Blending modes: concept
Layer Blending Modes are only available in TVPaint Professional. TVPaint Standard only has the Color Blending Mode available.
A Project's final image or animation is the result of the mixing of all its Layers' pixels together. The mixing of these Layers is applied from the bottom to the top of the Layers list:
But... there may a need to mix the pixels of each Layer in different ways.
With the above example, Layer 3 is applied over the result of Layer 2 and 1. But whereas the colors of Layer 3 are just copied on the resulting Layer, the content of the Layer 3 could Erase, Tint, Saturate... the content of the resulting Layer.
It is already possible to do it in some way, with a limited number of modes. When you drag a Layer over another one and drop it, a popup menu appears and asks how the pixels of the dragged Layer should be mixed with the other Layer. But in this case, the two Layers will be merged and the informations of each Layer will be lost. It is often preferable to keep the Layers separated.
The solution is to mix the Layers but without needing to modify them. To do that, the Layers should be mixed "on the fly". A Blending Mode menu is present for each Layer on the left side of the Layer Stack and allows you to select the way to mix the Layers:
Each Layer has its own Blending Mode, which means each Layer can be blended in a different way with the other Layers. The final image is instantly displayed in the project window and without having to modify something in any Layer!