Please help me in OMR

Question

Mark Jecel Rapir 2018-8-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/414150-please-help-me-in-omr

评论： Walter Roberson 2018-8-9

pic = dir('C:\Users\USER\Desktop\MMW\BSBA-01\*.jpg');
for a=1:length(pic);
    filename = strcat('C:\Users\USER\Desktop\MMW\BSBA-01\',pic(a).name);
I=rgb2gray(imread(filename));
options='ABCD'; % Options
ans=''; % This string stores the options entered by the student
key=' D C D C A D B A D B A A D D C A B C C C D A A A D D D A D D A A D A D D A D D A B C B B C C A C A A'; % This string contains correct answers
x=885; % x-coordinate of first bubble
y=770; % y-coordinate of first bubble
s=105; %spacing between each bubble
sr=95; %spacing between consecutive rows
for i=1:25                               
    sy=y+(i-1)*sr;
      for j=1:4          
      sx=x+(j-1)*s;
   %     disp(sx);
   %     disp(sy);
   %    disp(I(sy,sx));
      if((I(sy,sx)<25))        
          c(i,j)=0;
       else
          c(i,j)=1;    
      end
      end
  end

what does the 25 mean in this line?

if((I(sy,sx)<25))

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2018-8-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/414150-please-help-me-in-omr#answer_332091

It looks arbitrary to me. It looks like you are doing optical mark reading, and that that statement is detecting whether a particular location on the card is sufficiently dark to be considered filled in. Dark pixels have low uint8 values.

2 个评论
显示无隐藏无

Mark Jecel Rapir 2018-8-9

thank you. YEs Im working on OMR.

what does I(sx,sy) give? is it the number of pixel? if so, how can I determine the number of pixels?

Walter Roberson 2018-8-9

It is not the number of pixels, it is the intensity associated with the pixel located in row given by sx, column given by sy.

This is, by the way, a bit misleading. MATLAB arrays are indexed with y as the first coordinate, x as the second coordinate: the row is considered to be how far up or down you are (corresponding to y) and the column is how far left or right you are (corresponding to x).

请先登录，再进行评论。