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Draw Indian Flag using matlab
  • Last Updated : 20 Mar, 2019

In Digital image processing, a colored image is represented in a 3-Dimensional matrix. Image can be represented in various color models such as RGB (Red, Green, Blue) model, HSV (Hue, Saturation, Value) model, YIQ (Luminance-Inphase Quadrature) model, CMYK (Cyan, Magenta, Yellow, Black) model. Generally, an image is represented in the RGB model. The first channel of the matrix is Red, the second channel is the Green and the third channel is Blue.

Approach to draw Indian Flag

  • Firstly, we need to create a matrix of 300X600X3 and fill the matrix with white color. 300 is the number of rows and 600 is the number of columns. For color image 3 channels are required, so 3 represents RGB(Red Green Blue) channel.
    img=uint8(zeros(300, 600, 3))
  • Divide the matrix into three parts (0-100)rows for saffron color, (101-200)rows for white color and ashok chakra, (201-300)rows for green.
  • Fill the matrix with saffron color(255, 153, 51) from 1st row to 100th row.
    img(1:100, 1:600, 1)=255;
    img(1:100, 1:600, 2)=153;
    img(1:100;1:600, 3)=51;
    
  • Fill the matrix with green color(19, 136, 8) from row 201 to 300.
    img(201:300, 1:600, 1)=19;
    img(201:300, 1:600, 2)=136;
    img(201:300, 1:600, 3)=8;
    

  • To make ashok chakra, first we need to understand the equation of distance between two given coordinates.
    (distance)2=(x2-x1)2+(y2-y1)2

    (x1, y1) and (x2, y2) are the two given coordinates.

  • Using the above equation, we can make the circle of ashok chakra. Center coordinates of the matrix and circle is (150, 300). To draw cirle inner radius is 40 and outer radius is 45.




    for i=1:300
           for j=1:600
               if (sqrt(power(150-i, 2)+power(150-j, 2))>=40 &&
                   sqrt(power(150-i,2)+power(150-j,2))<=45)
                             img(i, j, 1)=0;
                             img(i, j, 2)=0;
                             img(i, j, 3)=128
               end
           end
         end

  • Angle between two adjacent spokes of ashok chakra is (360/n)=15o, where n(number of spokes)=24. atand is a MATLAB function used to find the angle.




    for i=110:190
        for j=260:340
            dist= (sqrt(power(i-150,2)+power(j-300,2)));
            k=round(atand((300-j)/(150-i)));
            if dist<=40 && mod(k,15)==0
                img(i,j,1:2)=0;
            end
        end
    end

Implementation is given below:






% MATLAB code to draw Indian flag
  
% initialising a zero matrix of 300X600X3
flag=uint8(zeros(300, 600, 3));
flag(:, :, :)=255;
%Saffron Color
flag(1:100, :, 1)=255;
flag(1:100, :, 2)=153;
flag(1:100, :, 3)=51;
  
%Green Color
flag(200:300, :, 1)=19;
flag(200:300, :, 2)=136;
flag(200:300, :, 3)=8;
  
%Ashok Chakra
for i=1:300
    for j=1:600
        if sqrt(power(i-150, 2)+ power(j-300, 2))>=40
            if sqrt(power(i-150, 2)+ power(j-300, 2))<=45
                flag(i, j, 1:2)=0;
            end
        end
    end 
end
for i=110:190
    for j=260:340
        dist= (sqrt(power(i-150, 2)+power(j-300, 2)));
        k=round(atand((300-j)/(150-i)));
        if dist<=40 && mod(k, 15)==0
            flag(i, j, 1:2)=0;
        end
    end
end
% displaying the matrix as image
figure, imshow(flag);

Output :

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