SetDirectory["C:\\drorbn\\AcademicPensieve\\2013-11\\KVT"]

img=Import["Bear-8.png"]

Dimensions[im=ImageData[img]]

GraphicsGrid[Partition[
Table[
bs=2^(8-k);
ps = Graphics[
Raster[Reverse[Total[Partition[im, {bs,bs}], {3,4}]/bs^2.]
],
ImageSize -> 256, ImagePadding -> None, PlotRangePadding -> None
];
Export["Bear-"<>ToString[k]<>".png", ps];
ps,
{k,0,5}
],2]]