Image Blur using mean of nearby pixels

I have a problem function that Blurs image with the following output

output = blur(img,w);

where w is a parameter used for averaging. The output pixel value is the mean of the pixels in a square submatrix of size 2w+1 where the given pixel sits in the center.

After looking on the internet I tried this

im1 = imread(img);
kernel = ones(2*n+1)/(2*n+1)^2;
output = imfilter(im1,kernel);

but it gives errors

Error using imread>parse_inputs (line 502)

The file name or URL argument must be a character vector or string scalar.

Error in imread (line 342)

[source, fmt_s, extraArgs, was_cached_fmt_used] = parse_inputs(cached_fmt, varargin{:});

Error in blur (line 2)

rgbImage = imread(Y); % Sample image.

Honestly I don't even understand what it is saying.

Answer 1

[Shunichi Kusano]

The error comes from "imread". The function expects "The file name or URL argument" as input, but "img" seems not so. "img" can be used directly in imfilter in this case. please try:

output = imfilter(img,kernel);

hope his helps.

[Perturabo]

If I use

output = imfilter(img,kernel);

then what would be the purpose of

im1 = imread(img);

besides using this produced an error

Undefined function 'imfilter' for input arguments of type 'uint8'.

Error in blur (line 3)

output = imfilter(img,kernel);

[Shunichi Kusano]

I misunderstood what you want to do.

The function you made works. Note that "img" must be the filename of your image.

function output = blur(img, w);
im1 = imread(img);
kernel = ones(2*w+1)/(2*w+1)^2;
output = imfilter(im1,kernel);