See if the function imregionalmax() will do what you want. It finds local maxima and gives you a binary image indicating their location.
BW = imregionalmax(I) returns the binary image BW that identifies the regional maxima in I. Regional maxima are connected components of pixels with a constant intensity value, and whose external boundary pixels all have a lower value. In BW, pixels that are set to 1 identify regional maxima; all other pixels are set to 0. By default, imregionalmax uses 8-connected neighborhoods for 2-D images and 26-connected neighborhoods for 3-D images. For higher dimensions, imregionalmax uses conndef(ndims(I)),'maximal').
