MapImageLayer - set renderers on sublayers
The sublayers property of a MapImageLayer allows you to dynamically set renderers on the fly for layers in a map service. To do so, you must reference the layer ID of the service layer and assign a renderer to the renderer property of the sublayer.
To see the default renderers for layers in the map service, either remove the references to the renderers defined in this sample or view the MapImageLayer - Toggle sublayer visibility sample.