Question

Help with matlab please?

You are given an idealised test image with a single circular feature. You are to develop an algorithm and implement that algorithm in the form of a MATLAB program that is capable of performing the following tasks. Find the centre of the circular feature in pixels. Calculate the radius of the feature in pixels. 2. Calculate the area of the feature in pixels. 3. Task 1: Low Resolution Sensor Image 10 20 30 40 50 80 70 60 50 30 40 20 10 Column

Answer 1

The image is stored in the same directory as the file, under the name 'test.png'.

The required code, along with the description of the algorithm is given as under:

% Reeading up the image and preporcessing
% The image is firstly converted in grayscale. Then it is binarized so as
% to clearly separate out the circle from the image
img = imread('test.png');
img = rgb2gray(img);
[m,n] = size(img);
imshow(img);

imgb = zeros(m,n);
for i = 1:m
for j = 1:n
if img(i,j) > 100
imgb(i,j) = 255;
else
imgb(i,j) = 0;
end
end
end
imshow(imgb);

% The number of pixels in the circle is obtained, so as to find out the
% area of the circle

count = 0;
for i=1:m
for j=1:n
if imgb(i,j) == 255
count = count + 1;
end
end
end

dia = 0;
startx = 0;
starty = 0;
endx = 0;
endy = 0;

% The radius and the center is obtained by finding out the diameter line of
% the circle. Then its length is used to find out the radius, and the
% midpoint gives out the center of the circle.

for i=1:m
for j=2:n-1
if imgb(i,j) == 255 && imgb(i,j-1) == 0
startx = i;
starty = j;
end
if imgb(i,j) == 255 && imgb(i,j+1) == 0
endx = i;
endy = j;
end
end
x = endy - starty;
if x > dia
dia = x;
centerx = startx;
centery = (endy + starty)/2;
end
end
radius = dia/2;

% Display Data
fprintf('Center of Circle: (%.2f,%.2f)\n', centerx, centery);
fprintf('Radius of Circle: %.2f pixels\n', radius);
fprintf('Area of Circle: %.2f pixels\n', count);

======================================================================================

circle,m ×1+ % Reeading up the image and preporcessing % The image is firstly converted in grayscale. Then it is binarized so as % to clearly separate out the circle from the image imgimread( test.png); img-rgb2gray (img); [m,nsize(img); imshow (img); 2 imgb zeros (m, n); for i = 1:m for j -1:n if img (i,j) 12- 100 > imgb(i,j) -255; 13- else imgb (i,j) 15- = 0; 16- end end end 18- imshow(imgb); 19-1 20 % The number of pixels in the circle is obtained, so as to find out the area of the circle 21 count 0; for i=1 : m for j=1:n if imab (i,j) 27 - = 255 28 count = count + 1; end end 29 end 31 32 dia = 0; startx 0; starty = 0; endxo endy0; 37 - 38

% The radius and the center is obtained by finding out the diameter line of % the circle. Then its length is used to find out the radius, and the % midpoint gives out the center of the circle. 39 40 41 for i=1 : m for j-2:n-1 if imgb (i,j) = 255 &&imgb (1小1) 45- =0 46 - startx = 1; 47 - starty ]: end if imgb (i,j)- 255 && imgb(i,j+1)0 49 - 50 endX = 1 ; endy = J ; 51 - 52 - end 53 - end x -endy starty; if x > dia 55 - 56 - dia = x; 57 - centerx = startx; centery(endy starty)/2; end 58 - 59 - end radius dia/2; 61 62 % Display Data tprintf("center of Circle: (8.2f.*.2f)\n", centerx, tprintf ('Radius of Circle: %2t pixels\n", radius); tprintf ("Area of Circle : %.2f pixels\n", count); 63 centery); 64 65

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The screenshot of the code execution and the binarized image is given as under:

Figure 1 Command Window Eile Edit View Insert Iools Desktop Window Help »> circle Center of Circle: (174.00, 189.50) Radius of Circle: 8S.50 pixels Area of Circle: 24526.00 pixels