Fast implementation of large erosions and dilations in Mamba

Large structuring elements are used in many morphological transformations. They are needed when computing size distributions, in filtering operators (and especially in alternate sequential filters), for regularised gradients and large top-hat transforms, for residual operators (skeletons by openings, critical balls, ultimate openings and so on). Moreover, in some applications, images are large and even very large. Remind that Mamba is able to process images containing up to 16.10 pixels, value which corresponds for instance to a 4096x4096 pixels image. So, it is not unusual, when dealing with these images, to need very large erosions, dilations, openings or closings. Performing an ultimate opening on such an image may require the use of opening sizes up to 2000!