Resolve Shot Match not working: what to check

Shot Match fails in a small number of predictable ways, and Blackmagic documents nearly all of them in its own manual. In rough order of how often they bite: the clips are still log, you skipped the automatic balance pass the feature was designed to run after, the clips being matched already carry grades or LUTs, the reference clip is itself the problem, the exposures are too far apart to bridge, or the backgrounds are too different for the algorithm to read. Work down that list before concluding the tool is broken. Shot Match is a statistical estimate with documented limits, not a solver.

The clips are still log

Blackmagic states that Shot Match "works best with normalized clips," and that if your timeline is cut from log encoded material you should use DaVinci Color Management to normalize everything before running it. The reason is given too: the algorithm was "developed to provide optimal results when working in the Rec. 709 color space, and at a gamma of 2.4."

It gets stricter when formats are mixed. The manual says Shot Match "is not the right tool to use to try and match un-normalized log-encoded clips that use different types of log encoding, such as LogC and RedLogCine, or to try and match normalized and un-normalized clips," because log encoding behaves like a set of red, green and blue curve operations the algorithm is not equipped to unpick.

So a timeline with S-Log3 from one body and C-Log3 from another, both untouched, is the documented worst case. Normalize first. What counts as normalizing is covered in why CST, ACES and LUTs look different, and what it is worth in stops is the difference between a residual of roughly 0.04 and a median error of 0.853.

You skipped the step it was built to run after

Shot Match is not designed to be used cold. The manual is explicit: the updated version "has been designed to be used after you've used the A button on each clip in the operation, on both the clips you're matching and the clip you're matching to."

That A button is Auto Color, in the lower left of the Primaries palette. It gives each clip a neutral starting point, so Shot Match compares two balanced images rather than two arbitrary ones.

Most people reporting poor results have never done this. They select a range of clips, right click the good one, and expect the algorithm to bridge the whole gap in one move. Run Auto Color first, then match.

Something in the chain is already graded

The manual states that Shot Match "is not designed to apply corrections to clips that already have node adjustments. The results will be unpredictable, and probably won't match." The clips being matched should be completely ungraded.

The reference clip is allowed a correction, with a limit: "for the best results, you should limit yourself to simple Lift/Gamma/Gain primary adjustments. If you make Custom curve or secondary adjustments to the image, it will be much more difficult for Shot Match to give you a good result."

A conversion LUT in a node counts too: the values Shot Match reads have already been clipped and reshaped by that table.

The reference clip is the one that is wrong

Shot Match does not evaluate whether the clip you pointed at is any good: it "isn't supposed to make your clips look good, it's supposed to make them look the same as the clip you choose to match to."

Match a scene to a shot that is a little green and a stop hot and you get a scene that is consistently a little green and a stop hot. Grade the reference to something you would happily deliver before matching anything to it.

There is a trap in the opposite direction. Blackmagic advises against running Shot Match on shots that already share lighting, because the algorithm may make a small adjustment that leaves them matching less well: "Think of Shot Match as a tool for matching clips that look different."

The exposures are too far apart to bridge

Shot Match "has been designed to do no harm to the image," which is the behaviour most often mistaken for a bug. The manual gives the scenario: point it at an underexposed interior and an exterior at high noon, and the algorithm "will do its best to 'split the difference' in order to make the difference between these two clips less jarring, while at the same time taking care not to stretch the color and contrast adjustments being made to the underexposed clips to the point where the image falls apart."

So it undershoots on purpose, protecting your shadows from being stretched into noise. If you want the full match and will pay for it in grain, make that trade yourself.

If the result instead comes back with blown highlights and heavy contrast, check the Color panel of the User Preferences for the "Use Legacy Auto Color/Shot Match" checkboxes. With legacy behaviour enabled, Resolve neutralizes the darkest and brightest levels and then adjusts Master Lift and Master Gain "to maximize image contrast at the outer boundaries of 0 and 100 percent." Pushing everything to the edges of the range is what people describe when they say Shot Match destroys their highlights, and it is a different algorithm from the current one.

