Non-uniform colours: almost always a coefficients story
A brighter square after a module replacement, checkerboard tint variations, white turning pink on one side: these uniformity defects almost never come from the LEDs themselves, but from the calibration coefficients — the per-pixel corrections stored in the wall.
Why a wall needs calibration
Two LEDs of the same model never produce exactly the same brightness or tint: manufacturers sort by batches (binning), then measure every pixel in the factory and store an individual correction.
These coefficients live in the receiving cards or in a file tied to the wall. While they are in place, the wall is uniform. Lose them — card or module replacement, wrong operation — and batch differences become visible again.
The three classic scenarios
After a module replacement: the new module shows its batch's raw tint. Apply its own coefficients (delivered with the module or measurable) or reload the zone's calibration.
After a receiving card replacement: the new card arrives without the cabinet's coefficients. Reload them from backup before anything else.
Gradual drift on an ageing wall: blue LEDs age faster; a full on-site camera calibration restores years of uniformity.
The right reflexes, in order
- Before any work on cards or modules, back up the configuration AND the calibration coefficients. That is the golden rule.
- After a replacement, first reload the coefficients (in NovaLCT: Manage Coefficients; equivalents in other ecosystems) before judging the result.
- If a module still stands out, check its own coefficients were applied to its exact position.
- For global drift, have an on-site camera calibration done rather than manual zone-by-zone touch-ups.
- Never overwrite coefficients without a prior backup: the operation is irreversible.
When to call an engineer
Coefficients nowhere to be found, inherited wall without backups, generalized checkerboard after an update: an engineer can often recover the data (manufacturer cloud, factory files) before considering a far more expensive full recalibration.
A failure right now? Lédia, our AI engineer, guides you step by step, 24/7, photos included.
Talk to LédiaSee pricingFrequently asked questions
Can I fix a brighter module by lowering its brightness in the software?
The classic false good idea: eye-balled correction holds neither over time nor across content. The only durable fix goes through the module's calibration coefficients.
Does replacing a module always require recalibration?
No. If the module arrives with its factory coefficients and you apply them to its position, uniformity is preserved. Full recalibration is only needed for global drift or lost data.
What exactly is « mura »?
Patchy luminance or tint irregularities, most visible on grey fills and slow camera moves. It is the signature of absent, partial or outdated calibration.
Does calibration reduce maximum brightness?
Yes, slightly: aligning all pixels on a common target consumes a brightness margin, typically 10 to 20%. That is the price of a uniform wall.