Use your character in Grok Imagine
Grok Imagine animates a still as the first frame and, on the 1.5 model, also accepts a stack of reference images so the same face, outfit and proportions carry across clips that do not start from the sheet. It is the most flexible of the five for a multi-view pack: pin hero.png as the first frame and hand it the other views as references in the same request.
Capabilities
- First frame (image-to-video)Yes
- Last frameYes
- Reference images7
- Native extendYes
- Max clip15 s at 480p, 720p or 1080p (reference-to-video is capped at 720p)
- AudioYes
Which files to use
hero.pngFirst frame (image-to-video). Output keeps the 2:3 aspect of the still.closeup.pngReference image slot 1 (reference-to-video). Best single image for face identity.three_quarter.pngReference image slot 2. Gives the model the face at an angle.profile.pngReference image slot 3. Side silhouette, hair and jawline.back.pngReference image slot 4. Needed only if the action turns the character around.contact_sheet.pngOptional single reference when you only have one slot: all five views in one 16:9 image.character.jsonCopy the bible text into every prompt; the seed does not transfer to video.
Steps
- Open grok.com or the Grok app and switch to the Imagine tab (a paid Grok plan is required for video).
- Click the image upload control in the composer and add hero.png. The still becomes the first frame and the clip keeps its 2:3 aspect ratio.
- If your plan exposes reference images, add closeup.png, three_quarter.png and profile.png as references in the same request so the identity holds when the camera moves off the first frame.
- Paste the bible text from character.json, then describe the motion, not the picture: what the character does, where the camera goes, what is said.
- Pick duration, resolution and aspect ratio. For a first pass use 720p and a short duration; 1080p is only available for text-to-video and image-to-video, not reference-to-video.
- Generate, review for identity drift (eyes, hairline, outfit colours), and regenerate with a stronger bible line for whatever drifted.
- To continue the scene, use the extend feature on the finished clip with a continuation prompt instead of starting a fresh image-to-video job.
Prompt template
{{bible}} The first frame shows this exact character; keep the face, hair, skin tone, outfit and proportions unchanged throughout. {{action}} Natural motion, steady camera, cinematic lighting, no new characters. If reference images are attached: the character in <IMAGE_1> and <IMAGE_2> is the same person as in the first frame.
Tips
- Keep the full bible text at the top of every prompt, including extensions. The model only knows what it can see in the frame and what you tell it.
- closeup.png is the strongest identity anchor. If you can only attach one reference, use it rather than the full-body hero.
- Describe what moves, not what is in the picture. Re-describing the still fights the first frame and causes drift.
- For a scene that ends in a known pose, supply that view (for example three_quarter.png) as the last frame on grok-imagine-video-1.5 and let the model interpolate.
- Chain long scenes with the extension endpoint rather than regenerating from a frame grab; extension picks up from the last frame of the input clip.
- Image-to-video ignores the aspect ratio setting and follows the still. Crop hero.png yourself if you need 16:9.
Caveats
- xAI pages disagree on the reference image cap: the video overview says up to 14 reference images and 3 voice references on grok-imagine-video-1.5, while the reference-to-video page and third-party API mirrors say 7. We list 7 as the safe number.
- The overview says that on 1.5 an image combined with reference images, reference audio or a last frame is treated as reference-to-video with a pinned first frame. On the older grok-imagine-video model the two modes are separate: a single first-frame image or references, not both.
- Video extension is a separate endpoint (/v1/videos/extensions) documented for the grok-imagine-video model; the capability table marks extension as not available on the 1.5 models at the time of writing.
- First-and-last-frame support is described in the 1.5 text but the capability table row is blank. Treat last-frame pinning as preview behaviour and test it.
- Consumer app limits (duration tiers, resolution, whether reference slots appear) depend on the subscription plan and change frequently; the API limits above are the documented ones.
- The exact request field for a last frame could not be confirmed from the REST reference; the overview text names it last_frame but check the live schema.
API notes
POST https://api.x.ai/v1/videos/generations with model grok-imagine-video or grok-imagine-video-1.5, a prompt, an image object (url, base64 data URI, or a Files API file_id) for the first frame, and optionally a reference_images array of url objects; refer to references in the prompt as <IMAGE_1>, <IMAGE_2> and so on. The call is asynchronous and returns a request_id that you poll until the video URL is ready; the official xAI SDKs can poll for you. Extension is a separate POST to /v1/videos/extensions that takes the finished video and a 2 to 10 second continuation.