In mathematical morphology, the h-maxima transform is a morphological operation used to filter local maxima of an image based on local contrast information. First, all local maxima are defined as connected pixels in a given neighborhood with intensity level greater than pixels outside the neighborhood. Second, all local maxima that have height f {\displaystyle f} lower or equal to a given threshold are suppressed. The height f of the remaining maxima is decreased by h {\displaystyle h} .
The h-maxima transform is defined as the reconstruction by dilation of f {\displaystyle f} from f − h {\displaystyle f-h} :
HMAX h ( f ) = R f δ ( f − h ) {\displaystyle \operatorname {HMAX} _{h}(f)=R_{f}^{\delta }(f-h)}- Soille, P., "Morphological Image Analysis: Principles and Applications" (Chapter 6), 2nd edition (2003), ISBN 3540429883.