Repair & refinement

IntermediateDuration ~13 min video + 45 min hands-onTools DaVinci Resolve (free)

Why this lesson

Real footage arrives broken. A fly-on-the-wall documentary shot at ISO-through-the-roof in a dim room, an underexposed run-and-gun clip you have to lift two stops, a jumper that crawls with sensor grain — none of it is clean, and no amount of colour balancing hides it. Repair is the unglamorous layer that sits under the grade: get the signal clean and stable first, then correct and flavour on top. This lesson is the repair mindset done the way a working colourist does it — noise reduction dialled in on scopes rather than by feel, texture managed with mid-detail, and mixed lighting and exposure problems fixed with secondaries — plus the discipline of knowing when to stop before the image goes plastic.

Watch

Watch for: Mostyn grades a real BBC One documentary (Tommy Jessop Goes to Hollywood) and works two clips end to end. First, the discipline: on a one-hour, 661-shot programme he used NR on only 56 clips — under 10% — because he 'avoids it like the plague.' Watch him turn OFF the scopes' low-pass filter so the noise actually shows up on the parade and vectorscope (tip one). Then the temporal pass — frames set to 2 forward / 2 back, motion estimation on Better not Faster — followed by the spatial pass, radius kept small, aiming for a rough half-and-half split of spatial over temporal. Watch the A/B highlight (tip two) that shows only what THAT node is doing, and the moment he calls the result 'plasticky' and dials it back. On the second clip, exposure is fine but a jumper and camera pick up noise: he isolates the shadows-to-mids with a luminance qualifier to protect the face entirely, then adds grain back afterwards for grit.

The explainer

Start with the mindset, because it is the whole lesson: noise reduction is a last resort, not a default. On a one-hour documentary of 661 shots, Mostyn used NR on 56 — under 10% — and only where low light and heavy lifting forced his hand. Repair is surgical, not blanket.

Noise reduction comes in two forms, and they work differently. Temporal NR looks forwards and backwards in time — up to five frames each way — and separates what moves from what doesn’t, so it can clean the still parts of a shot without softening real detail. It is the detail-preserving option when motion estimation is good, but it is heavy: past three frames Mostyn’s fast Mac “grinds to a halt,” so he starts at two and sets the estimation type to Better, never Faster (“we always want the best results”). Spatial NR works inside a single frame, analysing the image and blurring away noise while trying to keep detail. It is more accurate frame-to-frame but softens, and pushed hard it smears. Keep its radius small and build up only if needed. His rule of thumb: aim for a rough half-and-half split, a bit more spatial than temporal — “don’t go exactly half, but somewhere around that ratio.”

Dial it in on the scopes, then off them. Tip one: turn off the scopes’ low-pass filter so the noise actually shows on the RGB parade and vectorscope. Unlink luminance and chrominance, then raise the luma threshold until you hit “the point where it kicks” — the level where more does nothing — and back off a touch. Tip two: use the node’s A/B highlight to see only what that node is doing, and watch the face at 1:1. The failure mode is over-cooking: when skin goes smooth and “plasticky,” you have gone too far. Mostyn dials the amount back rather than reaching for the blend slider, then puts it on and off to confirm he is actually improving the image, not just changing it.

Denoise before you key or grade. He places NR early — right after the CST normally — so every downstream node works on a clean signal. This is the clean-edge discipline from 2.4: qualifiers and keys pull cleaner edges off a denoised image than off a noisy one. But early isn’t dogma. On his first clip, so badly underexposed it needed a big lift, he moved NR to after the lift node — because the lifting is what amplified the noise, so it made no sense to clean before creating it. Position follows cause.

Fix problems locally with secondaries. His second clip had good exposure but a jumper and a camera crawling with grain, while the face looked great. Blanket NR would have smoothed the face too. So he used a luminance qualifier to isolate the shadows-to-mids, kept the highlights out, and softened the qualifier edge — noise gone from the jumper, face untouched. The same secondary thinking fixes mixed lighting and patchy exposure: window and qualify the problem region rather than treating the whole frame.

