How to recolour one thing without catching everything that looks like it

Last updated 2026-08-30 · 7 min read

What is the short version?

Changing one colour in a video is a matching problem, not a painting problem. Gold text and an orange planet are far closer in pixel values than they look to a person, so the whole job is finding a rule that separates them.

1. Go to Vizard Agent and upload the video.
2. Say which element changes colour, and to what.
3. Name the things that look similar and must be left alone.

What do you need before you start?

The video and a precise instruction. Vizard Agent measures the colours itself rather than relying on your description, but it needs to know what counts as a mistake, because a rule that catches the target will usually catch its neighbours too.

• The video. Any length; longer means more checking.
• The target. What changes, described plainly.
• The new colour. A name or a value.
• The exclusions. Everything warm-toned that must stay.
• Where it appears. If you already know.

What do you type into Vizard Agent?

Name the exclusions in the same sentence as the target. Vizard Agent treats those as the test it has to pass, and without them a colour key that looks right on one frame quietly repaints half the background on another.

Prompt

Variants worth knowing:

• A specific target value. If you know the hex code.
• Time windows. When the element only appears in places.
• A tested sample first. Before the whole video is processed.

What does Vizard Agent actually do?

Here is the order Vizard Agent worked in on a real single-colour change across a 73-second video. The step that separates this from a blanket filter is the eighteenth: after the first test, it measured which pixels had turned blue by mistake.

1. Takes a first look at the video and pulls frames to find where the target appears.
2. Measures the exact colour of the target and maps when it is on screen.
3. Compares the text's gold against the planets' orange tones to see how close they are.
4. Re-extracts the frames correctly and measures the colours again.
5. Hunts for the target pixels directly in individual frames.
6. Scans every second of the video for pixels matching the target colour.
7. Checks the colour-key filter options and grabs full-size test frames.
8. Applies the recolour to sample frames and reviews text, planet and ship frames.
9. Measures which engine-dome pixels wrongly turned blue, zooms into both windows where the ship appears, and narrows the key until only the text changes.

Step 9 is the difference between a job done and a job that looks done. A recolour that is correct on the frames you happened to check can be badly wrong twelve seconds later, and the only reliable test is measuring the pixels that should not have moved.

What does the result look like?

From the run this page is written from, probed on the delivered file: 2560x1440, H.264, 30fps, 73.35 seconds, AAC audio. Seventy-three seconds in which every piece of gold text now reads blue, while the planets, the ship's engine glow and the red logo sit at exactly the values they started at.

Nothing else in the frame moved. That sounds obvious and it is the hard part — a naive colour swap on this footage turns the engine domes blue in two separate shots, and neither of them is anywhere near the text.

When does this not work well?

Separating one colour from another that sits close to it in the same frame has a real mathematical limit, and Vizard Agent will tell you where that limit falls rather than delivering a result that only half works and leaves you to find the rest.

• Identical colours cannot be separated. If the text and the planet match exactly, no key divides them.
• Compression blurs the edges. Letters get a fringe of in-between values.
• Motion blur spreads the target. A moving element smears across the threshold.
• Semi-transparent elements blend. Glows take on whatever is behind them.
• Long videos need full scanning. A rule tested on ten frames is not tested.

How do you fix a result that came back wrong?

Name the thing that changed colour and should not have. Vizard Agent keeps the measured colour values, the per-second scan, all the test frames and the mis-keyed pixel measurements, so the rule can be tightened without reprocessing from scratch.

• "The engines went blue." The key is narrowed against the measured dome pixels.
• "Some text was missed." The scan is widened and re-tested on those frames.
• "Wrong shade of blue." Re-applied at a different value; the key stays.

How does Vizard Agent compare to doing it yourself?

By hand this means a colour-key effect, a threshold slider, and scrubbing the whole video looking for places it went wrong. The scrubbing is the part that gets cut short, which is why so many recoloured videos have one shot where the background changed too.

Common questions

How does Vizard Agent find the colour? Vizard Agent measures the actual pixel values rather than working from your description of the shade.

Will it catch every instance? Vizard Agent scans every second of the video for matching pixels rather than sampling frames.

What if something similar gets recoloured too? Name it up front. Vizard Agent measures the exclusions and narrows the key until they survive.

Can I give an exact target colour? Yes. A hex value works, and Vizard Agent matches to it precisely.

Does it work on text and objects both? Yes. Vizard Agent uses the same method; text is easier because its colour is usually flat.

Why measure the mistakes instead of watching for them? Because a wrong recolour on a dark object in a fast shot is easy to miss on playback and obvious once the video is published. Measuring which pixels moved gives the same answer every time.

How long can the video be? Any length. Longer footage means more scanning for Vizard Agent, which is where the time goes.

Can it change several colours at once? Yes, though each one needs its own measurement and its own exclusions.

What if the element is semi-transparent? Harder. A glow takes on the colour behind it, so Vizard Agent has fewer clean pixels to key on.

Can I see the test before the whole video is processed? Yes, and it is worth asking for. Vizard Agent applies the recolour to sample frames first, so you can look at the text, the exclusions and the awkward shots before committing the full render.

Does Vizard Agent check the finished video? Yes. It reviews the recoloured frames and the excluded elements before delivery.