altering matrices

need some help for matrices ...

Your program should calculate new matrices where each point consists of the average of the surrounding 8 points and itself.

x11 x12 x13

x21 x22 x23

x31 x32 x33

The new value of x22 is the average of x11…x33. For simplicity, you do not need to calculate the average for the pixels on the edge. thanks

Answer 1

[Matt Tearle]

convn(A,B,'same')

where A is your matrix, and B is a mask that determines the weightings of points for averaging.

doc convn

for more details

[Sean de Wolski]

or conv2 for this case

[ben]

what would be the most effective way to get the B value??

[Matt Tearle]

ones (plus appropriate modifications)

[Sean de Wolski]

And to point you further in the right direction. What do you need to multiply 9 objects by before summing them to get their mean. Break down the definition of "mean".

[Matt Tearle]

8, not 9, if you're not including the middle point itself. BTW, think of that as a special case of a weighted average (with no weighting on x22)...

Answer 2

[Oleg Komarov]

If you have the Image Processing Toolbox use blockproc