i = RandomReal[{0, 1}, {100, 100, 100}];
Do[i = Rescale[i - GradientFilter[i, 2]];
t = 2 Pi j/300.;
Export["image_" <> ToString[j] <> ".bmp",
Rasterize[
Image3D[i^10, ViewPoint -> {3 Cos[t], 3 Sin[t], 2},
SphericalRegion -> True], ImageSize -> {300, 300}]], {j, 800}]