Interpolated cropping slicghtly changes voxel values

[manjula (Manjula Herath)]

I am getting very minor difference in voxel values when I crop with the ROI box. I used the crop volume with Linear interpolator and isotropic spacing and default settings.

When I calculate the mean value in segment statistics with the Scalar volume select as the Crop volume and then with the original volume using the same segment, the mean value is slightly different. The size remains the same.

Is it because of the Cropping algorithm and is this to be expected ? or am i doing something wrong?

It does not affect my calculations and seems very very trivial but I am just curious why this happens.

[lassoan (Andras Lasso)]

It is expected that if origin, spacing, or axis directions of the output volume are not exactly the same as the input volume’s then interpolated values in the output volume will not be exactly the same. However, the difference should be negligible.