Applies a 2D Wiener filter on a 3D input array, slice by slice. More...
#include "stir/WienerArrayFilter2D.h"
Public Member Functions | |
| bool | is_trivial () const override |
| Should return true when the operations won't modify the object at all. More... | |
 Public Member Functions inherited from stir::ArrayFunctionObject_2ArgumentImplementation< 3, elemT > | |
| void | operator() (Array< num_dimensions, elemT > &array) const override |
| in-place modification of array, implemented inline | |
| void | operator() (Array< num_dimensions, elemT > &out_array, const Array< num_dimensions, elemT > &in_array) const override |
| result stored in another array More... | |
| Public Member Functions inherited from stir::ArrayFunctionObject< num_dimensions, elemT > | |
| virtual Succeeded | get_influencing_indices (IndexRange< num_dimensions > &influencing_indices, const IndexRange< num_dimensions > &output_indices) const |
| sets the range of indices that influences the result in a set of coordinates output_indices More... | |
| virtual Succeeded | get_influenced_indices (IndexRange< num_dimensions > &influenced_indices, const IndexRange< num_dimensions > &input_indices) const |
| sets the range of indices that gets influenced by a set of coordinate input_indices More... | |
Additional Inherited Members | |
| Protected Member Functions inherited from stir::ArrayFunctionObject_2ArgumentImplementation< 3, elemT > | |
| virtual void | do_it (Array< num_dimensions, elemT > &out_array, const Array< num_dimensions, elemT > &in_array) const=0 |
Detailed Description
template<typename elemT>
class stir::WienerArrayFilter2D< elemT >
Applies a 2D Wiener filter on a 3D input array, slice by slice.
This function applies a Wiener filter on each 2D slice of a 3D volume independently, using a fixed 3x3 window. For each pixel in the slice, the filter estimates the local mean and variance, and uses these values, along with the noise variance estimated from the entire slice, to reduce noise while preserving details. The filtered output is stored in the out_array.
The formula used for the Wiener filter is:
![\[ \text{output}(i, j) = \left(\frac{\text{input}(i, j) - \text{localMean}(i, j)}{\max(\text{localVar}(i, j), \text{noise})}\right) \cdot \max(\text{localVar}(i, j) - \text{noise}, 0) + \text{localMean}(i, j) \]](form_160.png)
localMean[i][j]is the mean of the 3x3 neighborhood around pixel(i, j).localVar[i][j]is the variance of the 3x3 neighborhood around pixel(i, j).noiseis the average noise variance estimated over the entire slice.
- Warning
- The edges of each 2D slice are not processed, as the filter does not have sufficient neighboring pixels for the 3x3 window.
Wiener Filter Configuration
This filter is fully automated and does not require any parameters. To enable it in the reconstruction process, include the following in the parameter file:
- Note
- This filter operates on each axial slice independently, and does not take into account neighboring slices. It is effectively a 2D filter applied slice-by-slice on a 3D volume.
Member Function Documentation
◆ is_trivial()
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overridevirtual |
Should return true when the operations won't modify the object at all.
For the 2 argument version, elements in out_array will be set to corresponding elements in in_array. Elements in out_array that do not occur in in_array will be set to 0.
Implements stir::ArrayFunctionObject< num_dimensions, elemT >.
The documentation for this class was generated from the following files:
- /home/sirfuser/devel/STIRdistrib/STIR/src/include/stir/WienerArrayFilter2D.h
- /home/sirfuser/devel/STIRdistrib/STIR/src/buildblock/WienerArrayFilter2D.cxx
