MATLAB: Do I get “Array indices must be positive integers or logical values.” Image processing.

array indices must be positive integers or logical values.histogram analysisimage normalisationImage Processing Toolbox

Please help me. I dont know what I doing wrong…
clear all, clc 
    
    [Iwe, map] = imread('chest-xray_2','bmp');
    figure(1)
    image([Iwe,map]);
    title("oryginal image")
    
    colormap(map);
    Iwe=double(Iwe);
    [row col deep]=size(Iwe);
    
    IweR=Iwe(:,:,1);
    IweG=Iwe(:,:,2);
    IweB=Iwe(:,:,3);
    
    
    Iwe_grey(:,:,1)=(IweR+IweG+IweB)/3;
    Iwe_grey(:,:,2)=Iwe_grey(:,:,1);
    Iwe_grey(:,:,3)=Iwe_grey(:,:,1);
    Iwe_grey=Iwe_grey(:,:,1);
    
    figure(2)
    imshow(Iwe_grey);
    title("monochrome image");
    Iwe_grey=uint8(Iwe_grey);
    
    %%started histogram
    histogram = zeros(256,1);
    for y=1:col
        for x=1:row
         b=Iwe_grey(x,y)+1;
         histogram(b+1)=histogram(b+1)+1;
    
        end
    end
    
    figure(3)
    bar(histogram);
    %%stacked histogram
    cumulative(1)=histogram(1)
    for z=2:256
        cumulative(z)=cumulative(z-1)+histogram(z)
    end
    
    cumulative = cumulative'
    
    %%aligned histogram
    for z=1:256
            hist_norm(z) = (256*cumulative(z)/cumulative(256));
    end
    
    figure(4)
    plot(hist_norm);
    title('aligned histogram')
    
    for x=1:row
        for y= 1:col
            if(Iwe_grey(x,y)<0)
               Image_out_grey(x,y)=0;
            else if (Iwe_grey(y,x) > 255)
                else Image_out_grey(y,x)=255*cumulative(Iwe_grey(y,x))/cumulative(255);
                end;
            end;
        end;
    end;
    
    Image_out_grey = uint8(Image_out_grey);
    figure(5)
    imshow(Image_out_grey);
    title("the resulting image after aligning the histogram");

Best Answer

You get that error because any time you use indexing to extract values from a variable, the index number must be integers >= 1. Somewhere in your code (you did not indicate where) you are using an invalid index.
% Good
A=[1:10];
A(3)
ans = 3
% Bad
A(4.3)
Array indices must be positive integers or logical values.
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