How can I remove few parts of circle perimeter?

I have drawn few circles using plot function. How can remove few parts of circle perimeter? The concept is that circle perimter will be OFF when gets background and ON when gets image object.

[Adam]

Show how you drew them and it will be easier to advise. If you are using the plot function you must have defined your 'circle' as some finite number of segments so you could just plot the relevant segments instead of the whole circle.

[Zara Khan]

I have considered different radius to draw circles over the image .

[Adam Danz]

FYI, repeated question.

https://www.mathworks.com/matlabcentral/answers/449654-how-can-i-remove-few-parts-of-circle-perimeter?s_tid=prof_contriblnk

https://www.mathworks.com/matlabcentral/answers/447877-how-to-remove-few-part-of-a-circle?s_tid=prof_contriblnk

[Zara Khan]

yes I know.

[Image Analyst]

So did my answer below answer it or not?

[Zara Khan]

The code is great. Still I am unable to make them colors. Instead all are in black like the final image.

[Image Analyst]

You have a binary image. You said "off" which I take it to mean means "false" or black. If you want the lines to be colors, you need to use an RGB image and set the values in each color channel. Basically:

		rgbImage(row,col, 1) = redValue;
		rgbImage(row,col, 2) = greenValue;
		rgbImage(row,col, 3) = blueValue;

It should be easy for you to make that change. Let me know if it's too difficult for you and I'll do it.

[Zara Khan]

Image Analyst:

By 'off' I meant to say that only part will be removed. Circles will be in colors as it is. But parts which going through background will be removed only. It will look like the 'final image'. But instead of black will be the colors.

Sorry I was not able to explain it in a better way.

[Image Analyst]

To apply colors only to where the binary image was true (the hand), just check the binary image first before you assign the color to your RGB image:

if binaryImage(row, col)
	rgbImage(row,col, 1) = redValue;
	rgbImage(row,col, 2) = greenValue;
	rgbImage(row,col, 3) = blueValue;
end

Answer 1

[Image Analyst]

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;

rgbImage = imread('img.png');
% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(rgbImage)
if numberOfColorChannels > 1
	% It's not really gray scale like we expected - it's color.
	% Use weighted sum of ALL channels to create a gray scale image.
	% 		grayImage = rgb2gray(rgbImage);
	% ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
	% which in a typical snapshot will be the least noisy channel.
	grayImage = rgbImage(:, :, 2); % Take green channel.
else
	grayImage = rgbImage; % It's already gray scale.
end
% Now it's definitely gray scale with range of 0 to 255.

% Display the image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis('on', 'image');
hp = impixelinfo();

%------------------------------------------------------------------------------
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')
drawnow;

binaryImage = bwareafilt(~grayImage, 1);
props = regionprops(binaryImage,'Orientation','Centroid','MajorAxisLength','MinorAxisLength');
circleCenterX = props.Centroid(1);
circleCenterY = props.Centroid(2);

% Get the average of the min and max diameter.
diameter = mean([props.MajorAxisLength, props.MinorAxisLength], 2)

% Display the image.
subplot(2, 2, 2);
imshow(binaryImage);
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis('on', 'image');
hp = impixelinfo();
hold on
drawnow;
circumference = 2 * pi * props.MajorAxisLength;
t = linspace(0, 2*pi, 1.5 * circumference);
fprintf('Writing black to the %d points along the circles.', length(t));
for n = 1 : 8
	fprintf('Processing circle #%d.\n', n);
	r = n * diameter / 16;
	x = circleCenterX + r * sin(t);
	y = circleCenterY + r * cos(t);
	plot(x,y, 'LineWidth', 2);
	% Make the binary image black where it is at the circle.
	for k=1:length(x)
		col=round(x(k));
		row=round(y(k));
		binaryImage(row,col) = false;
	end
end
% Display the final image.
subplot(2, 2, 3);
imshow(binaryImage);
title('Final Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis('on', 'image');

Note: same code is also in your other question : Click for older question