Compute average of each value in a matrix without using for

Hi all,

I was wondering is it possible to alter each value of a matrix based on the average value of its neighbors, wihtout using for loops?

Thanks in advance.

[the cyclist]

It would eliminate a lot of guesswork on the part of people trying to help you if you could be much more specific about what you want to do, and ideally provide at least one example of the input and output you would expect from this.

[Raldi]

You are right...

Well basicaly lets say i have

x= [0 0 0 0 0 0 0 2 0 0 0 0 0 1 0 0 0 0 0 0]

What i want is to create a new matrix that will be

newx= [0 0 (2/9) 0 0 0 0 2 0 0 0 0 (3/9) 1 0 0 0 0 0 0]

Here i randomly changed only two values to show that the get the average value of all the neighboring values.

Answer 1

[Honglei Chen]

you can use conv2 or imfilter, for example

x = magic(3)
y = conv2(ones(3)/9,x)

[Raldi]

Thanks...

[Matt J]

You can do this slightly more efficiently by taking advantage of separability

 h=ones(3,1)/3;
 y=conv2(x,h,h);

[Andrei Bobrov]

may be

y=conv2(h,h,x);

[Matt J]

Yes, that's what I really meant.

[Raldi]

Thanks alot guys.