In a digital Radon transform processor, a Radon projection of a pixellated digital image is obtained by providing the digital image in raster scanned format, and, for each image pixel, determining a processor storage location which corresponds to a ray along which a line integral of the projection is taken. Then, for that storage location, the length of the portion of the corresponding ray which intersects the pixel is multiplied by the pixel intensity and the contents of the storage location are incremented by the product.