Understanding layer modes
At their most basic level, layer modes (also known as blending modes or layer blending modes) are just rules in which two layers (or more, if dealing with layer groups) interact with one another using algorithms and computer logic within Krita. For instance, the default blending mode within Krita (known as the Normal mode) has the basic logic of "If a layer is above another layer on the Layers panel, display the contents of the top layer on top of the contents of the layer below it, with relation to the transparency of the top layer's contents."
This may not seem like something useful just from the definition, however, this is a powerful benefit of working digitally. Layer blending modes are extremely valuable to learn, as the flexibility they provide can take your art to the next level by adding realistic texturing, controlling more subtle light and shadow usage, and integrating photographs into your compositions, for example.
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