rendering Kernel Density raster

This is also posted in the cartography forum but no replies so I thought I'd try here.

I have written a Python toolbox tool which among other things generates a raster via the Kernel Density tool. I have a .lyr file which is applied by the tool to the output. The .lyr sets the color palette and specifies an 8-class Natural Breaks classification. I've noticed that when the symbology is applied by the Python toolbox tool the resulting raster is very pixelated and generally looks pretty bad in ArcMap, but when I manually (ie. right-click, properties, apply symbology from .lyr) take that same output and apply that very same symbology using the exact same .lyr file, the raster is rendered very smoothly and looks quite nice.

Does geoprocessing use a different renderer than the layer properties dialog? Is there a way I can control how smoothly the raster is drawn via my Python code or via Geoprocessing options? The whole point is to automatically create a visually appealing result for the user but the way the surface is being rendered looks terrible unless I manually change it.