I am trying to sum the rows in an array of size 2048x2048 of 'unit8' data type.

Question

Steven Manz 2020-5-5

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/523187-i-am-trying-to-sum-the-rows-in-an-array-of-size-2048x2048-of-unit8-data-type

评论： Ameer Hamza 2020-5-6

0mm.bmp

In the code below, I take the image in the file attached at try to determine the space in which light is not frequent. Toward the bottom of the code at E = , the code sees an error. It says:

Index in position 1 is invalid. Array indices must be positive integers or logical

values.

Error in matlab_ex (line 77)

E = sum(raw_image,2);

Yet, when the same exact line is executed at B =, it runs perfectly. Could there be a reason for this?

clear all;
% change to desired path
path = 'C:\Users\steven.manz\Documents\Shaky Experiment 05_04_2020\distance_experiment\';
res_x = 2048; res_y = 2048; % resolution
A = double(raw_image);
B = sum(raw_image,1);
sum = 0;
for i = 1025:2048
    if B(1,i) < 50
        sum = sum + 1;
%         disp(sum)
    end
end
C = find(B<50);
D = C(1, [37:96]);
fprintf('The number of columns on the right half plane \n in which light seen is under threshold is %.1f\n\n',sum)
fprintf('Which happens at\n')
fprintf('column: %d\n',D)
sum = 0;
for i = 1:1024
    if B(1,i) < 50
        sum = sum + 1;
%         disp(sum)
    end
end
D = C(1, [1:36]);
fprintf('The number of columns on the right half plane \n in which light seen is under threshold is %.1f\n\n',sum)
fprintf('Which happens at\n')
fprintf('column: %d\n',D)
E = sum(raw_image,2);
sum = 0;
for i = 1025:2048
    if E(1,i) < 50
        sum = sum + 1;
%         disp(sum)
    end
end
C = find(E<50);
D = C(1, [37:96]);
fprintf('The number of columns on the top half plane \n in which light seen is under threshold is %.1f',sum)
fprintf('Which happens at\n')
fprintf('column: %d\n',D)
% sum = 0;
% for i = 1025:2048
%     if B(1,i) < 50
%         sum = sum + 1;
%         disp(sum)
%     end
% end
% 
% fprintf('The number of columns on the bottom half plane \n in which light seen is under threshold is %.1f',sum)

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Answer 1

Ameer Hamza 2020-5-5

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/523187-i-am-trying-to-sum-the-rows-in-an-array-of-size-2048x2048-of-unit8-data-type#answer_430480

编辑：Ameer Hamza 2020-5-5

在 MATLAB Online 中打开

You have defined a variable named 'sum' here

sum = 0; % <====== change its name here and everywhere else
for i = 1025:2048
    if B(1,i) < 50
        sum = sum + 1;
%         disp(sum)
    end
end

Therefore, in line

sum(raw_image,2)

MATLAB thinks you are referring to the variable named sum, not the function sum(). Change the name of variable to something else and make the replacement everywhere in the code.