Simple Image Thresholding using GUI component Slider

Thresholding is one of the steps performed on the image during image conversion. 
Also Learn: Otsu's thresholding method

It is used for separating the background from the foreground.

The user can drag the slider to adjust the Thresholding. The slider value ranges between 0 and 255.

MATLAB CODE:

function f=mainthresh()

%The window size of the image is adjusted based on the screen size.

global T1;

ssz = get(0,'ScreenSize');

figure('Visible','on','Name','IMAGE THRESHOLDING','NumberTitle','off','Position',ssz);

axes('units','pixels','Position',[ssz(3)/45 ssz(4)/4 ssz(3)-(ssz(3)/4) ssz(4)-(ssz(4)/3)]);

in=imread('coins.png');

imshow(in);

set(gca,'xtick',[],'ytick',[])

%The Slider is one of the GUI component in MATLAB. The Value of the slider is between 0 and 255.

%These values can be changed based on the image type.

slid=uicontrol('Style','Slider','Visible','on','Value',1,'Max',255,'Min',0,'Sliderstep',[1 1],'Position',[ssz(3)/35 ssz(4)/5 ssz(3)-(ssz(3)/3) 20],'Callback', @threshing_image);

ent=uicontrol('Style','pushbutton','Visible','on','String','THRESHOLD VALUE','Position',[ssz(3)-(ssz(3)/4) ssz(4)-(ssz(4)/8) 105 30]);

ed=uicontrol('Style','edit','Visible','on','String','0','Value',1,'Position',[ssz(3)-(ssz(3)/4) ssz(4)-(ssz(4)/6) 90 20]);

%When the slider is moved the corresponding position value is passed to the function 'threshing_image' .

%The original image is passed to another function 'Imthreshold'.

      function threshing_image(object,~)

        val=get(object,'value');

        in=imread('coins.png');

        T1=Imthreshold(in,val);

        imshow(T1);

        set(gca,'xtick',[],'ytick',[])

       

        set(ed,'String',val);

      end

    

%Based on the value passed, the image background is separated from the foreground.

%In this example, the background of the coins image contains pixel values less than 80.

%By adjusting the slider to value 80 the background area gets value zero and the coins appear as it is.

function Im=Imthreshold(Image,Tvalue)

%Replace the pixel value either with 0 or 255.

Image( find ( Image(:,:,1) < Tvalue ) )=255;

Im=Image;

end

f=T1;

end

Thresholded Image

Here is another example , This Image is RGB. So we have to consider the RED, GREEN and BLUE pixel values.