merge_k:increase this to give the error mask more weight (i.e. reduce potential misalignment artifacts)
merge_n:increase this to instruct the error mask that small errors are likely noise and can be ignored
blur0:these blur parameters control the size of the feature detection context (patch size) on different scales. 0 is the finest and 3 the coarsest.
blur1:
blur2:
blur3:
sub:if the image is not raw, determines the subsampling block size side length. bayer will always use 2x2 and xtrans 3x3.
