Thirty renders, one world

Why every clip is a different colour

Nothing carries colour decisions between generations. Two clips from the same still, the same prompt and the same model will differ slightly in white balance, contrast and saturation, because those properties emerge from the sample rather than being set by a parameter.

Across thirty clips generated over a week, that variation is large. On a timeline it reads as amateurism more reliably than almost any other fault, because audiences associate consistent colour with produced work.

Two stages, in this order

The mistake is to grade each shot until it looks nice. That produces thirty attractive shots that do not belong together.

Stage one: match. Bring every clip to a neutral common ground. Same black level, same white point, same rough contrast. Nobody sees this stage; its output looks flat and boring and correct.

Stage two: grade. One look, applied across everything at once, on an adjustment layer. This is where the piece gets its colour.

The reason for the order: a look applied to inconsistent clips amplifies the inconsistency, because a contrast curve pushes two different starting points further apart.

Doing stage one

Pick a hero shot (the one closest to what you want, usually a well-exposed mid-shot) and match everything to it.

In DaVinci Resolve’s free tier:

1. Put the hero shot and the shot you are matching side by side, using the split-screen view on the colour page.
2. Right-click the target clip and use Shot Match to that hero. It does most of the work in one click.
3. Fix what it got wrong by hand, in this order: black level first, then white point, then mid-tone brightness, then saturation.

Black level first matters. If the blacks do not sit at the same level, every subsequent adjustment is fighting a mismatch you have not fixed. Use the waveform scope: find the bottom of the trace in each clip and line them up.

Kdenlive and Shotcut have colour-balance and curve filters but no shot-match. The manual method works: set the scopes side by side, match blacks, match whites, match saturation. Slower, same result.

Reading scopes instead of your eyes

Your eyes adapt within seconds, which makes them useless for comparison. After thirty seconds of looking at a warm shot, a neutral one looks blue.

Scopes do not adapt:

• Waveform shows brightness across the frame. Use it for black level and white point.
• Parade shows red, green and blue separately. Use it for colour cast: if the blue trace sits higher at the bottom than the red, the shadows are blue.
• Vectorscope shows hue and saturation. Skin tones fall along a specific line on it, which is the most useful single fact in colour correction: if your skin tones sit on the skin line, the shot is close to right.

Resolve’s free tier has all three. This is professional colour instrumentation at no cost, and most people using it never open them.

Stage two, the grade

One adjustment layer over the whole timeline, carrying the look from your look file. Typically:

• A contrast curve, usually lifting the blacks slightly so nothing is pure black.
• A colour shift: warm highlights and cool shadows is the most common, and the most over-used.
• A saturation adjustment, usually downward.

Keep it modest. A strong grade on generated footage draws attention to the footage, which is the opposite of what you want.

The secondary you will eventually need

When one element is wrong while the rest of the frame is right (a garment that came out a different blue in one shot) a global correction cannot help.

A secondary isolates a colour range or a shape and corrects only that. Resolve’s free tier supports qualifiers and windows, including tracking a window across a moving subject.

It is fiddly, it is imprecise on anything with motion blur or soft edges, and it is sometimes the only thing between you and regenerating the shot. Budget an hour when you need one, and treat needing one as a signal that your still-checking pass failed.

Check on more than one screen

A laptop screen, a phone and, if possible, a television. Generated footage graded on a bright laptop routinely looks crushed and muddy on a phone in daylight, which is where most of your audience is.

If you can only check on one screen, check on the phone.

Today: open the waveform scope, put three of your clips on a timeline, and line up their black levels. Do nothing else and watch how much more like one piece they look.