Picture lock

The declaration that the image will no longer change: cut frozen so sound, music and grade can build on solid ground.

Picture lock is the edit's constitutional moment: from here, sound design times its events to frames that will not move, the composer scores to fixed durations, the colourist grades shots that will not vanish. Every downstream craft builds on the lock; that is why it exists.

Breaking lock is the industry's most expensive small decision: one trimmed shot ripples through mix, score and grade as redone work. Hence the ceremony around declaring it, screenings, sign-offs, the long pause before the word. Lock is also psychological mercy: the film stops being infinitely revisable, and everyone is finally working on the same film.