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ll_remove

$ \bigcirc$Name


ll_remove Remove small level lines in a mimage




$ \bigcirc$Command Synopsis


ll_remove [-l L] input output



-l L : Minimal level lines length

input : Original mimage

output : Output mimage with missing level lines




$ \bigcirc$Function Summary


Mimage ll_remove (mimage , L )

Mimage mimage ;

int *L ;




$ \bigcirc$Description


This module copies the level lines recorded in the input mimage to the output mimage, but the ones with length (number of pixels) less than a given threshold. The length threshold (10 by default) can be changed using the option -l.

The morpho line first_ml field of the input mimage must contain a chain of level lines only that is, the boundaries of the connex components of the level sets Ki = {(x, y) / g(x, y) $ \geq$ vi}, for i = 1,..., N. or of the level sets Li = {(x, y) / g(x, y) $ \leq$ vi}, g being the gray levels image, N the number of gray levels in g and (vi)i the sequence of gray levels sorted in increasing order. Such mimage can be computed from a bit-mapped image using the module ll_decompose.

The operation of removing the smallest level lines can be interpreted, because of the level lines inclusion principle, as a thresholding of extrema gray levels values in small areas. When the input mimage contains level lines associated to Ki, the extrema gray levels are maxima; when the level lines are associated to Li, they are minima.

You may get some applications of this filter in [Fro00] and [Fro99]. It is a good example of a very simple use of the modules ml_decompose and ml_reconstruct. However, since the Fast Level Sets Transform [MG00] (flst) has been implemented, you would get faster computation by using flst-based modules (such as fgrain, which considers the area instead of the length).




$ \bigcirc$See Also


llremove.


$ \bigcirc$Version 1.1


Last Modification date : Thu Jan 24 18:41:08 2002


$ \bigcirc$Author


Jacques Froment






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Next: llremove Up: Reference Previous: llmap   Contents   Index
mw 2004-05-05