The functions in GUI have error like the attached picture

GUI functions

Answer 1

[Geoff Hayes]

Shimaa - from your attached image, it is unclear what the error message might be (since you don't actually post it). The underlining of the popupmenu1_Callback looks more orange than red so this is most likely just a warning and not an error. The warning could be

 The function 'popupmenu1_Callback' might be unused.

This is a typical warning message in m files that have been created through GUIDE because there is no explicit call to this function anywhere from within your m file, rather it is associated with the control (the popup menu) which can be seen through the property inspector for that control.

If the above is indeed the warning message that you are observing, then it is safe to ignore it. (If you can't see the warning message, which should appear as a tool tip when you hover over the function name in the editor, right-click on the function name and select Open Message or Expand Details to get the full message.)

[Image Analyst]

I'd also switch on val rather than str{val} (unless there's a possibility that "image 1" and "image 2" might appear at different indexes from run to run, which is highly doubtful), and check to make sure that the (badly-named) "i" is not already a grayscale image (or else that will throw an error).