Then put texture back. Denoising leaves an image soft, so refinement means restoring a little grit — a touch of positive mid-detail for crispness, or added grain (Mostyn adds his in Rec.709 after the CST, with highlights pulled back so the grain sits in shadows and mids). Mid-detail is the gentle counterpart to sharpening: negative to calm harsh skin, positive to add bite. Always finish by toggling the whole thing off and on. If it doesn’t clearly look better, take it out.

Do it

1. Find a genuinely noisy clip — low light, or one you have to lift hard. Normalize with a CST first.
2. Open the Scopes, set parade and vectorscope, and turn off the low-pass filter so noise shows.
3. Add a noise reduction node. If the shot needs a big exposure lift, put NR after the lift; otherwise put it right after normalize.
4. Temporal first: frames at 2, estimation on Better, motion range to match the shot. Unlink luma/chroma, raise luma threshold to the point it stops helping, back off.
5. Spatial next: Better mode, small radius, dial threshold up to roughly half-again of your temporal amount. Use the node A/B highlight and watch skin at 1:1 — stop before it goes plasticky.
6. Go local: on a shot where only part of the frame is noisy (or lit differently), add a luminance qualifier or window so NR hits only the problem area and leaves faces alone. Soften the edge.
7. Refine: add a little positive mid-detail or a grain node (in Rec.709, highlights reduced) to restore texture.
8. Toggle the whole repair off and on. Keep it only if it clearly improves the image.

Scopes field guide — reading the parade & vectorscope while you denoisescopes-field-guide.pdf139 KBOriginal course material — free to useLevel 2 workbook — every Do it exercise, 2.1–2.12, plus the capstone (printable)level-2-workbook.pdf799 KBOriginal course material — free to use

Terms introduced

Terms introduced in this lesson

• Noise reduction
• Mid-detail

Each term links to the glossary, where it is defined by the way you just used it.

Check

Check yourself

1. What is the difference between temporal and spatial noise reduction?

   They are two names for the same controlTemporal compares several frames across time; spatial works within one frameTemporal removes colour noise only; spatial removes luminance noise onlyTemporal works within a single frame; spatial compares across frames

2. Why does Mostyn denoise before keying and grading rather than after?

   So every downstream node — qualifiers, keys, grades — sees a clean signal instead of chasing noiseIt is the only place Resolve allows itNoise reduction only works on the first nodeIt renders faster that way

3. On his second shot the exposure was fine but a jumper and camera picked up distracting noise, while the face looked great. How did he keep NR off the face?

   He isolated the shadows-to-mids with a luminance qualifier and kept the highlights outHe turned the noise reduction all the way downHe used temporal NR onlyHe added grain to the face to hide it

4. What does pushing the mid-detail control negative do?

   Softens harshness and calms busy texture like skinRaises the exposure of the mid-tonesAdds mid-frequency crispness and sharpeningIncreases saturation in the mid-tones

Check answers

You can move on when you can… take a noisy, imperfect clip and repair it in order — denoise with temporal and spatial NR balanced and verified on scopes, place the NR node where the cause of the noise dictates, isolate local problems with a secondary so faces stay clean, and restore texture with mid-detail or grain — then toggle it off and on and honestly say it looks better, not just different.

Mark this lesson complete

Go deeper

Play it, always. Noise reduction — temporal especially — can only be judged in motion, because it works across frames. If real-time playback stutters, cache the node (Playback → Render Cache → User, then right-click the node → Node Cache on) so you can watch the cleaned result at speed before you commit.

Grain is not the enemy of clean. A denoised image often looks too clean and digital. A restrained grain pass, weighted toward shadows and mids, gives back the organic texture the eye expects — the opposite move to NR, in service of the same natural result.

Next up: 2.12 · The honest suite — calibrate what you already own, understand I/O boxes and panels, and buy nothing prematurely.