Layer Compositing

Layer compositing is implemented by alpha-blending a stack of premultiplied RGBA32 images. The result is a single premult. RGBA32 for being displayed on screen. All images are composed on top of an opaque white base layer.

The image format "premultiplied RGBA32" is carefully chosen. For the rationale why, please read the Image Compositing Fundamentals. As of the time of writing, the ImageScene2D class is responsible for layer compositing (see: https://github.com/Ilastik/volumeeditor/blob/master/volumeeditor/imageView2D.py).