Is the number of points in a line image equals the number of pixels?

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Dear all, Is there any matlab image operator or function that tell the matlab to process an image of line as a group of pixels in such each point in the line is expressed as one pixel? Thanks
Image Analyst
Image Analyst on 7 Oct 2018
Then you'll want to use
skelImage = bwmorph(binaryImage, 'skel', inf);
See my answer below for a full demo with your image.

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Accepted Answer

Image Analyst
Image Analyst on 7 Oct 2018
Try this full demo:
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;
% Read in gray scale demo image.
folder = pwd; % Determine where demo folder is (works with all versions).
baseFileName = 'image1.png';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
% The file doesn't exist -- didn't find it there in that folder.
% Check the entire search path (other folders) for the file by stripping off the folder.
fullFileNameOnSearchPath = baseFileName; % No path this time.
if ~exist(fullFileNameOnSearchPath, 'file')
% Still didn't find it. Alert user.
errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
rgbImage = imread(fullFileName);
% 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(:, :, 1); % Take red channel.
grayImage = rgbImage; % It's already gray scale.
% Now it's 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')
% Binarize the image
binaryImage = grayImage < 128;
% Display the image.
subplot(2, 2, 2);
imshow(binaryImage, []);
title('Initial Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis('on', 'image');
% Skeletonize the image.
skelImage = bwmorph(binaryImage, 'skel', inf);
% Display the image.
subplot(2, 2, 3);
imshow(skelImage, []);
title('Skeleton Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis('on', 'image');
sali on 7 Oct 2018
Edited: sali on 7 Oct 2018
I was using this piece of code (regardless of scaling the image) is this right? I want to have a black and white image and deal with the black as 1 and white as -1 then reverse result at the end of my code which is not included here for simplicity.
I = imread('image1.png');
level = graythresh(I);
BW = im2bw(I,level);
A = BW(1:100,1:100);
imageData = int8(A);
for i=1:100
for j=1:100
if(imageData(i,j)==0 )
else if ( imageData(i,j)==1)

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More Answers (1)

Matt J
Matt J on 6 Oct 2018
I think what you are asking is if there is a way to reduce the image of the lines to 1 pixel in width. If so, you can use bwskel or
Image Analyst
Image Analyst on 7 Oct 2018
No, there are still things wrong with it even if you fixed that. See my code below for a correct version.

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