Up: Smoothing Tasks
Smoothes an image using the Conjugate Gradient Algorithm.
(Author: Didier GIRARD, Groupe d'Astrophysique)
The smoothed image is the equilibrium state of a thin flexible
plate constrained to pass near each height datum by a spring attached
between it and the plate. The smoothing is controled by the "Smoothing
Parameter" P :
P = ( plate stiffness) / ( springs stiffness)
A low value for P (0.001) means high fidelity to the original data and
should be used for high signal to noise ratios. If the data are noisy,
use higher values of P (0.1 to 10). The algorithm is iterative and
needs a work space equal to 3 input maps. It usually converges in 10
iterations, and can be restarted if you save the work files. Timing is
of the order of 2 seconds of microVAX II CPU time for a 128 by 128 map.
It takes into account blanked pixels properly.