The background is doing the matching

The algorithm reads the whole frame, not the faces.

Blackmagic warns to beware of clips with large areas of background color that do not match the other angles, offering a shot reverse shot between someone in a back yard and someone against a purple wall as its example, and noting that this kind of color distribution "can often throw Shot Match results off."

Any scene with a strong wall, a lit backdrop or a block of costume colour on one side of the cut falls into this, and there is no setting for it. Match those angles to each other rather than across the mismatch, or finish by hand.

The adjustment is invisible and sits in one node

This explains why you cannot inspect the result. Shot Match "doesn't apply adjustments to any of the user-editable controls in the Color page. Instead, the image adjustment created by Shot Match is applied invisibly, as the very last adjustment to the node that was selected when Shot Match was used, similar to a LUT."

So whichever node was selected carries the match. If that node held your look, the match lands after your creative work rather than before it, so select a clean node upstream first. You cannot pick the result apart with the wheels afterwards either, and each clip has its own undo stack, so a Shot Match applied across many clips cannot be undone in one action.

Prepare in this order

Normalize every clip through color management so the timeline sits in one space at Rec.709 gamma 2.4. Run Auto Color on the reference and on each clip you intend to match. Grade the reference using primary adjustments only. Select a clean node on the clips being matched, then right click the reference and choose Shot Match to This Clip.

Blackmagic's advice is to work one angle at a time and test on a single clip before committing a batch.

When it still fails

Sometimes it just does. Shot Match produces a statistical estimate, and two frames can be genuinely irreconcilable, as when one camera clipped a highlight the other retained.

The honest options then are to match by eye on scopes, to hand roll a smaller subset, or to change what you match to. Deciding how much of a timeline really needs that attention is do you have to color grade every clip. Matching across camera brands is its own problem before you reach the tool, covered in why your cameras don't match. Clips with a look already baked into the file are harder again, handled in matching log footage to baked-in LUT clips.

Leumos AI, our browser-based grading studio, comes at this differently: rather than matching clip to clip, it detects shot changes in an uploaded edit and grades each shot toward one reference image, then renders the result. That changes the failure mode rather than removing it, since a reference image cannot recover a clipped highlight either. It is in closed beta with a waitlist at leumos.ai, and how automated shot matching works covers the mechanism.

Frequently asked questions

Why is Resolve Shot Match not working on my log footage?

Because it was not built for un-normalized log. Blackmagic states that Shot Match works best with normalized clips, was developed for Rec.709 at gamma 2.4, and is not the right tool for un-normalized log clips using different encodings.

Why does Shot Match only get halfway there?

That is deliberate. The feature is designed to do no harm, so when two clips are far apart in exposure it splits the difference rather than stretching an underexposed shot until it falls apart. If you need the full match, make that adjustment yourself and accept the noise.

Where does the Shot Match adjustment actually live?

It is applied invisibly as the very last adjustment inside whichever node was selected, similar to a LUT, and populates none of the normal Color page controls. Select a clean node first, or the match sits on top of your creative grade rather than underneath it.

Why did Shot Match blow out my highlights?

Check whether the legacy algorithm is enabled in the Color panel of the User Preferences. Legacy Shot Match neutralizes the darkest and brightest levels and adjusts Master Lift and Master Gain to maximize contrast at the outer boundaries of 0 and 100 percent, pushing values to the edges of the range.

Sources

• DaVinci Resolve 20 Reference Manual, Blackmagic Design, chapter on Automated Grading Commands and Imported Grades. Source of every quoted line above, plus the Auto Color prerequisite, the one angle at a time advice, the per clip undo stacks and the legacy algorithm description.
• Thread behind this piece: Resolve shot match not working on r/davinciresolve, corroborated by the autocomplete suggestion "shot match davinci resolve not working".