DWI to ADC

Hi,
I’m trying to get adc maps from dwi NIFTI files. But I think I’m not writing the command in the right way.

I use:

dwi2adc -fslgrad bvecs bvals output.nii.gz

Could you please help me.

Thanks

The input data is missing. You need dwi2adc -fslgrad bvecs bvals input.nii.gz output.nii.gz

Thank you very much!