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john
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Does anyone do research on structured light? How to get a good edge detection?

Asked by john
on 10 May 2013
Latest activity Commented on by Camilo
on 13 Aug 2018

My research recently is focus on using color stripe to detect 3d model. I generate a color stripe using De Bruijn sequence. But the edge detection is not as good as I expected.I am afraid this image could not be edge detected well, it is the first important step to process! How to get a good image?My aims is to detect the edge between color stripes?

   %% initialize
   clear;close all;clc;
   I = imread('small2.jpg');
   I2 = rgb2gray(I);%I2 gray image 
   I3=I2;
   figure(1);
   image(I);
   axis image;
   N=size(I);
   %Notice our stripe is vertical, so we check every column to detect edges.
   R=I(:,:,1);
   G=I(:,:,2);
   B=I(:,:,3);
   %% edge detection
   %threshold
   TS=10;
   for i=1:N(1)  %row
      for j=2:N(2) 
          Defference=abs(R(i,j)-R(i,j-1))+abs(G(i,j)-G(i,j-1))+abs(B(i,j)-B(i,j-1));
        if(Defference>TS)
            I2(i,j-1)=255;           
        end        
         if((i<510)&&(i>498))
             I2(i,j-1)=255;
         end
      end
   end
   %% get a part of the image and show its RGB content in a graph.
   set(1,'color',[1 1 1]);
   title(['input 2 points,get a rectangular, show its RGB curve' num2str(1)]);
   % Use ginput to select corner points of a rectangular
   % region by pointing and clicking the mouse twice
   p = ginput(2); 
   % Get the x and y corner coordinates as integers
   sp(1) = min(floor(p(1)), floor(p(2))); %xmin
   sp(2) = min(floor(p(3)), floor(p(4))); %ymin
   sp(3) = max(ceil(p(1)), ceil(p(2)));   %xmax
   sp(4) = max(ceil(p(3)), ceil(p(4)));   %ymax
% Index into the original image to create the new image
MM = I(sp(2):sp(4), sp(1): sp(3),:);
% Display the subsetted image with appropriate axis ratio
figure(2); 
subplot(3,3,1);image(MM); axis image;title('the image extract');
hold on;
WW=40;
COnes=ones(WW);
CZeros=zeros(WW);
Mycolor=[0 0 0;0 0 1;0 1 0; 0 1 1; 1 0 0;1 0 1;1  1 0;1 1 1];
for i=1:8
    subplot(3,3,i+1);
    image(cat(3,Mycolor(i,1)*COnes,Mycolor(i,2)*COnes,Mycolor(i,3)*COnes));
    title(num2str(Mycolor(i,1))+num2str(Mycolor(i,2))+num2str(Mycolor(i,3)));
end
N=size(MM);
RowMax=min(8,N(1));
ColumnMax=min(900,N(2));
x=1:ColumnMax;
figure(3);
for i=1:RowMax 
    subplot(RowMax,1,i);
    y1=MM(i,1:ColumnMax,1);
    y2=MM(i,1:ColumnMax,2);
  y3=MM(i,1:ColumnMax,3);
  plot(x,y1,'r');
  hold on;
  plot(x,y2,'g');
  hold on;
  plot(x,y3,'b');
end
%% show the edge detection result in gray mode,edge is showed in red line.
  I4=cat(3,I2,I3,I3);
  figure(4);
  imshow(I4);

You can see in the background there are black lines seems like net. 'Rapid Shape Acquisition Using Color Structured Light and Multi-pass Dynamic Programming'.is the paper I based on.

This picture is I taken 2 days ago.My edge detection is totally failed. The key to success is to find each color transition through edge detection. But the line in background and the color cross talk is very serious!! Thank you very much.

It uses edge detection to find each color transition line.But it won't work well I guess.

  3 Comments

Hi John, I am currently also working on a similar project. Have you been able to solve the problem? Jaco

Hi Jaco,I am studying on how to generate a color stripe using De Bruijn sequence. But I don't konw how to start. Can u do me a favour? Dean

Hi John, I am currently also working on a similar project. Have you been able to solve the problem? Camilo

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