# What Optic does > Optic revises a video you already have. It changes only what you name — a subject, what it wears, on-screen text, the look — and keeps the rest. Optic is ROUTIX's own tool for revising a video you already have. You choose a stretch of your clip, say what should change, and Optic makes a new film of that stretch in which **only what you named is different**. Its words box says it plainly: *"Say what should change. Everything you don't name stays as it is."* ## What Optic can change Optic works on any kind of footage — people, animals, objects, places, animation, screen recordings. What it changes is up to your words: - **A subject, replaced or transformed.** Turn one person into another, a dog into a fox, a car into a different car. Add your own pictures to show exactly what it should become — see [Your picture is what you want](#your-picture-is-what-you-want). - **Something that belongs to a subject.** What someone wears, layer by layer; their hair or make-up; a mark, a tattoo; what they hold; a companion; their state (wet, muddy, glowing). It can apply to the whole stretch or only to some of its seconds. - **Text on the screen.** Change a caption, a sign or lettering, or remove it. - **The look of the video.** Light, colour and style — or what is seen in the picture. You can ask for several changes at once, each in its own sentence; Optic makes them all in the same film. ## Your picture is what you want When you add a picture of what a subject should become, that picture is the new look — whole. **Everything it shows of the subject comes into your video**: the face, the hair, what it wears, what it holds, even a tail. So choose the picture that shows the subject exactly as you want it seen. - **Something in the picture you do not want seen?** Give a picture without it, or say so in your words — *"…the person in @Image 1, without the cap"*. - **What the picture does not show stays as your video has it.** A close picture of a face brings the face; the clothes it does not show stay as they are in your video. - **Only the subject comes in.** The picture's background, its light and the pose it was taken in stay out: the place, the light and every movement are your video's. ## What stays as it was - **Everything you do not mention stays as your video has it** — the place and every object in it, the camera (every move, stop and framing), the light, the shadows and the colour, the focus and the blur, every movement and every event, and the timing of each moment. - **The performance is your video's.** The new subject's eyes, gaze, lips and every expression follow the original, frame for frame, at the same moments — whether or not anyone speaks. - **Whatever happens to the old subject happens to the new one,** at the same moments and only where your video shows it — a mark that appears, damage, blood, a glow. - **Only what your change touches is new.** Shots your change does not reach — an insert, an effect or a graphic, black between shots, a shot the subject is not in — come back as your video's own frames. Every cut stays where your video has it, and a fade stays a fade. - **The sound.** Your film keeps the clip's own sound, in time with every frame. - **The shape.** The film has your clip's shape (wide, tall or square). ## What Optic does not do - **A change to what happens in the shot.** Optic keeps the story; a request that changes the action itself is not a revision, and Optic says so: *"This changes what happens in the shot, so it is made anew rather than revised."* — and your credits come back. To change the story, use the chat: it makes those moments anew, around what happens now. See [Making video in the chat](https://routix.studio/help/chat/making-video-in-the-chat). - **The camera alone or the sound alone.** A request only about framing, camera movement or sound is not something Optic makes on its own. ## When your words could mean two things If your words could mean two subjects equally — "the man" when there are two men — Optic does not pick one behind your back. Before you press **Revise**, mark the one you mean with [Focus](https://routix.studio/help/focus/what-is-focus), or say which one in words — *"the man on the left in the grey coat"*. If Optic still cannot tell, it makes nothing and your credits come back. ## What you get A new film of the stretch you chose, in 720p or 1080p — 720p unless you choose otherwise before you press. **Revise** is the one press: the price on its button is what is held, and the reading of your clip and the making of your film follow inside that run. A film is delivered whole, or it is not delivered and every credit comes back. When you bring in a new character, it stays the same through the whole film, looking exactly as your picture shows it. See [Revise a video step by step](https://routix.studio/help/optic/revise-a-video). ## Optic in numbers - **Up to 60 seconds** of your clip in one revision, delivered as one film. (The timeline always holds the exact limit.) - **Up to 500 focuses** on one clip, each pointing at exactly the subject or place you mean — see [Focus](https://routix.studio/help/focus/what-is-focus). - **Up to 9 of your own pictures** in one revision, to show what something should become. So one revision can point at up to 500 things to change, and show up to 9 pictures of what they should become. ## Built on ROUTIX Blind Before Optic changes anything, it reads the whole stretch you chose — every cut, what happens and when, who and what is there in every shot, the words on screen, and — for whatever you ask to change — what it wears and holds, moment by moment — so a person keeps one identity through every shot, and only what you name changes. That reading is [ROUTIX Blind](https://routix.studio/help/why-routix/routix-blind), ROUTIX's own perception and reasoning core, at work — inside every revision, before anything is made. Source: https://routix.studio/help/optic/what-optic-does · Updated 2026-10-24