pareaselection

Selects regions from area size.

Synopsis

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

Description

pareaselection selects regions from their area size. The parameter relation specifies the order relation to the threshold value that is used to select or not a region.

The area is calculated from the number of pixels included in the region and on the boundary. The algorithm uses one half pixel for concavity. For example, the area is 10 pixels for the following region (8 + 4*0.5) :

    xx
   xxxx
    xx

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 integer defined in pixel unit.

Inputs

rg_in: a 2D region map.

Outputs

rg_out: a 2D region map.

Result

Returns the number of selected regions.

Examples

Selects all regions with area size = 50 pixels:

   pareaselection 0 50  rin.pan rout.pan

C++ prototype

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

Version française

Sélection de régions sur leur valeur de surface.

Author: Régis Clouard