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ll_edges

$ \bigcirc$Name


ll_edges Extract maximal meaningful edges (contrasted pieces of level lines) from a Fimage




$ \bigcirc$Command Synopsis


ll_edges [-e eps] [-s step] [-p p] [-t tree] [-z] in out



-e eps : -log10(max. number of false alarms), default 0

-s step : quantization step (bilinear), default 1.

-p p : sampling precision (bilinear), default 2

-t tree : use a precomputed FLST tree

-z : use zero order instead of bilinear interpolation

in : input Fimage

out : output edges (Flists)




$ \bigcirc$Function Summary


Flists ll_edges (in , tree , eps , step , precision , z )

Fimage in ;

Shapes tree ;

float *eps , *step ;

int *precision ;

char *z ;




$ \bigcirc$Description


This modules computes all the level lines of an image (with the same options -s, -p, -z and -t as the ll_extract module) and keeps the most contrasted parts of them. The detection is made using a thresholding function balancing between the minimum contrast (gradient norm) along each part and the corresponding length of the curve. This function ensures that at most 10-eps false detections could occur by chance with independent random gradient values (see [DMM01]).


Notice that contrary to the ll_boundaries detection, this module can detect non-closed level lines, since each subpart of each level line is considered.


The result is a collection of curves stored in a Flists structure.




$ \bigcirc$See Also


fderiv, fhisto, flst, flstb_boundary, flst_bilinear, flst_boundary, flstb_quantize, fsaddles, sintegral.




$ \bigcirc$Version 1.0


Last Modification date : Thu Nov 29 20:23:56 2001


$ \bigcirc$Author


Lionel Moisan






next up previous contents index
Next: vpoint Up: Reference Previous: ll_boundaries   Contents   Index
mw 2004-05-05