mCurrentSlicerManager->GetSlicer(0)->GetRegisterExtent(w_ext);
for(int dim=0; dim<slicer->GetDimension() && dim<3; ++dim){
imsize[dim] = w_ext[2*dim+1] - w_ext[2*dim] +1;
mCurrentSlicerManager->GetSlicer(0)->GetRegisterExtent(w_ext);
for(int dim=0; dim<slicer->GetDimension() && dim<3; ++dim){
imsize[dim] = w_ext[2*dim+1] - w_ext[2*dim] +1;