Setting RenderGlobals imageFormat?

[Anonymous]

I'm using Maya 2012 for Windows and rendering with renderMan. I need to set the
RenderGlobals image Format to Tiff8.

pycore.setAttr( "defaultRenderGlobals.imageFormat", 3 ) should set the image format
to Tiff8, but the images are rendered as iff.

The imageFilePrefix command works fine ( see command below ).
pycore.setAttr( "defaultRenderGlobals.imageFilePrefix", outputImageName, type="string" )


Any ideas?

Thanks.