How to make function to call the stack of four images in matlab ?

Hello,

I am working on a project Differential phase contrast imaging, I have a code to do the same, but the problem I am unable to find the solution is to call the Ih function into the main code.

I do not know how to create function in matlab for the stack of four images . So if anyone could help me to create the Ih function into the matlab in my code then it would be very helpful to me.

what Ih is ?

Ih is stack of four images. Images I have to use when code call Ih function in main code.

I have all other function which are used in the code. I have attached the code.