How to make your subject stand out from the background

Last updated 2026-08-30 · 7 min read

What is the short version?

Footage shot on a phone is flat: the subject and the background sit at the same apparent distance, so nothing draws the eye. Separating them is a compositing job — build a matte, treat the two layers differently, and put them back together.

1. Go to Vizard Agent and upload the clip.
2. Say the subject should stand out and the background recede.
3. Say how strong the effect should be.

What do you need before you start?

The clip and a sense of how far to push it. Vizard Agent works out the separation from the footage itself, so no depth map or green screen is required, but the strength is a taste decision that it cannot make for you.

• The clip. As filmed, however flat.
• The subject. What should come forward.
• The strength. Subtle, or unmistakable.
• What must not change. Colour, skin tone, the grade.
• The output. Same shape and length, usually.

What do you type into Vizard Agent?

Describe the result rather than the technique. Vizard Agent picks the method — a matte, selective treatment, a depth-style separation — from what you describe, and "make the foreground stand out and feel further from the background" is a complete brief.

Prompt

Variants worth knowing:

• Tested on one frame first. Before the whole clip is processed.
• Colour explicitly preserved. So the separation does not desaturate anything.
• A stronger or subtler pass. Once you have seen the first.

What does Vizard Agent actually do?

Here is the order Vizard Agent worked in on a real depth-separation job. Most of it is debugging in public: the first composite worked and quietly turned the picture grey, and the rest of the session is finding out why.

1. Checks the clip's duration, size and format before editing anything.
2. Checks the available guidance for foreground and background separation.
3. Samples the clip at several moments so the subject can be preserved throughout.
4. Looks at the sampled frames to decide how strongly to separate them.
5. Tests a matte on one representative frame rather than the whole clip.
6. Reads the exact filter error when the test fails, and corrects it.
7. Finds the real cause — the split filter needed an explicit output count — and switches to clearer stream labels.
8. Isolates the filter graph to confirm how this build handles the split, then divides the stream into three branches.
9. Checks the mask for gaps, reviews the composite, discovers it has lost colour, traces which branch is becoming greyscale, switches to a colour-preserving composite and verifies it with channel averages.

Step 9's ending is the part worth taking away. A preview that looks slightly desaturated might be the effect working or might be a fault, and measuring the channel averages settles it in a way that looking at the picture never will.

What does the result look like?

A version of your clip in which the subject sits forward and the background falls away — more contrast between the two planes, the background softened or darkened depending on the strength you asked for, and the subject's own colours unchanged.

The clip is otherwise identical. No recomposition, no crop, no regrade of the whole frame: the only difference is that your eye now goes where it should.

When does this not work well?

Separating a subject from a background that was never actually separate is an estimation, and some footage gives Vizard Agent very little to base that estimate on. These are the situations where the effect either fails or announces itself.

• Similar tones defeat the matte. A dark coat against a dark wall has no edge.
• Fine detail suffers. Hair and loose fabric are where mattes fail.
• Motion blur has no boundary. Fast movement smears across the separation.
• Overdone, it looks cut out. Too much strength reads as a bad composite.
• Depth cannot be invented. This enhances a difference; it does not create one.

How do you fix a result that came back wrong?

Say what looks wrong to you, in ordinary words. Vizard Agent keeps the tested matte, all the sampled frames, the working filter graph and the channel measurements, so the strength or method can change without repeating the diagnosis.

• "It looks cut out." The strength is reduced and the edge softened.
• "The colours went flat." Re-composited with the colour-preserving method.
• "His hair has gaps." The matte is refined and re-checked on those frames.

How does Vizard Agent compare to doing it yourself?

By hand this means building a matte in an editor, applying separate treatments to two layers, and then wondering whether the slightly duller look is the effect or a mistake. Most people give up and add a vignette.

Common questions

Do I need a green screen? No. Vizard Agent builds the separation out of ordinary footage.

Will it change the colours? It should not. Vizard Agent verifies the colour survived rather than trusting the preview.

How strong should the effect be? Subtle, usually. Vizard Agent will go further, but overdone separation reads as a mistake.

Does it work on any subject? Best where subject and background differ in tone. Similar tones give Vizard Agent's matte nothing.

Can I see a test first? Yes. Vizard Agent tests on one frame before processing the whole clip.

Why measure the channels instead of just looking? Because a mildly desaturated preview is exactly what both a working effect and a broken composite look like. Channel averages tell you which one you have in a second.

Does it blur the background? It can. Tell Vizard Agent whether you want softening, darkening, or both.

What about hair and loose clothing? Those are the hard edges. Vizard Agent checks them and reports where the matte struggles.

Can I combine it with a grade? Yes, and it usually helps. The separation gives the grade something to work with.

Does this replace shooting with a wide aperture? No, and it should not. Vizard Agent enhances a separation the lens already gave you; footage shot with real shallow depth of field will always separate more convincingly than footage treated afterwards.

Will this help footage that is simply dull? Partly. Vizard Agent adds depth, not interest, so a flat shot of something uninteresting comes back as a separated shot of something uninteresting.

Can this be applied across a whole series? Yes. Vizard Agent keeps the tested settings, so the same strength of separation can be applied consistently to every video rather than judged afresh each time.

Does Vizard Agent check the result? Yes. It reviews the composite and the colour before delivery.