What are originals?
Originals are the original digital RAW, GIF, JPEG, TIFF, DNG, PNG, audio, or video files that are imported into Aperture from digital cameras, memory cards, computers, CDs, DVDs, or storage devices such as external hard disk drives. Aperture never changes the original, so you always have originals to work from.
Important: Originals—especially RAW files—tend to be quite large. Projects consisting of several thousand originals require high-capacity hard disks.
For information about importing originals, see Importing photos overview.