Why does the following code
Graphics[Raster[{{Hue[1], Hue[1/3]}, {Hue[2/3], Hue[1/6]}}]]
not produce any output? In Mathematica < 6 RasterArray was able to handle this and produced the same output as
Graphics[Raster[{{{1, 0, 0}, {0, 1, 0}}, {{0, 0, 1}, {1, 1, 0}}}]]