9.3. ITK Adaptive Histogram Equalization Image Filter
Power Law Adaptive Histogram Equalization.
Group (Subgroup)
ITKImageStatistics (ImageStatistics)
Description
Histogram equalization modifies the contrast in an image. The AdaptiveHistogramEqualizationImageFilter is a superset of many contrast enhancing filters. By modifying its parameters (alpha, beta, and window), the AdaptiveHistogramEqualizationImageFilter can produce an adaptively equalized histogram or a version of unsharp mask (local mean subtraction). Instead of applying a strict histogram equalization in a window about a pixel, this filter prescribes a mapping function (power law) controlled by the parameters alpha and beta.
The parameter alpha controls how much the filter acts like the classical histogram equalization method (alpha=0) to how much the filter acts like an unsharp mask (alpha=1).
The parameter beta controls how much the filter acts like an unsharp mask (beta=0) to much the filter acts like pass through (beta=1, with alpha=1).
The parameter window controls the size of the region over which local statistics are calculated. The size of the window is controlled by SetRadius the default Radius is 5 in all directions.
By altering alpha, beta and window, a host of equalization and unsharp masking filters is available.
The boundary condition ignores the part of the neighborhood outside the image, and over-weights the valid part of the neighborhood.
For detail description, reference “Adaptive Image Contrast Enhancement using Generalizations of Histogram Equalization.” J.Alex Stark. IEEE Transactions on Image Processing, May 2000.
Input Parameter(s)
Parameter Name |
Parameter Type |
Parameter Notes |
Description |
|---|---|---|---|
Radius |
Vector of UInt32 Values |
Order=X,Y,Z |
Radius Dimensions XYZ |
Alpha |
Scalar Value |
Float32 |
Set/Get the value of alpha. Alpha = 0 produces the adaptive histogram equalization (provided beta=0). Alpha = 1 produces an unsharp mask. Default is 0.3. |
Beta |
Scalar Value |
Float32 |
Set/Get the value of beta. If beta = 1 (and alpha = 1), then the output image matches the input image. As beta approaches 0, the filter behaves as an unsharp mask. Default is 0.3. |
Input Cell Data
Parameter Name |
Parameter Type |
Parameter Notes |
Description |
|---|---|---|---|
Image Geometry |
Geometry Selection |
Image |
Select the Image Geometry Group from the DataStructure. |
Input Cell Data |
Array Selection |
Allowed Types: int8, uint8, int16, uint16, int32, uint32, int64, uint64, float32, float64 |
The image data that will be processed by this filter. |
Output Cell Data
Parameter Name |
Parameter Type |
Parameter Notes |
Description |
|---|---|---|---|
Output Cell Data |
DataObjectName |
The result of the processing will be stored in this Data Array inside the same group as the input data. |
Example Pipelines
License & Copyright
Please see the description file distributed with this plugin.
DREAM3D-NX Help
If you need help, need to file a bug report or want to request a new feature, please head over to the DREAM3DNX-Issues GitHub site where the community of DREAM3D-NX users can help answer your questions.