Wie in vorherigen Abschnitten beschrieben, ist die kombinierte Maske eines Moduls (die Kombination jeder gezeichneten und parametrischen Maske) ein Graustufen-Rasterbild. Dieses beschreibt die Wirkung des Moduls auf jedes einzelne Pixel. Die Maske wird für aktive Module gespeichert und kann anschließend in anderen Modulen der Pixelpipe wiederverwendet werden.
Wie mit jeder Maske, wenn der Deckkraft-Wert für ein Pixel in einer Rastermaske null ist, wird die Eingabe in dieses Modul an die Ausgabe ohne Änderung weitergegeben. Wenn der Wert der Deckkraft 1. 0 ist, dann hat es den vollen Effekt. Für alle Werte dazwischen ist der Effekt an dieser Stelle proportional.
Enable the raster mask from its tab and choose a source from the combobox. Raster masks can be identified by the name of the module against which they were originally generated.
Combining with drawn and parametric masks
In Ansel, a raster mask is no longer a mutually-exclusive mode: it can be combined with a drawn and/or parametric mask on top. When you do, the raster mask serves as the base, and the drawn and parametric masks refine it — their opacities are multiplied together pixel-by-pixel. Because masks combine multiplicatively, adding a drawn or parametric mask on top of a raster mask can only restrict its area further, never extend it.
This lets you reuse a mask computed elsewhere in the pipeline (for instance a luminance or edge mask produced by another module) and then trim it to a region with a drawn shape, or restrict it by color with a parametric mask, without having to rebuild it from scratch. In Darktable, selecting a raster mask disabled the other mask types entirely.
Note: Raster masks are generated as part of a module’s internal processing. Once a module’s processing is complete its mask then becomes available to subsequent modules in the pixelpipe.
Das hat zwei Auswirkungen:
Raster masks cannot be generated by disabled modules since they do not participate in pixelpipe processing. As soon as you disable a module, its mask is no longer available for use.
Raster masks are passed up the pixelpipe after module processing – they can only be used by modules that come later in the pipe than the generating module.