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

1 次查看（过去 30 天）
sali
sali 2018-10-6
编辑： sali 2018-10-7
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
  6 个评论
显示 4更早的评论
sali
sali 2018-10-6
Thanks John for your answer I'll try this as well and see. Thanks Image Analyst for the answer , what I meant is reducing the line width to be one pixel before processing.
Image Analyst
Image Analyst 2018-10-7
Then you'll want to use
skelImage = bwmorph(binaryImage, 'skel', inf);
See my answer below for a full demo with your image.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Image Analyst
Image Analyst 2018-10-7
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);
uiwait(warndlg(errorMessage));
return;
end
end
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.
else
grayImage = rgbImage; % It's already gray scale.
end
% 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')
drawnow;
% 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');
  2 个评论
sali
sali 2018-10-7
Thanks I tried the code and it works, so what I understood that my image is not already black and white it is considered as RGB, so first it should be converted to grey scale then to binary img which is black and white, Am I right?
sali
sali 2018-10-7
编辑：sali 2018-10-7
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 )
imageData(i,j)=1;
else if ( imageData(i,j)==1)
imageData(i,j)=-1;
end
end
end
end

请先登录，再进行评论。

更多回答（1 个）

Matt J
Matt J 2018-10-6
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
bwmorph(BW,'skel',inf)
  5 个评论
显示 3更早的评论
sali
sali 2018-10-7
编辑：sali 2018-10-7
Do you mean this piece of code is right except the variable name which should not be “image”?
Image Analyst
Image Analyst 2018-10-7
No, there are still things wrong with it even if you fixed that. See my code below for a correct version.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Image Processing Toolbox 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by