  In this paper a new method of image smoothing for satellite imagery and its
applications in environmental remote sensing are presented. This method is
based on the global gradient minimization over the whole image. With respect to
the image discrete identity, the continuous minimization problem is
discretized. Using the finite difference numerical method of differentiation, a
simple yet efficient 5*5-pixel template is derived. Convolution of the derived
template with the image in different bands results in the discrimination of
various image elements. This method is extremely fast, besides being highly
precise. A case study is presented for the northern Iran, covering parts of the
Caspian Sea. Comparison of the method with the usual Laplacian template reveals
that it is more capable of distinguishing phenomena in the image.
