Berikut ini merupakan contoh aplikasi pemrograman GUI Matlab untuk mendeteksi warna dan bentuk suatu objek pada citra digital.

Proses deteksi warna diawali dengan mengkonversi ruang warna citra RGB (Red, Green, Blue) menjadi HSV (Hue, Saturation, Value). Selanjutnya proses klasifikasi warna dilakukan berdasarkan pengelompokan nilai Hue.

Sedangkan proses deteksi bentuk diawali dengan mengkonversi ruang warna citra RGB menjadi grayscale. Setelah itu dilakukan thresholding sehingga diperoleh citra biner. Kemudian dilakukan ekstraksi ciri morfologi dari citra biner berdasarkan parameter eccentricity dan metric. Proses klasifikasi citra dilakukan berbasis aturan (rule based) sederhana.

1. Membuka tampilan GUI awal

2. Membaca citra asli

3. Mendeteksi obyek dengan warna merah

4. Mendeteksi obyek dengan warna orange/jingga

5. Mendeteksi obyek dengan warna hijau

6. Mendeteksi obyek dengan warna biru

7. Mendeteksi obyek dengan warna ungu

8. Mendeteksi obyek dengan warna kuning

9. Mendeteksi obyek dengan bentuk polygon (segi banyak)

10. Mendeteksi obyek dengan bentuk segi-tiga

11. Mendeteksi obyek dengan bentuk kotak

12. Mendeteksi obyek dengan bentuk lingkaran

File source code lengkap beserta citra untuk mendeteksi warna dan bentuk dapat diperoleh melalui halaman berikut ini: Source Code

Sedangkan tampilan kodingnya adalah:

function varargout = Color_and_Shape_Detection(varargin)
% COLOR_AND_SHAPE_DETECTION MATLAB code for Color_and_Shape_Detection.fig
%      COLOR_AND_SHAPE_DETECTION, by itself, creates a new COLOR_AND_SHAPE_DETECTION or raises the existing
%      singleton*.
%
%      H = COLOR_AND_SHAPE_DETECTION returns the handle to a new COLOR_AND_SHAPE_DETECTION or the handle to
%      the existing singleton*.
%
%      COLOR_AND_SHAPE_DETECTION('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in COLOR_AND_SHAPE_DETECTION.M with the given input arguments.
%
%      COLOR_AND_SHAPE_DETECTION('Property','Value',...) creates a new COLOR_AND_SHAPE_DETECTION or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before Color_and_Shape_Detection_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to Color_and_Shape_Detection_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help Color_and_Shape_Detection

% Last Modified by GUIDE v2.5 02-Jul-2016 01:44:03

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
    'gui_Singleton',  gui_Singleton, ...
    'gui_OpeningFcn', @Color_and_Shape_Detection_OpeningFcn, ...
    'gui_OutputFcn',  @Color_and_Shape_Detection_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
% End initialization code - DO NOT EDIT


% --- Executes just before Color_and_Shape_Detection is made visible.
function Color_and_Shape_Detection_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to Color_and_Shape_Detection (see VARARGIN)

% Choose default command line output for Color_and_Shape_Detection
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);
movegui(hObject,'center');

% UIWAIT makes Color_and_Shape_Detection wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = Color_and_Shape_Detection_OutputFcn(hObject, eventdata, handles)
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;


% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
[filename,pathname] = uigetfile('*.jpg');

if ~isequal(filename,0)
    Img = imread(fullfile(pathname,filename));
    axes(handles.axes1)
    imshow(Img)
    title('Original Image');
    
    % Color Detection
    [m,n,~] = size(Img);
    hsv = rgb2hsv(Img);
    
    H = hsv(:,:,1);
    
    for y = 1:m
        for x = 1:n
            h = H(y,x);
            
            % Ubah warna
            if h < 11/255       % merah
                h = 0;
            elseif h < 32/255   % jingga
                h = 21/255;
            elseif h < 54/255   % kuning
                h = 43/255;
            elseif h < 116/255  % hijau
                h = 85/255;
            elseif h < 141/255  % cyan
                h = 128/255;
            elseif h < 185/255  % biru
                h = 170/255;
            elseif h < 202/255  % ungu
                h = 191/255;
            elseif h < 223/255  % magenta
                h = 213/255;
            elseif h < 244/255  % merah muda
                h = 234/255;
            else
                h = 0;          % merah
            end
            
            % Ubah komponen H
            H(y,x) = h;
        end
    end
    
    % Shape Detection
    gray = rgb2gray(Img);
    threshold = .8;
    bw = ~im2bw(gray,threshold);
    bw = imfill(bw,'holes');
    
