'Undefined function or variable ' error but variable is defined in function working in GUI

So I have another problem with GUI. Like I said, I've perfectly working code but when I tried to get it into GUI I get this error:

Undefined function or variable 'h'.

Error in untitled>FILT_IMG_Callback (line 105)
    f=(h-1)/2;    % padding value for window: f=1; f=2; f=3; f=4; f=5;

Error in gui_mainfcn (line 95)
        feval(varargin{:});

Error in untitled (line 42)
    gui_mainfcn(gui_State, varargin{:});

I don't understand why I'm getting this error because variable is already defined. Here's code:

function FILT_IMG_Callback(hObject, eventdata, handles)
% hObject    handle to FILT_IMG (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
X = getappdata(0,'X');
A = rgb2gray (X);
X = A;
%setappdata(0,'filename',X);
%axes(handles.axes1);
%imshow(X);
if nargin < 2
    h=3;    % local search window size: h=3; h=5; h=7; h=9; h=11;
    f=1;    % padding value for window: f=1; f=2; f=3; f=4; f=5;
else
    f=(h-1)/2;    % padding value for window: f=1; f=2; f=3; f=4; f=5;
end
F = zeros(h*h,1);
Y  = zeros(size(X));

X = double(padarray(X,[f f],'symmetric'));
[m n ~] = size(X); 
%etc

Any ideas?

Answer 1

[Fangjun Jiang]

if nargin < 2
    h=3;    % local search window size: h=3; h=5; h=7; h=9; h=11;
    f=1;    % padding value for window: f=1; f=2; f=3; f=4; f=5;
else
    f=(h-1)/2;    % padding value for window: f=1; f=2; f=3; f=4; f=5;
end

if nargin>=2, then h is not defined.