pvariancevalue

Synopsis

Description

pvariancevalue measures the global variance of the input grayscale image or graph im_in.

The variance is calculated as follows:

   variance = MOMENT_2 - (MEAN * MEAN);

For image, the variance is measured from the pixel values.

For graph, the variance is measured from the node values.

The variance values for each band are stored in the collection col_out.

Notice : This operator is not maskable.

Inputs

• im_in: a grayscale image or a graph.

Outputs

• col_out: a collection of float values.

Result

Returns the global variance value (for the first band only). This value can be get using operator pstatus.

Examples

Measures the global variance of the tangram.pan (Unix version):

   pvariancevalue tangram.pan col.pan
   val=`pstatus`
   echo "Variance = $val"

Measures the global variance of the tangram.pan (MsDos version):

   pvariancevalue tangram.pan col.pan
   call pstatus
   call pset val
   echo Variance = %val%

See also

C++ Prototype

Version française

Calcul de la valeur variance des pixels d'une image (d'un graphe ou d'une carte de régions).