Thanks Rick. I understand that each new layer added is transparent so that layers below can be seen through. However, when you create a layer by duplicating a background with 255 opacity but non-normal blending, I do not understand how the layers below can be seen through unless the blending occurs when the layers are being rendered. In that is case, layers are no seen through. But since the blending occurs for each layer during rendering , the top layer reflects the layers below. If that is case, how can you manage to get the pretty good performance since if you have 10 layers, each layer needs to be blended with the layer below while it is being rendered? Is this how it works?
For ( each layer in layer list)
{
Render layer using blend op with layer below
}