ScaleIntensityRanged - Parameters

[agokli]

I like to understand defining parameters for ScaleIntensityRanged:

(a) a_min (float) – intensity original range min
(b) a_max (float) – intensity original range max.

Question - How do I define a_min and a_max for all of images?
Question - How do they relate to Window and Level?
Question - I am using 3D Slicer to get Window and Level. How do I use these to define a_min and a_max?

spleen_segmentation_3d example has above parameters set to:
a_min =-57
a_max=164

Need to understand how they are defined.

[KumoLiu]

Hi @agokli, thanks for your interest here.

In ScaleIntensityRanged, the parameters a_min and a_max represent the minimum and maximum values of the intensity range that the original image intensities will be mapped from. This is a linear rescaling of the pixel intensity values from the original range [a_min, a_max] to a new range, often [0, 1] or [0, 255] depending on the application.
You can use DataAnalyzer to automatically analyzes given medical image dataset and reports the statistics.
For the relationship between WW, WL and intensity range, you can refer to:https://radiopaedia.org/articles/windowing-ct

Thanks.