Get bias field using sitk

Question

I'm trying to use sitk library to clear biased Mr image (MRI).

I'm able to get the corrected image but can't get the bias image.

Set the following parameters:

shrink_factor=1,
mask_image=mask, 
number_of_iterations=100, 
number_of_fitting_levels=4

This is the code I tried

corrected_image = corrector.Execute(image, maskImage)

log_bias_field = corrector.GetLogBiasFieldAsImage(inputImage)
bias_exp = sitk.Cast(sitk.Exp(log_bias_field), sitk.sitkFloat64)
bias = inputImage / bias_exp
bias = sitk.GetArrayFromImage(bias)
bias = bias / bias.max()

But I get this image:

Do you know how to get the bias only?