Finished positive print from original negative — intermediary for creating additional negatives or lab prints without touching the source.
In the classic photo-chemical film business, the interpositive was the bulwark between the original and mass production. After color correction and final color timing of the original negative, you had a finished positive copy – and under no circumstances would you put that directly into the printing machine. The original negative stays in the safe. The IP is the secure intermediate layer.
How does the workflow function? After all DCP decisions are finalized, you expose a high-resolution interpositive from the original film. This is then no longer touched – it lives in the climate-controlled vault. From this IP, you then create duplicate negatives, which go to the labs in all countries. Should a dupe negative be damaged or a new batch of prints need to be made, you don't need to access the original. The interpositive is your insurance policy.
In practice, this also meant: the IP could be archived without wearing out the original negative. You could pull countless duplicate negatives from an IP and wouldn't lose generational quality like with the old dupe-negative-from-dupe-negative process. Modern DI workflows have made this physical necessity obsolete – today, everything runs digitally, and a DCP is your "interpositive" equivalent: the secure, immutable reference file from which all distribution materials originate.
The term itself is less present today, but anyone working with classic film archives or needing to master 16mm documentaries will still regularly encounter IP processes. It also conceptually shows why digital mastering standards today demand such strict versioning – the interpositive concept lives on in backup protocols. Generation protection instead of generational loss.