vImage.BlendMode.darken
Sets each channel of the destination pixel as the darkest value for the corresponding channel of the two source layers.
Declaration
case darkenDiscussion
The following image shows the result of compositing using the darken blend mode:
[Image]
The bottom-right quadrant in the result is black because no pixels in the bottom layer are darker than the corresponding pixels in the top layer.
The bottom-left quadrant in the result looks darker than the corresponding quadrant in the bottom layer. This is because the operation selects gray pixels from the top layer over corresponding light pixels from the bottom layer.