Phansalkar
The Phansalkar filter, based on the work of Sauvola and Pietikäinen, 2000, deals with low-contrast images. For more information about the theory, see Phansalkar et al., 2011.
The Sphere Radius setting controls the radius of the mask used for the mean filter.
The local threshold T is determined by the mean m and standard deviation s of the pixel intensities:
p defines the strictness of noise removal in low-contrast, dark regions, and q specifies those regions.
K defines the strictness of noise removal in low-contrast bright regions. It takes values between 0.2 and 0.5.
R specifies the noise regions and has a value range of 0.2 to 0.8. It is the dynamic range of the standard deviation and is equal to 0.5 for a normalized image.
The local mean and standard deviation adjust the local threshold value.
|
Know how! You can Save your current settings for this tool as Start-Up Settings . The next time you process an image, these settings will be automatically loaded and filled into the parameter fields. You can also load the Built-In Default Settings available in GeoDict. If you change any settings and want to revert to your saved start-up settings, click the corresponding button to Load the Start-Up Settings . |
Click Create Segmentation to use the Phansalkar method to segment the gray value image. This thresholding method does not generate a GeoDict result file. The resulting structure is displayed in the GeoDict visualization area. The gray value image remains in memory and can be compared to the structure. In the visualization panel above the visualization area, check Structure and uncheck Volume Field to only visualize the structure. To save the structure as a *.gdt file, select File → Save Structure as from the menu bar in the main GeoDict GUI.
