A method is presented of determining powder data from photographs. With a microphotometer the density is measured in steps of 0.01° 2θ. These data are used by a computer program. With this program the background and the noise level are determined first. After the detection of the diffraction peaks, the peak positions and intensities are refined, a suitable model for the peak profile being used. A procedure is described for scaling of several photographs. The final results are illustrated with a comparison of 2θ values determined according to this method and the calculated values of the lattice refined with these data. The resulting data prove to be equivalent to the data obtained by conventional means. The computer program is written in FORTRAN