H3 Max Relight is a dedicated video relighting tool announced by fal on October 7, 2026. Its purpose is to change illumination in an existing shot while retaining the subjects, movement, camera behavior, and audio. Those retention goals are provider claims, not results from our own tests.
The important distinction is the control input. You supply a video and a rendered lighting sphere, rather than writing a general editing prompt. This article explains the documented workflow and how to evaluate a first result. H3Vid has not integrated this dedicated endpoint; the instructions below refer to fal's interface and API.
What the lighting sphere does
A sphere provides a compact visual description of how light should fall on a three-dimensional surface. Its bright side, dark side, color transitions, and shadow softness describe a target lighting arrangement. It is a lighting reference, rather than a replacement character portrait or a picture of the desired background.
In the Relight playground, the Lighting studio lets you set light colors, position lights around the subject, and adjust intensity and softness. The studio produces the sphere reference used by the model. If you upload an image instead, the endpoint documentation specifically asks for a sphere render showing the target illumination. An arbitrary mood board is not the documented input.
For a first experiment, choose one clear lighting change. A neutral product shot with a warmer side light is easier to inspect than a moving crowd with several competing neon sources. This is an evaluation strategy, not a claim that the model cannot handle complex scenes.
Prepare the source before designing the light
The current API schema accepts source videos up to 15 seconds. It prepares them at a constant 24 frames per second and trims the end to a compatible frame count of the form 17n+5, leaving at least 56 frames, approximately 2.33 seconds. The generated result follows that prepared clip's duration and frame count.
This means the final frame can differ from the last frame in your original file. Avoid putting an essential logo reveal, gesture, or spoken ending right at the source boundary. Leave room at the end and compare the returned duration before placing the result in an edit. A nominal five-second input should not be treated as a guarantee of an exactly five-second output.
Select a short, self-contained shot whose lighting you want to change. Keep a copy of the original and identify three moments to compare: the opening frame, a frame during the most significant movement, and the ending. For a rotating product, include an angle where a reflective surface or label crosses the key light. That moment reveals whether the lighting change follows the object coherently.
A practical playground sequence
- Open the Relight playground and add the source video.
- Open Lighting studio and start with a simple directional light arrangement.
- Adjust the sphere until its illumination communicates the intended look. Change one variable at a time when evaluating color, direction, intensity, or softness.
- Choose the output resolution and aspect ratio, then submit the render.
- Download the result and compare it with the source at matching timestamps, accounting for any end trim.
For example, a brand-color variation might use a warm white key light and a restrained colored fill. Write down that intention before rendering: the product should remain the same, the rotation should continue unchanged, and only the illumination should take on the new palette. That written note is your review checklist; it is not a prompt field in this endpoint.
Resolution and provider cost
The provider lists native generation at 480P and 768P. Its 1080P and 2K options use latent upscaling and refinement from 768P. Choose the preview resolution according to what you need to judge, then inspect fine edges and text again at the delivery resolution.
At retrieval on October 8, the model page lists rates of $0.05, $0.08, $0.16, and $0.32 per generated second for 480P, 768P, 1080P, and 2K respectively. The page illustrates $0.40 for five seconds at 768P. Billing is duration-based; confirm the current price and prepared output length when estimating a job. These are fal rates, not H3Vid credit prices.
Multiple attempts matter more than the price of one successful clip. Decide on a small preview budget and a clear acceptance criterion before iterating. A higher resolution can make defects easier to see, but does not by itself demonstrate better preservation of motion or identity.
API inputs and asynchronous delivery
The dedicated endpoint is minimax/h3-max/relight. Its required fields are video_url and reference_image_url. It also documents resolution, aspect_ratio, a seed, safety checking, and synchronous data-URI output. There is no general text prompt or requested output duration field in the input schema reviewed for this article.
A minimal input object looks like this; the URLs are placeholders:
{
"video_url": "https://example.com/source.mp4",
"reference_image_url": "https://example.com/lighting-sphere.png",
"resolution": "768P",
"aspect_ratio": "16:9"
}
The API guide supports queued submission, status polling, result retrieval, and an optional webhook. A completed response contains a video file and seed, with inference timing when available. Keep the exact reference image, source, chosen settings, and returned seed together if you plan to revisit an experiment. This example follows documentation; we have not executed a paid generation or verified repeatability.
Review the result as an edit
Check whether the subject's silhouette, clothing, labels, and small details remain consistent. Watch moving shadows, highlights, hands, hair, and reflective materials through the whole shot. Inspect camera framing and the timing of the strongest motion. Finally, listen to the beginning and end of the audio and check its alignment with visible actions.
A clip that looks convincing in a still can still flicker in motion or lose an important detail near the end. Review at normal playback speed as well as frame by frame around transitions. Keep accepted variations beside the source so subsequent editorial decisions remain grounded in the original shot.
For broader changes to the subject, setting, or story, see MiniMax H3 video editing and reference-to-video workflows. Those tools address different controls. Relight's distinctive workflow is existing footage plus a lighting sphere; use that distinction when deciding which editing route to try.
The cover is an AI-generated concept illustration, not a Relight output, screenshot, or tested before-and-after comparison.