You always see the real image. The coordinates (both the anatomical/patient coordinates and voxel coordinates) are also all real and correct. You may turn off interpolation (Volumes module / Display / Interpolate checkbox) if you want to make sure that at a certain position in the image you see the contribution of exactly one pixel of the image slices.
If you could tell what your application (anatomy, procedure, imaging modality, etc) and your concerns are then we could give more specific answer.