An original file would be the same file byte for byte in the original obsolete image format for example ILBM/IFF. An exact copy would be a lossless PNG (for ex

An original file would be the same file byte for byte in the original obsolete image format for example ILBM/IFF. An exact copy would be a lossless PNG (for example) of the image, that you wouldn't be able to tell the difference by looking at it when it's displayed on a screen from the original.