How to draw multiple lines on a image and calculate the all length for multiple image?

How to draw multiple lines on a image and calculate the all length for multiple image?

[Walter Roberson]

is there a rule about where the lines should go?

[Nbillah]

Hi, just like the image .the vertical line only touch the surface/edge .It's better to draw line vertically for every pixel from the horizontal line. How I can run this with a loop?

[Walter Roberson]

What is the rule for where the horizontal line is to be placed?

Is it necessary to display the lines, or do you just want to know the distances?

[Image Analyst]

Are they drawn interactively be the user or do you just want the average height of the gap in the middle of your object? And how are you defining the "top" of the gap? Are you letting the user specify that or is there some rule as to where the "top" is?

Can you attach the original image without the blue lines and the white frame?

[Nbillah]

Actually I want to measure the variances of the height from the horizontal line. I attached my Image. Its better if I can do this something like the 2nd image as reference. They connect line for every pixel.

[Image Analyst]

This does not answer a single one of my questions.

[Walter Roberson]

Those white lines on the left and right: are they certain to be present on all of the images? How far below the lines do you want to take as the baseline?

I notice that the baseline is curved in the second image, so the measurement is not against a horizontal line.

[Nbillah]

Sorry, Please have a look the refernce 2nd image. the top line has rule like the red line (ignore my 1st image initially I posted) , the top line should be drawn from where the middle white line ends for both sides and then connect the two point . And I want to calculate the length for all heights.

[Image Analyst]

Why will you not attach your original image? Make it EASY for us to help you, not hard.

EDIT: Attached is one I created in Photoshop, though the original would have been better, and preferably not a crummy JPEG with it's super-low resolution.

[Nbillah]

I already attached my original image. your one is also right. I have 24 slices like this from one object.

[Image Analyst]

You did not attach the original image. You attached one with blue lines annotating it, and one with some other image stitched onto the right of it. See my answer below.

Answer 1

[Image Analyst]

Try this:

clc;    % Clear the command window.
clear all;
close all;  % Close all figures (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;

%===============================================================================
% Get the name of the image the user wants to use.
baseFileName = 'rnfl.png';
folder = pwd;
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
%=======================================================================================
% Read in demo image.
grayImage = imread(fullFileName);
% Get the dimensions of the image.
[rows, columns, numberOfColorChannels] = size(grayImage)
if numberOfColorChannels > 1
	grayImage = rgb2gray(grayImage);
end
% Display image.
subplot(2, 2, 1);
imshow(grayImage, []);
impixelinfo;
axis on;
caption = sprintf('Original Image\n%s', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0.05 1 0.95]);
% 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;

% Ask user to draw a line across the image.
message = sprintf('Draw the baseline across the gap.\nLeft click the left point.\nRight click the right point.');
text(5, 250, message, 'Color', 'r', 'FontSize', 16);
uiwait(msgbox(message));
[cx, cy, mask] = improfile();
hold on;
plot(cx, cy, 'r-', 'LineWidth', 2);

%===================================================================================
% Get a histogram
subplot(2, 2, 2);
imhist(grayImage);
grid on;
title('Histogram of gray scale image', 'FontSize', fontSize, 'Interpreter', 'None');

% Convert to binary
binaryImage = grayImage > 29;
% Display image.
subplot(2, 2, 3);
imshow(binaryImage, []);
impixelinfo;
axis on;
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;

% Take the 2 largest blobs.
binaryImage = bwareafilt(binaryImage, 2);
% % fill any small holes in lines (not sure if needed)
% binaryImage = imfill(binaryImage,'holes');
% Display image.
subplot(2, 2, 3);
imshow(binaryImage, []);
impixelinfo;
axis on;
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
% Draw line across binary image also.
hold on;
plot(cx, cy, 'r-', 'LineWidth', 2);

% For every cx, find the delta Y between cy and the top-most white pixel of the binary image.
deltaY = zeros(1, columns);
hold on;
for k = 1 : length(cx)
	thisX = round(cx(k));
	thisY = round(cy(k));
	% Extract column of binaryImage.
	thisColumn = binaryImage(:, thisX);
	topLineOfBinaryImage = find(thisColumn, 1, 'first');
	% Skip it if it's above the red line they drew.
	if topLineOfBinaryImage < thisY
		continue;
	end
	deltaY(thisX) = topLineOfBinaryImage - thisY;
	if rem(thisX, 5) == 0
		% Make blue line every 5 columns.  We still have deltaY for every column though.
		line([thisX, thisX], [thisY, topLineOfBinaryImage], 'Color', 'c');
	end
end
% Get the mean height.
meanHeight = mean(deltaY(deltaY>0))

% Display plot.
subplot(2, 2, 4);
plot(deltaY, 'b-', 'LineWidth', 2);
grid on;
message = sprintf('Delta Y vs. Column. The mean height = %f', meanHeight);
title(message, 'FontSize', fontSize, 'Interpreter', 'None');
xlabel('Column', 'FontSize', fontSize, 'Interpreter', 'None');
ylabel('Delta Y', 'FontSize', fontSize, 'Interpreter', 'None');

% Draw a line across the plot at the mean height.
hold on;
line(xlim, [meanHeight, meanHeight], 'color', 'r', 'LineWidth', 2);
message = sprintf('The mean height = %f', meanHeight);
uiwait(helpdlg(message));

[Nbillah]

Hi Image Analyst, thank you so much. The code is really helpful for me. You calculate the mean height. One question to ask, to see the variation of the length, should I calculate the variance of deltaY? And do the same process for all 24 slices, can I write like below?

baseFileName = dir(fullfile(F,'name*.png'))

Thank you again.

[Image Analyst]

Use var():

meanVariance = var(deltaY(deltaY>0))

Or std() if you want the standard deviation.

meanStDev = std(deltaY(deltaY>0))

To process a sequence of files, see the FAQ

Answer 2

[Nbillah]

Thank you Image Analyst for all codes and help. If you dont mind would you please delete the result image from your comment ? This works belongs to something confidential. And I dont know why the variance comes so high? Doesn't it calculate variance of the lengths only ?