peccentricityselection

Selects regions from eccentricity degree.

Synopsis

peccentricityselection relation threshold [-m mask] [rg_in|-] [rg_out|-]

Description

peccentricityselection selects regions from their eccentricity degree. The parameter relation specifies the order relation to the threshold value that is used to select or not a region.

Eccentricity measures how much the region deviates from being circular. It is defined as the ratio of the length of the short axis to the length of the long axis:

              (Mxx+Myy-sqrt( (Mxx-Myy)*(Mxx-Myy)+4*Mxy*Mxy))
eccentricity= ----------------------------------------------
              (Mxx+Myy+sqrt( (Mxx-Myy)*(Mxx-Myy)+4*Mxy*Mxy))

The maximum value is 1.0 for a square or a circle.

Parameters

relation is an integer from [-3,3] which specifies the order relation to the threshold value:
- relation = 3: regions with the maximum value.
- relation = 2: regions >= threshold.
- relation = 1: regions > threshold.
- relation = 0: regions = threshold.
- relation = -1: regions < threshold.
- relation = -2: regions <= threshold.
- relation = -3: regions with the minimum value.
threshold is a real value from [0..1].

Inputs

rg_in: a 2D region map.

Outputs

rg_out: a 2D region map.

Result

Returns the number of selected regions.

Examples

Selects regions with the highest eccentricity degree:

   peccentricity 3 0 rin.pan rout.pan

C++ prototype

Errc PEccentricitySelection( const Reg2d &rg_in, Reg2d &rg_out, int relation, Ulong threshold );

Version française

Sélection de régions sur leur valeur d'exentricité.

Author: Régis Clouard