Adjust window width and level with Transforms

[pauljhin]

Hello,

I would like to adjust the brightness and contrast of my CT images to the bone standard (W: 2000 L: 400). I tried using the ScaleIntensityRange but it doesn't seem to be working with the values. Is there any function that I can do this?

Is there also some function that just normalizes the values between 0 and 1?

Thanks in advance

[KumoLiu]

Hi @pauljhin, you can use ScaleIntensity. It can scale the intensity of input image to the given value range (minv, maxv).
https://github.com/Project-MONAI/MONAI/blob/89684d677f6c93c6fbd023a614c07485c5223557/monai/transforms/intensity/array.py#L408
Hope it can help you, thanks!

[pauljhin]

Hi @KumoLiu ,

Thank's for your reply! The part of scale (or normalize) the values from 0 to 1 worked.

But I would like to know how to change brightness and contrast (window and level) like this article. This is not worked.

[KumoLiu]

Hi @pauljhin, if you want to change the window level and window width. You can do this:

tutorials/deployment/Triton/models/monai_covid/1/model.py

Line 100 in f43e771

ScaleIntensityRange(a_min=-1000, a_max=500, b_min=0.0, b_max=1.0, clip=True),

a_min and a_max are the upper and lower bounds of window width.
Thanks!

[pauljhin]

Thanks!

[hreso110100]

@KumoLiu so for example if for abdomen W is 350 and L is 40 then what are values of a_min and a_max ? Thanks

[KumoLiu]

Hi @hreso110100, you can calculate it by using:

• max - min = W
• (max + min) / 2 = 40

Thanks!