Finding objects in images

I want to find objects with grayscale value <30. Now I am trying to write a table with all objects in excel file, then find and remove the row with a certain column value < 30, but there is always unexpected errors about my code.

 T = stats;
    excelfilename = 'Picture2.xlsx';
    writetable(T,excelfilename,'Sheet',1,'Range','A1');
    column=xlsread(excelfilename, 'A:A')
    H=length(column)

    for n = 1 : H
        MeanIntensity(n)= T(n,'MeanIntensity')
        if (MeanIntensity(n)<30)
            % Intensity is < 30
            mask = ismember(cc, n); 
            outputImage = I; 
            outputImage(~mask) = 0; 
            figure; % Bring up new figure
            imshow(outputImage , []);
        end
    end
The error is "You cannot subscript a table using linear indexing (one subscript) or multidimensional indexing (three or more subscripts). Use a row subscript and a variable subscript." The error refers to H which is shown in a correct number but stopped running the rest code. I also tried 'height' and 'size' of the table to denote H, but none worked. Does anyone know where is the problem in my code? Thank you for your time in advance.

Answer 1

[Image Analyst]

Maybe try braces T{n,'MeanIntensity'} instead of parentheses.

[Tian Tian]

Thank you so much! It worked perfectly!!