Specifying Input Layers

Layers are passed as input to commands as JSON strings with the following format:

Optional keys:
 "type": str from ["img", "mask", "field"] ;
 "name": str, DEFAULT -- same as layer type.
         [required] if given more than 1 layer of the same type ;
 "args": a dictionary with additional layer parameters,
               eg binarization scheme for masks data_mip_ranges, etc;
Required keys:
 "path": path to the layer data;