error: Index exceeds the number of array elements (1).

close all;
workspace;
vid= VideoReader('sony.mp4');
F= vid.NumFrames;
sum=0;
for i=1:F
    video = read (vid,i);
    [rows , columns ]= size (video(i));
    noisyvideo(i)= imnoise(video(i),"gaussian",0,0.02);
    squareErrorFrame(i) = (double(noisyvideo(i))-double(video(i))).^2;
    MSE = sum(sum (squareErrorFrame(i)))/(rows*columns);
    sum= sum + MSE;
end
display(sum);

Index exceeds the number of array elements (1).

Error in forloopTrail (line 11)

MSE = sum(sum (squareErrorFrame(i)))/(rows*columns);

Answer 1

[Jan]

Do not use the name "sum" for a variable. Avterwards the function with the same name is shadowed:

clear sum
sum(1:10)    % working
sum = 0
sum(1:10)    % failing

So simply rename your variable "sum":

sumMSE = 0;
...
    sumMSE = sumMSE + MSE;

If your code is a script, "sum" has been shadowed in the base workspace. Then clean it up by:

clear sum

A general hint: Use functions instead of scripts, such that shadowed functions do not have unexpected effects in other scripts, where they are extremly confusing. Shadowing important built-in function is a frequent problem, so avoid this as good as possible.

Are you sure, that this is wanted:

    [rows , columns] = size(video(i));
    %                            ^^^ ?!    

With

    noisyvideo(i) = imnoise(video(i),"gaussian",0,0.02);    

the array noisyvideo is growing in each iteration. The editor should show you a hint. This is extremly expensive. Example:

x = [];
for k = 1:1e6
   x(k) = k;
end

Although the resulting vector needs 8MB only (8 bytes per double), Matlab has to create a new vector in each iteration and copies the elements of the former ones. So in totel Matlab allocates sum(1:1e6)*8 bytes and copys almost the same amoubnt of memory: More than 4 Terabyte!

Solution: Either preallocate:

x = zeros(1, 1e6);  % Pre-allocate
for k = 1:1e6
   x(k) = k;
end

Or if you do not need all x, do not store them:

for k = 1:1e6
   x = k;
   ... something can be done with x here
end

In your case I guess using noisyvideo without (i) is sufficient.

[Sudha R Jogin]

solved my problem , Thank you.