Should the black re-separate into the CMY, so that you have the "black" being made of 100% CMY... or is it just drop out the K and the existing CMY data will be all that is needed? As the current trend is to create CMYK images with a higher GCR component, simply dropping out the K data can lead to less than ideal results. If these are cartoons and you don't want four colour black - would you not wish to have single K keyline with no underlying CMY, rather than totally remove it? Perhaps I am not understanding...
Stephen Marsh