Original images are the raw unprocessed DICOMS. All pre- and post-processed images are derived from original DICOM images.

Pre-processed images (depending on scanner) have undergone a combination of the corrections outlined at the following link: http://adni.loni.usc.edu/methods/mri-analysis/mri-pre-processing/

Post-processed scans have undergone various other corrections.

To see the precise processing steps performed on pre-or post- processed scans, select an image description once you have performed a search. You will be directed to a page with information on the exact processing steps for that image.