Images are generated by means of a star test program, considering a set of aberrations using the Zernike polynomials. Additionally, the spot diagram, marginal rays, and the caustic curves of the corresponding images are generated with other programs. A process is applied to the images to generate a processed image, which consists of a set of filters that allows for the extraction of the caustic curves of the last image. It is shown that the caustic curves extracted from the processed image and the caustic curves simulated are practically the same. Results obtained with experimental images are shown too.