steerchannels.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, ch, combineGH] = steerChannels(ipyr, ch)
%foo
  
%if not pyramid input
  if(strcmp(class(ipyr),'cell')==1)
    pyr = ipyr;
  else
    pyr{1}=ipyr;
  end
  
  combineGH=0;
  if(ch<0)
    combineGH=1;
    ch=-ch;
  end
  
  if(length(ch)==1)
    ch = linspace(-pi/2, pi/2, ch+1);
    ch = ch(1:end-1);
  end
  
  for l=1:length(pyr)
    theta =[]; strength=[]; G2=[]; H2=[];
    im = mean(pyr{l},3);
    basis = steerable_gauss(im,1);
    for d=1:length(ch)
      [G2 H2] = steer(ch(d),basis);
      if(combineGH)
	fpyr{l}(:,:,d,1) = sqrt(G2.^2+H2.^2);
	fpyr{l}(:,:,d,2) = abs(atan2(H2,G2));
      else
	fpyr{l}(:,:,d,1) = G2;
	fpyr{l}(:,:,d,2) = H2;
      end
    end
    if(combineGH)
      maxmap = max(fpyr{l}(:,:,:,1),[],3)+eps;
      fpyr{l}(:,:,:,1) = min(0.4,fpyr{l}(:,:,:,1).^2./...
			     repmat(maxmap, [1,1,length(ch)]));  
    else
      maxmap = max(max(abs(fpyr{l}),[],4),[],3)+eps;
      fpyr{l} = max(-0.4, min(0.4,fpyr{l}.*abs(fpyr{l})./...
			      repmat(maxmap, [1,1,length(ch),2])));  
      
    end
  end
  
  if(strcmp(class(pyr),'cell')==1)
    fpyr = fpyr{1};
  end