vertical axis is flipped

Question

Naema 2015-3-31

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/195500-vertical-axis-is-flipped

编辑： Naema 2015-4-2

Hi Matlab users: I am facing two strange problems. The first problem is with figure#1; it is inverted in y. The following code reads the .txt file ,which is attached, to be inverted in (y). I am wondering what could be wrong in my code that the data in the .txt file are inverted vertically. Second problem is with figure#4: Why the vertical axis is flipped in figure#4. The y axis shows the minus on top and the positive side on bottom. NOTE: this code produces the result in one minute, please run it and give me your comments.

clear all;
    close all;
    clc;
     x1=-2.5:1e-3:2.5;
            y1=-2.5:1e-3:2.5;
              step=30;   
              randomscannb=100;    
              lambda0=1.31;  
              rf=((2.25)/2); 
             [X1,Y1]=meshgrid(x1,y1);
             Ey2a4=exp((-X1.^2-Y1.^2)/rf^2);
              Ey1a4=dlmread('C:\Users\kgazz012\Desktop\March19th\ccccc_10t_10w_1nmstep.txt');
               Ey1a4c=conj(Ey1a4);
             sfinalmatrix=size(x1);sfinalmatrix=sfinalmatrix(2);
             figure(1);subplot(1,2,1);imagesc(real(Ey1a4));title('Ey1a4 real part')
                  axis square;
                  figure(2);subplot(1,2,1);imagesc([x1(1) x1(sfinalmatrix)],[y1(1) y1(sfinalmatrix)],real(Ey2a4));title('Ey2a4 real part');xlabel('um')
                  axis square;
                  figure(1);subplot(1,2,2);imagesc(imag(Ey1a4));title('Ey1a4 imag part')
                  axis square;
                  figure(2);subplot(1,2,2);imagesc([x1(1) x1(sfinalmatrix)],[y1(1) y1(sfinalmatrix)],imag(Ey2a4));title('Ey2a4 imag part');xlabel('um')
                  axis square;
                  fiberscan=Ey2a4+1;
                  selectedscan=round(rand(1,randomscannb)*(sfinalmatrix*sfinalmatrix)/(step^2));
                  match=0;
                  C=zeros(sfinalmatrix,sfinalmatrix);
              Norma = sum(sum(Ey2a4.*conj(Ey2a4)))*sum(sum(Ey1a4.*conj(Ey1a4)));
              c=0;
                tic
              for b=1:step:sfinalmatrix-300+1
                      for a=1:step:sfinalmatrix-248+1
                          c=c+1; 
                        display(strcat('fractionexecuted=',num2str(c*(step^2)/(sfinalmatrix*sfinalmatrix)))) 
                          fib=Ey2a4(b:b+300-1,a:a+248-1); 
                             fn=fib.*conj(Ey1a4); 
                          C(b+150,a+124)=sum(sum(fn))./sqrt(Norma); for k=1:randomscannb
                                      if c==selectedscan(k)
                                          match=1;
                                      end
                                  end
                                  if match==1
                                      fiberscan(b:b+300,a:a+5)=0;
                                      fiberscan(b:b+300,a+243:a+248)=0;
                                      fiberscan(b:b+5,a:a+248)=0;
                                      fiberscan(b+295:b+300,a:a+248)=0;
                                      match=0;
                                  end
                      end
                  end
                  toc
                  pack
                  result=abs(C);
          figure(100);imagesc([x1(1) x1(sfinalmatrix)],[y1(1) y1(sfinalmatrix)],real(fiberscan));title('Ey2a4 with 100 random scan positions indicated');xlabel('um')
      if step>1
                  resultx=real(result)*0;
                  for a=1:sfinalmatrix
                      for b=1:sfinalmatrix
                          if result(b,a)==0
                          elseif a>step+1 & b>step+1 & a<sfinalmatrix-step-1 & b<sfinalmatrix-step-1
                              hs=round(step/2);
                              resultx(b-hs:b+hs,a-hs:a+hs)=0*result(b-hs:b+hs,a-hs:a+hs)+result(b,a);
                          end
                      end
                  end
              else
                  resultx=(result);
              end
          figure(3);subplot(1,2,1);imagesc([x1(1) x1(sfinalmatrix)],[y1(1) y1(sfinalmatrix)],real(resultx));title('real part of overalp');xlabel('um')
          axis square;
          figure(3);subplot(1,2,2);imagesc([x1(1) x1(sfinalmatrix)],[y1(1) y1(sfinalmatrix)],imag(resultx));title('imaginary part of overlap');xlabel('um')
          axis square;

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Answer 1

Chad Greene 2015-3-31

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/195500-vertical-axis-is-flipped#answer_173480

在 MATLAB Online 中打开

Image axes are like that because image coordinates start at the top left corner if you're counting pixels. It's an old convention from image people, not from Matlab. Use

axis xy

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Naema 2015-4-1

ccccc_10t_10w_1nmstep.txt

here is the .txt file attached

Naema 2015-4-2

编辑：Naema 2015-4-2

should not I only flip the y-axis but not the result? When I use axis xy, it flips the y axis and the plotted result.Please, let me now what is the correct thing to do as the plotted result is unknown to be shifted up or down.

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