The
old and important drawings as well as documents which have stood
the test of time and degenerated can be restructured. The old
documents/drawings are scanned and all the unwanted spots and
other marks are cleaned using the various raster modification
software.

This basically
refers to edge matching with adjacent drawings, quality checking,
replacing the missing elements, merging etc.

Image
editing refers to the removal of unwanted parts in the maps/drawings,
e.g. removing images of furniture from the elevation drawing
of a building.