pconvexityselection

Selects regions from convexity degree.

Synopsis

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

Description

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

Convexity is the relative amount that a region differs from a convex region. It is calculated as follows:

convexity = region area / convex hull area.

The maximum value is 1.0 for convex region (eg. circle, square).

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 an real value from [0..1] where 1 is for convex shape.

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 convexity degree ≥ 0.5:

   pconvexityselection 2 0.5 rin.pan rout.pan

C++ prototype

Errc PConvexitySelection( const Reg2d &rg_in, Reg2d &rg_out, int relation, Ushort threshold );

Version française

Sélection de régions sur leur valeur de convexité.

Author: Régis Clouard