I don’t know if you corrected this problem. But I corrected this using gimp by setting the image > mode > grayscale
Image > precision > 16 bit perceptual gamma
and export png with 16bpc GRAY
Hope this helps
I don’t know if you corrected this problem. But I corrected this using gimp by setting the image > mode > grayscale
Image > precision > 16 bit perceptual gamma
and export png with 16bpc GRAY
Hope this helps