steerfilterpyr.m

加州大学伯克利分校的一个车俩识别程序, 用matlab实现

function fpyr = steerFilterPyr(ipyr)
% fpyr = steerFilterPyr(pyr)
% make filtered pyramid steered towards maximum energy from image
%   pyramid
% pyr   image pyramid (cell array of images)
%       where images may have multiple channels (z coord)
% returns filtered image pyramid where each image has 3 channels:
%   (theta_max, G2^2, H2^2)
% if image was multi channel (eg RGB), theta_max is the enegy max of
%      direction and channel while G2=sum(G2(:,:,channels).^2); 
% 

  %if not pyramid input
  if(strcmp(class(ipyr),'cell')==1)
    pyr = ipyr;
  else
    pyr{1}=ipyr;
  end
  
  for l=1:length(pyr)
    theta =[]; strength=[]; G2=[]; H2=[];
    for c = 1:length(pyr{l}(1,1,:))
      basis{c} = steerable_gauss(pyr{l}(:,:,c),1);
      [theta(:,:,c) strength(:,:,c)] = steer_max(basis{c});
    end
    [e,z] = max(strength,[],3);
    [x y]= meshgrid(1:size(strength,2),1:size(strength,1));
    I = sub2ind(size(strength),y,x,z);
    fpyr{l}(:,:,1) = theta(I);
    for c = 1:length(pyr{l}(1,1,:))
      [G2(:,:,c) H2(:,:,c)] = steer(fpyr{l}(:,:,1),basis{c});
    end
    fpyr{l}(:,:,2) = sum(G2.^2,3)/3.0;
    fpyr{l}(:,:,3) = sum(H2.^2,3)/3.0;
  end
  
  if(strcmp(class(ipyr),'cell')==0)
    fpyr = fpyr{1};
  end