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tjpoint

$ \bigcirc$Name


tjpoint Return the type of junction of a point in a cimage




$ \bigcirc$Command Synopsis


tjpoint [-c] [-a tarea] [-q tquant] [-l lambda] [-m mu] [-x xlambda] [-y ylambda] [-X xmu] [-Y ymu] U x0 y0 .



-c : 8-connexity (default : 4)

-a tarea : area threshold

-q tquant : quantization threshold

-l lambda (screen output) : returns lambda such that {x / U(x) <  = lambda} is significant at the junction

-m mu (screen output) : returns mu such that {x / U(x) >  = mu} is significant at the junction

-x xlambda (screen output) : returns the T-junction point xlambda belonging to the border of {x / U(x) <  = lambda}

-y ylambda (screen output) : returns the T-junction point ylambda belonging to the border of {x / U(x) <  = lambda}

-X xmu (screen output) : returns the T-junction point xmu belonging to the border of {x / U(x) >  = mu}

-Y ymu (screen output) : returns the T-junction point ymu belonging to the border of {x / U(x) >  = mu}

U : input cimage U

x0 : x coordinate of the point

y0 : y coordinate of the point

. (screen output) : type of junction at (x0,y0)




$ \bigcirc$Function Summary


int tjpoint (connex8 , tarea , tquant , U , x0 , y0 , lambda , mu , xlambda , ylambda , xmu , ymu , M , P )

char *connex8 ;

int *tarea ;

int *tquant ;

Cimage U ;

int x0 , y0 ;

int *lambda , *mu , *xlambda , *ylambda , *xmu , *ymu ;

unsigned char *M ;

int *P ;




$ \bigcirc$Description


This module returns the type of junction of the given point (x0, y0) of the input cimage U. It returns 0 if this point is not a junction, 1 if it is a T-junction and 2 if it is a X-junction. For a description of the junction detection algorithm, please see [CCM96],[CCM99] and [Fro99].

The option -a allows to choose the area threshold associated to the detection, while the option -q is related to the quantization threshold. Those thresholds are used to avoid false detections.

The options -l and -m allow to get the $ \lambda_{1}^{}$ and $ \mu_{1}^{}$ values computed by the algorithm, when (x0, y0) is a junction. The borders of the two significant level sets L$\scriptstyle \lambda_{1}$ = $ \left\{\vphantom{(x,y) /U(x,y) \leq \lambda_1 }\right.$(x, y)/U(x, y) $ \leq$ $ \lambda_{1}^{}$$ \left.\vphantom{(x,y) /U(x,y) \leq \lambda_1 }\right\}$ and M$\scriptstyle \mu_{1}$ = $ \left\{\vphantom{(x,y) /U(x,y) \geq \mu_1 }\right.$(x, y)/U(x, y) $ \geq$ $ \mu_{1}^{}$$ \left.\vphantom{(x,y) /U(x,y) \geq \mu_1 }\right\}$ are going through the junction.

The options -x, -y, -X and -Y allow to get the points (x$\scriptstyle \lambda_{1}$, y$\scriptstyle \lambda_{1}$) and (x$\scriptstyle \mu_{1}$, y$\scriptstyle \mu_{1}$) of the four neighbour points of the junction, so that (x$\scriptstyle \lambda_{1}$, y$\scriptstyle \lambda_{1}$) belongs to the border of L$\scriptstyle \lambda_{1}$ and (x$\scriptstyle \mu_{1}$, y$\scriptstyle \mu_{1}$) to M$\scriptstyle \mu_{1}$.




$ \bigcirc$See Also


tjmap.


$ \bigcirc$Version 1.1


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


$ \bigcirc$Author


Vicent Caselles, Bartomeu Coll, Jacques Froment, JL Lisani






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