Generalised Kuwahara filter
#include "dip_filtering.h"
dip_Error dip_GeneralisedKuwaharaImproved ( in, selection, out, se, boundary, param, shape, threshold, minimum )
binary, integer, float
This function implements an improved version of GeneralisedKuwahara, see that function's description for more information. This function adds a threshold parameter that avoids false edges in uniform regions. If the difference between maximal and minimal values within the filter window is smaller or equal to threshold, the centre pixel is taken, instead of the minimum (or maximum). Setting threshold to zero yields the same result as GeneralisedKuwahara.
Only the rectangular, elliptic and diamond filter shapes are supported (DIP_FLT_SHAPE_RECTANGULAR, DIP_FLT_SHAPE_ELLIPTIC and DIP_FLT_SHAPE_DIAMOND). Other filter shapes can be implemented by setting shape to DIP_FLT_SHAPE_STRUCTURING_ELEMENT, and passing a binary image in se. The "on" pixels define the shape of the filter window. Other values of shape are illegal.
If shape is not equal to DIP_FLT_SHAPE_STRUCTURING_ELEMENT, se can be set to zero. When shape is set to DIP_FLT_SHAPE_STRUCTURING_ELEMENT, param is ignored, and can be set to zero.
| Data type | Name | Description |
| dip_Image | in | Input |
| dip_Image | selection | Selection |
| dip_Image | out | Output |
| dip_Image | se | Custom filter window (binary) |
| dip_BoundaryArray | boundary | Boundary conditions |
| dip_FloatArray | param | Filter sizes |
| dip_FilterShape | shape | Filter shape |
| dip_float | threshold | Minimal value difference within window |
| dip_Boolean | minimum | Select minimum or maximum? |
The enumerator dip_FilterShape contains the following constants:
| Name | Description |
| DIP_FLT_SHAPE_DEFAULT | Default filter window, same as DIP_FLT_SHAPE_RECTANGULAR |
| DIP_FLT_SHAPE_RECTANGULAR | Rectangular filter window, can be even in size |
| DIP_FLT_SHAPE_ELLIPTIC | Elliptic filter window, always odd in size |
| DIP_FLT_SHAPE_DIAMOND | Diamond-shaped filter window, always odd in size |
| DIP_FLT_SHAPE_PARABOLIC | Parabolic filter window (morphology only) |
| DIP_FLT_SHAPE_DISCRETE_LINE | Rotated line structuring element (morphology only) |
| DIP_FLT_SHAPE_INTERPOLATED_LINE | Rotated line structuring element, through interpolation (morphology only) |
| DIP_FLT_SHAPE_PERIODIC_LINE | (not implemented) |
| DIP_FLT_SHAPE_STRUCTURING_ELEMENT | Use se as filter window, can be any size |
Kuwahara, GeneralisedKuwahara, KuwaharaImproved, VarianceFilter, Uniform