    [B,L] = bwboundaries(bw,'noholes');
    stats = regionprops(L,'All');
    
    class = zeros(length(B),1);
    
    for k = 1:length(B)
        boundary = B{k};
        delta_sq = diff(boundary).^2;
        perimeter = sum(sqrt(sum(delta_sq,2)));
        area = stats(k).Area;
        eccentricity = stats(k).Eccentricity;
        metric = 4*pi*area/perimeter^2;
        
        if metric<0.56
            class(k,1) = 1;
        elseif metric<0.89
            if eccentricity>0.04 && eccentricity <0.05
                class(k,1) = 2;
            else
                class(k,1) = 3;
            end
        else
            class(k,1) = 4;
        end
        
    end
    
    handles.Img = Img;
    handles.H = H;
    handles.class = class;
    handles.bw = bw;
    guidata(hObject, handles)
    set(handles.pushbutton2,'Enable','on')
    set(handles.pushbutton3,'Enable','on')
    set(handles.pushbutton4,'Enable','on')
    set(handles.pushbutton5,'Enable','on')
    set(handles.pushbutton6,'Enable','on')
    set(handles.pushbutton7,'Enable','on')
    set(handles.pushbutton8,'Enable','on')
    set(handles.pushbutton9,'Enable','on')
    set(handles.pushbutton10,'Enable','on')
    set(handles.pushbutton11,'Enable','on')
else
    return
end

% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
H = handles.H;

H_aksen = H==0/255;
H_aksen = logical(H_aksen);

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~H_aksen) = 255;
G(~H_aksen) = 255;
B(~H_aksen) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Color Detection -> Red')

% --- Executes on button press in pushbutton3.
function pushbutton3_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton3 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
H = handles.H;

H_aksen = H==21/255;
H_aksen = logical(H_aksen);

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~H_aksen) = 255;
G(~H_aksen) = 255;
B(~H_aksen) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Color Detection -> Orange')


% --- Executes on button press in pushbutton4.
function pushbutton4_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton4 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
H = handles.H;

H_aksen = H==85/255;
H_aksen = logical(H_aksen);

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~H_aksen) = 255;
G(~H_aksen) = 255;
B(~H_aksen) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Color Detection -> Green')


% --- Executes on button press in pushbutton5.
function pushbutton5_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton5 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
H = handles.H;

H_aksen = H==170/255;
H_aksen = logical(H_aksen);

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~H_aksen) = 255;
G(~H_aksen) = 255;
B(~H_aksen) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Color Detection -> Blue')


% --- Executes on button press in pushbutton6.
function pushbutton6_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton6 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
H = handles.H;

H_aksen = H==213/255;
H_aksen = logical(H_aksen);

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~H_aksen) = 255;
G(~H_aksen) = 255;
B(~H_aksen) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Color Detection -> Purple')


% --- Executes on button press in pushbutton7.
function pushbutton7_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton7 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
H = handles.H;

H_aksen = H==43/255;
H_aksen = logical(H_aksen);

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~H_aksen) = 255;
G(~H_aksen) = 255;
B(~H_aksen) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Color Detection -> Yellow')


% --- Executes on button press in pushbutton8.
function pushbutton8_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton8 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
bw = handles.bw;
class = handles.class;

bw2 = false(size(bw));
n = find(class==1);
for x = 1:numel(n)
    cc = bwconncomp(bw, 4);
    bw2(cc.PixelIdxList{n(x)}) = true;
end

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~bw2) = 255;
G(~bw2) = 255;
B(~bw2) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Shape Detection -> Polygon')


% --- Executes on button press in pushbutton9.
function pushbutton9_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton9 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
bw = handles.bw;
class = handles.class;

bw2 = false(size(bw));
n = find(class==2);
for x = 1:numel(n)
    cc = bwconncomp(bw, 4);
    bw2(cc.PixelIdxList{n(x)}) = true;
end

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~bw2) = 255;
G(~bw2) = 255;
B(~bw2) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Shape Detection -> Triangle')


% --- Executes on button press in pushbutton10.
function pushbutton10_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton10 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
bw = handles.bw;
class = handles.class;

bw2 = false(size(bw));
n = find(class==3);
for x = 1:numel(n)
    cc = bwconncomp(bw, 4);
    bw2(cc.PixelIdxList{n(x)}) = true;
end

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~bw2) = 255;
G(~bw2) = 255;
B(~bw2) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Shape Detection -> Square')


% --- Executes on button press in pushbutton11.
function pushbutton11_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton11 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
Img = handles.Img;
bw = handles.bw;
class = handles.class;

bw2 = false(size(bw));
n = find(class==4);
for x = 1:numel(n)
    cc = bwconncomp(bw, 4);
    bw2(cc.PixelIdxList{n(x)}) = true;
end

R = Img(:,:,1);
G = Img(:,:,2);
B = Img(:,:,3);

R(~bw2) = 255;
G(~bw2) = 255;
B(~bw2) = 255;

RGB = cat(3,R,G,B);

axes(handles.axes2)
imshow(RGB);
title('Shape Detection -> Circle')


% --- Executes on button press in pushbutton12.
function pushbutton12_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton12 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
axes(handles.axes1)
cla reset
set(gca,'XTick',[])
set(gca,'YTick',[])

axes(handles.axes2)
cla reset
set(gca,'XTick',[])
set(gca,'YTick',[])

set(handles.pushbutton2,'Enable','off')
set(handles.pushbutton3,'Enable','off')
set(handles.pushbutton4,'Enable','off')
set(handles.pushbutton5,'Enable','off')
set(handles.pushbutton6,'Enable','off')
set(handles.pushbutton7,'Enable','off')
set(handles.pushbutton8,'Enable','off')
set(handles.pushbutton9,'Enable','off')
set(handles.pushbutton10,'Enable','off')
set(handles.pushbutton11,'Enable','off')