How to colorize a black and white video with AI

To colorize a black and white video, run it through an AI video-to-video edit with a prompt such as “Colorize this black and white footage in natural colors. Keep everything else the same.” The model re-renders the clip in color. It has no record of the original colors, so it invents them: name any color that has to be right, and check the result against what you know.

On Sume, that edit is gemini-omni-flash-1.1 on the Video Router, sent your clip's public URL. The facts below come from the Video Router, Video generation, Media inputs and Video filter docs, the FFmpeg filters documentation, and Sume's pricing code, read on 2026-09-29.

How do I colorize a black and white video with AI?

Send POST /v1/video-router/generate with model: "gemini-omni-flash-1.1", the clip's URL in video_url, and the change in prompt. Sending video_url puts the model in edit mode. resolution is optional and defaults to 720p; edit mode takes no aspect_ratio or duration. Edit a video with a prompt covers polling the job and reading the result.

curl -X POST https://api.sume.com/v1/video-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: colorize-001" \
  -d '{
    "model": "gemini-omni-flash-1.1",
    "prompt": "Colorize this black and white footage in natural colors. The car is dark red and the sky is pale blue. Keep everything else the same.",
    "video_url": "https://example.com/old-street-1950.mp4",
    "resolution": "720p",
    "mode": "async"
  }'

How do I get accurate colors?

Tell the model what you know, because anything you leave out is its guess:

• Name the colors that matter: a uniform, a car, a flag, a dress.
• Describe the overall look in plain words, such as natural daylight or warm indoor light.
• End with what stays: “Keep everything else the same”, the wording of the docs' own edit example.
• Compare the result frame by frame with the source. The docs don't promise what else an edit changes, or whether it keeps the source's length, framing or sound.

Can a color filter colorize a video instead?

No. A filter changes pixel values by fixed rules; it cannot tell which gray is skin and which is sky. FFmpeg's colorize filter, for example, overlays one solid color on the whole frame: that gives a sepia or blue tint, not a colorized scene. In current code Sume's Video filter allows colorize among its tone filters, so a tint is possible there, but it is not colorization.

What footage can I send?

The clip must be at a fetchable public HTTPS URL. Localhost, private-network, non-HTTPS, and signed or private URLs are rejected before the job is submitted. video_url is the edit source, so it cannot be combined with image_url, end_image_url or reference URLs.

The docs don't give a source-length limit for edit mode. Try a short clip first and check the output's length before sending a long reel.

How much does it cost to colorize a video?

The edit is billed per second of output by resolution, at the provider's list price × 1.25, plus a 5.5% agent fee by default. The 10-second column is only an example length.