A readily implementable procedure for improving the lateral resolution of ultrasonic images is proposed. The starting point is the approximation of the sound-beam profile by model functions which arise from the convolution of rectangular functions of varying width. From these model functions it is possible to state analytically the Fourier transforms and their reciprocals. These reciprocals can be allocated to a chain circuit of recursive space frequency filters of the first degree, whereby a single basic element corresponds to the rectangular approximation and still produces a resolution improvement by a factor of 1.5. For noise suppression a low-pass limitation function is introduced whose inverse Fourier transform is mathematically similar to the soundbeam approximation; however, as compared with this, it is compressed by a specific factor and thus is optimally matched to the expected resolution improvement.