Threshold changes when we change contrast value

Support
1

i’m using contrast change in python code,

i.e.

a = slicer.util.arrayFromVolume(self.importedVolume)
self.contrastScale = 2.0
a[:] = a * self.contrastScale

i notice that it changes the threshold value impact on volume in segmentation, how can we relate it with original threshold value input for segmentation.

2

Do not change the voxel values of your volume if you just want to change its display brightness/contrast! Adjust window/level values in the volume’s display node instead.

For example, increase contrast by halving the display window width:

displayNode = self.importedVolume.GetDisplayNode()
displayNode.SetAutoWindowLevelOff()
displayNode.SetWindow(displayNode.GetWindow()/2.0)
3

i’m not using it only to change display brightness , i’m using it cause it helps in body part segmentation.
like it helps to get thin layer of skin etc.

4

You cannot help segmentation by applying linear offset/scaling to voxels. In general, you must not modify the original image.

Complete all segmentation tutorials to learn more about segmentation.