image processing with parallel approach

Question

priyam ghosh 2012-2-22

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/29887-image-processing-with-parallel-approach

编辑： Ved 2013-10-20

s=load('matlab.mat','imagest1','imagest2','Train_Number');
imagest1=s.imagest1;
imagest2=s.imagest2;
Train_Number=s.Train_Number;
eyeimage=imread('C:\Users\PRIYAM\Desktop\project\project pictures and links\CASIA Iris Image Database (version 1.0)\002\1\009.bmp');
%imshow(eyeimage)
radpixels=50;
angpixels=1000;
[circleiris, circlepupil, imagewithnoise,] = segmentiris(eyeimage);
[polar_array, noise_array] = normaliseiris(imagewithnoise, circleiris(2),circleiris(1), circleiris(3),circlepupil(2), circlepupil(1), circlepupil(3),...
 eyeimage,radpixels,angpixels);
subplot(2,2,2)
imshow(polar_array)
%imshow(polar_array)
[icodeV,icodeH]=  irisfeature(polar_array);
for i=1:Train_Number
  HD=0;  
    for j=1:500
          HD=HD+((xor(icodeV(1,j),imagest2(i,j))+xor(icodeH(1,j),imagest1(i,j)))/2);
      end
      hd(i)=HD;
end
loc=0;
for i=1:Train_Number
    if (hd(i)<149.5)
     loc=i; 
      fprintf('image matched with image number %d \n with hamming distance %d',loc,hd(i));
      end
end
if (loc==0)
    disp('image not matched with any image');
end;toc

How to parallelize it? I have used parfor, but the exexcution time remains same. Please help me to make the code snippet parallel. What should be the alternative parfor code for it?

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Answer 1

Walter Roberson 2012-2-22

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/29887-image-processing-with-parallel-approach#answer_38296

在 MATLAB Online 中打开

Vectorize, not parfor!

For example,

loc = find(hd < 149.5, 1, 'first');
if ~isempty(loc)
  fprintf('image matched etc');
else
  fprintf('image not matched');
end

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Edric Ellis 2012-2-22

I would say: vectorize first, and then you'll probably be in a better position to use PARFOR if you wish. Plus, of course, vectorization might get you intrinsic multithreading (depending on your operation), which definitely beats PARFOR on a single machine.

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