MSE=immse(J,Kmedian)

when I type the command to calculate MSE i get the error statement Undefined function 'immse' for input arguments of type 'uint8'.

Answer 1

[Star Strider]

The immse function was introduced in R2014b.

If you have R2014b or later:

Type ver in the Command Window to see if you have the Image Processing Toolbox installed.

If you do, then enter these two lines in the Command Window:

restoredefaultpath 
rehash toolboxcache

and try again.

If you are still not able to use the function, Contact Support (link).