are divided into at least three groups so that the position of the sources in a first combination of the groups is described by a first source distribution function and the position of the sources in a further combination of the groups is described by a second source distribution function and the sum of the autocorrelation functions of the first and second source distribution functions has a nonzero value at a single point and a zero value at all other points; the step of forming the coded images includes successively activating each of the groups of point sources to form a corresponding number of successive superposition images and the step of decoding includes the steps of convolving positives and/or negatives of the superposition images, with point image functions of the groups of sources to form convoluted images; and summing the convoluted images to produce a decoded image.