I am trying to convert dicom CT images of brain to nii but the result of the conversion is a plain brain images where the details of the images (such as ventricles and grey matters) are all grayed out/hidden. I have attached a screenshot of a slice of the original DICOM image and the converted nii image.

But, when I adjust the window/level value of the converted nii image the details of the image are visible again. I think the conversion is not considering window width and window center value present in DICOM tags of the original dcm images.

How can I include the window width and window center for the conversion?

Thanks!