BOAC,
Not sure about the Nikon software but the Canon software stores the info about each image in it's own database. This is what it stores:
File Name
Camera Model Name
Shooting Date/Time
Shooting Mode
Tv( Shutter Speed )
Av( Aperture Value )
Metering Mode
Exposure Compensation
Digital Zoom
Image Size
Image Quality
Flash
White Balance
Active AF Points
Parameters
Contrast Normal
Sharpness Normal
Color saturation Normal
File Size
Serial Number
Drive Mode
Owner's Name.
Sadly this all disappears if you lose the database and is not linked if you save the image as another file post-fiddle.
I am assuming (dangerous, I know) that the Nikon system uses a similar system. Check your help file. With a little name swapping you may be able to link the data to a modified file.
MAx