How to declare static and global variable in MATLAB - matlab

Question

I am using a function of increase and decrease sharpness, contrast of an image but the problem is that I have to get the value of the increased or decreased sharpness or contrast value from the functions to reuse those values. the function of increase and decrease of sharpness or contrast happens when the button is clicked in the GUI. Kindly help me to use and declare static and global variables which will be used in the application.
Main GUI File
function varargout = Cotton_Disease_Detector(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name', mfilename, ...
'gui_Singleton', gui_Singleton, ...
'gui_OpeningFcn', #Cotton_Disease_Detector_OpeningFcn, ...
'gui_OutputFcn', #Cotton_Disease_Detector_OutputFcn, ...
'gui_LayoutFcn', [] , ...
'gui_Callback', []);
if nargin && ischar(varargin{1})
gui_State.gui_Callback = str2func(varargin{1});
end
if nargout
[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
gui_mainfcn(gui_State, varargin{:});
end
function Cotton_Disease_Detector_OpeningFcn(hObject, eventdata, handles, varargin)
axes(handles.axes1);
axis off
axes(handles.axes4);
axis off
axes(handles.axes5);
axis off
axes(handles.axes6);
axis off
handles.output = hObject;
guidata(hObject, handles);
function varargout = Cotton_Disease_Detector_OutputFcn(hObject, eventdata, handles)
varargout{1} = handles.output;
function browse_Callback(hObject, eventdata, handles)
image=browseImage();
imshow(image,'Parent',handles.axes1)
function segmentation_image_Callback(hObject, eventdata, handles)
image = imread('enhance.jpg');
image=imageSegmentation(image);
imshow(image,'Parent',handles.axes5);
function enhance_image_Callback(hObject, eventdata, handles)
image=imread('resize.jpg');
set(handles.enhancementPanel,'Visible','On')
image=imageEnhancement(image);
imwrite(image,'enhance.jpg');
imshow(image,'parent',handles.axes4);
function classification_image_Callback(hObject, eventdata, handles)
function feature_extraction_image_Callback(hObject, eventdata, handles)
function decreaseContrast_Callback(hObject, eventdata, handles)
image=imread('enhance.jpg');
[J,x]=decreaseContrast(image,x);
imwrite(J,'enhance.jpg');
imshow(J,'parent',handles.axes4);
function increaseContrast_Callback(hObject, eventdata, handles)
image=imread('enhance.jpg');
[J,x]=increaseContrast(image,x);
imwrite(J,'enhance.jpg');
imshow(J,'parent',handles.axes4);
function decreaseSharpness_Callback(hObject, eventdata, handles)
image=imread('enhance.jpg');
[J,x]=decreaseSharpness(image,x);
imwrite(J,'enhance.jpg');
imshow(J,'parent',handles.axes4);
function increaseSharpness_Callback(hObject, eventdata, handles)
image=imread('enhance.jpg');
[J,x]=increaseSharpness(image,x);
imwrite(J,'enhance.jpg');
imshow(J,'parent',handles.axes4);
function resizeImage_Callback(hObject, eventdata, handles)
image=imread('read.jpg');
image=resizeImage(image);
imwrite(image,'resize.jpg');
Function of increase Sharpness
function [image,x] = increaseSharpness(image,x)
if isempty(x)
x=0.2;
end
x=x+0.2;
image=imsharpen(image,'radius',2,'Amount',x);
end
Function of decrease Sharpness
function [image,x] = decreaseSharpness(image,x)
if isempty(x)
x=0.2;
end
x=x-0.2;
image=imsharpen(image,'radius',2,'Amount',x);
end
The functions of increase decrease Contrast are same as of Sharpness.

Answer 1

Rather than using globals, Matlab provides ways to store data directly on your GUI objects.
This page has a good overview of these methods.
The most appropriate way to share data between calls is to use setappdata(hObject, name, value) to store values on you GUI object and use getappdata(hObject, name) to retrieve them.
Another method is to use the guidata(hObject, data) function allowing you to store a single variable or struct. However, GUIDE GUI's use this function to store a handles object, so the setappdata method is preferred.
[EDIT based on comment from #Hoki]