Index in position 2 exceeds array bounds (must not exceed 320).

How do I fix this error? The error is occuring in line 24 ( the line below case "Inside" ). I am confused because the values of i and j should shouldn't ever exceed the array size because they are derived from the array. Can somebody please explain the issue. One of the errors that I thought could be occuring is that the local function in my code is not correctly identifing the positions of those indicies, but I check my function over with my friend and his works just fine.

myImage_color = imread("sunflower.jpg");
myImage_grayscale = rgb2gray(myImage_color);

% finds size of image
[row, col] = size(myImage_grayscale);
myImage_blur = zeros(row,col);

for i = 1 : row
    for j = 1 : col
        % calculates position of image
        position = IndexLocation(i,j, row, col);
        
        % blurs each pixel depending on position
        switch position
            case "INSIDE"
                    myImage_blur(i,j) =  ( myImage_grayscale(i,j+1) ...
                    + myImage_grayscale(i,j-1) + myImage_grayscale(i,j) ...
                    + myImage_grayscale(i-1,j-1) + myImage_grayscale(i-1,j) ...
                    + myImage_grayscale(i-1,j+1) + myImage_grayscale(i+1,j-1) ...
                    + myImage_grayscale(i+1,j) + myImage_grayscale(i+1,j+1) ) * (1/9) 
            case "NE"
                myImage_blur(i,j) = ( myImage_grayscale(i+1,j) ...
                    + 3 * myImage_grayscale(i,j) + myImage_grayscale(i,j-1) ...
                    + myImage_grayscale(i+1,j-1) ) * (1/6) ;
            case "RIGHT"
                myImage_blur(i,j) = ( myImage_grayscale(i+1,j) ...
                    + myImage_grayscale(i-1,j) + myImage_grayscale(i,j-1) ...
                    + 2 * myImage_grayscale(i,j) + myImage_grayscale(i+1,j-1) ...
                    + myImage_grayscale(i-1,j-1) ) * (1/7) ;
            otherwise
                myImage_blur = otherNodes(myImage_grayscale, i, j, position);
        end
        
    end
end

% displays grayscale and blurred image
imshow(myImage_grayscale)
imshow(myImage_blur)

% calculates position of pixel based on indicies
function [position] = IndexLocation(i,j, row, col)
    
    if i == 1 & j ~= 1 & j ~= col
        position = "LEFT";
    elseif i == row & j ~= 1 & j ~= col
        position = "RIGHT";
    elseif j == 1 & i ~= 1 & i ~= row
        position = "TOP";
    elseif j == col & i ~= 1 & i ~= row
        position = "BOTTOM";
    elseif i == 1 & j == 1
        position = "NW";
    elseif i == 1 & j == row
        position = "NE";
    elseif i == row & j == 1
        position = "SW";
    elseif i == row & j == col
        position = "SE";
    else
        position = "INSIDE";
    end
    
end

[Tommy]

My guess is

myImage_grayscale(i,j+1)

throws the error when j equals col.

[Jiawei Gong]

Thanks for the hint : )

Answer 1

[Bhargavi Maganuru]

myImage_grayscale(i+1, j+1) %causes error when i=row or j=col. 
myImage_grayscale(i-1, j-1) %causes error when i=1 or j=1. 

You could make changes accordingly.

Answer 2

[Image Analyst]

Change the lines to not go within half a window width of the edge. Your filter window is 3-by-3 so half the width is 1 and you should start at pixel 2, not pixel 1:

myImage_blur = myImage_grayscale; % Not zeros.
for i = 2 : row-1
    for j = 2 : col-1