What is picture lock?
Short Answer:
Picture lock is the point in editing where the structure and timing of a video are finalised and agreed — no more scenes added, removed, or reordered. After picture lock, work moves on to finishing: colour grading, sound mixing, graphics, and captions. It is the gate between "changing the story" and "polishing the film".
Overview
Picture lock exists to protect the finishing stages. Colour, sound, and graphics are all built on the locked timeline, so changing the edit afterwards means redoing that finishing work — which is why lock is treated as a firm milestone.
Detailed Explanation
Where picture lock sits in post-production
Assembly and story cut
Client revisions (within the agreed rounds)
Picture lock — structure and timing signed off
Colour grade and sound mix
Online finishing, captions, and graphics
Master files and platform exports
After lock, only grade- and mix-safe tweaks happen without a change order. Adding or reordering scenes late forces the colourist and sound team to redo work, so any structural notes should come before lock, not after.
Example
If a client wants to trim the overall runtime, that is best decided before picture lock — once locked, cutting a section would mean re-grading and re-mixing everything around it, adding time and cost.