function [params, bg_area, fg_area, area_resize_factor] = initializeAllAreas(im, params)

	% we want a regular frame surrounding the object
	avg_dim = sum(params.target_sz)/2;
	% size from which we extract features
	bg_area = round(params.target_sz + avg_dim);
	% pick a "safe" region smaller than bbox to avoid mislabeling
	fg_area = round(params.target_sz - avg_dim * params.inner_padding);
	% saturate to image size
	if(bg_area(2)>size(im,2)), bg_area(2)=size(im,2)-1; end
	if(bg_area(1)>size(im,1)), bg_area(1)=size(im,1)-1; end
	% make sure the differences are a multiple of 2 (makes things easier later in color histograms)
	bg_area = bg_area - mod(bg_area - params.target_sz, 2);
	fg_area = fg_area + mod(bg_area - fg_area, 2);

	% Compute the rectangle with (or close to) params.fixedArea and
	% same aspect ratio as the target bbox
	area_resize_factor = sqrt(params.fixed_area/prod(bg_area));
	params.norm_bg_area = round(bg_area * area_resize_factor);
	% Correlation Filter (HOG) feature space
	% It smaller that the norm bg area if HOG cell size is > 1
	params.cf_response_size = floor(params.norm_bg_area / params.hog_cell_size);
	% given the norm BG area, which is the corresponding target w and h?
 	norm_target_sz_w = 0.75*params.norm_bg_area(2) - 0.25*params.norm_bg_area(1);
 	norm_target_sz_h = 0.75*params.norm_bg_area(1) - 0.25*params.norm_bg_area(2);
%    norm_target_sz_w = params.target_sz(2) * params.norm_bg_area(2) / bg_area(2);
%	norm_target_sz_h = params.target_sz(1) * params.norm_bg_area(1) / bg_area(1);
    params.norm_target_sz = round([norm_target_sz_h norm_target_sz_w]);
	% distance (on one side) between target and bg area
	norm_pad = floor((params.norm_bg_area - params.norm_target_sz) / 2);
	radius = min(norm_pad);
	% norm_delta_area is the number of rectangles that are considered.
	% it is the "sampling space" and the dimension of the final merged resposne
	% it is squared to not privilege any particular direction
	params.norm_delta_area = (2*radius+1) * [1, 1];
	% Rectangle in which the integral images are computed.
	% Grid of rectangles ( each of size norm_target_sz) has size norm_delta_area.
	params.norm_pwp_search_area = params.norm_target_sz + params.norm_delta_area - 1;

end