layer "merge visible layers" different result of the treatment

[corinth]

hello
In a "photo persona" treatment I integrated a slap filled with 50% of gray in "bright light" mode (1).
I applied an "add noise" filter at 45%.
When I merged the visible layers I obtained a new layer corresponding to the result of all the layers of settings+(1). I thus processed 15 files.
But suddenly and for no apparent reason, whatever the file, this new layer "merge visible layers" appears with a smoothing of the expected result: the expected noise is lower than the one visible with all the previously created adjustment layers.
Moreover, on the ".af" files where the effect was kept, today when opening these files, when Affinity Photo recalculates, the effect disappears on the "merge visible layers" layer.
I cleaned the PC, deleted and reinstalled Affinity Photo, the problem remains.
Do you know the possible causes?
Thank you!

Translated with www.DeepL.com/Translator (free version)

 

bonjour
Dans un traitement "photo persona" j'ai intégré un claque rempli de 50% de gris en mode "lumière vive" (1).
Je lui ai appliqué un filtre "ajouter du bruit" à 45%  .
Lorsque je fusionne les calques visibles j'obtenais un nouveau calque correspondant au résultat de l'ensemble des calques de réglages+(1). J'ai ainsi traité 15 fichiers.
Mais subitement et sans raison apparente, quel que soit le fichier, ce nouveau calque "fusionner les calques visibles" apparait avec un lissage du résultat attendu : le bruit attendu est plus faible que celui visible avec l'ensemble des calques de réglages créés au préalable.
De plus, sur les fichiers ".af" où l'effet était conservé, aujourd'hui lors de l'ouverture des dits fichiers, lorsque Affinity Photo recalcule, l'effet disparait sur le calque "fusionner les calques visibles".
J'ai nettoyé le PC, supprimé et réinstallé Affinity Photo, le problème subsiste.
Connaitriez-vous les causes possibles ?
Merci !

[MEB]

Hi corinth,
Make sure you are checking the file at 100% zoom or higher when comparing the before and after merge operation. Affinity Designer/Photo uses mipmaps - lower resolution versions of the image/layer - to improve its performance when rendering images on screen at zoom levels below 100%. So what you see on screen is the result of those filters or in this case Noise (which is also dynamic) being applied dynamically to the lower resolution versions of the image/objects (depending on the zoom level). When you merge the layers the filters/adjustments/noise are backed to the full resolution image instead thus the differences you are seeing between the two. To prevent this from happening and get an accurate "preview" of the filters/adjustments/noise make sure you are seeing/checking them at 100% zoom or more to ensure they are being applied/previewed using the full resolution version.