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NA for the given answers.

Asked by simple_student on 18 May 2018 at 12:59
Latest activity Closed by simple_student on 21 May 2018 at 14:09

I think the question asked and answers are not very relevant. The question will be asked in an appropriate place.

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2 Answers

Answer by KALYAN ACHARJYA on 18 May 2018 at 13:17
Edited by KALYAN ACHARJYA on 19 May 2018 at 12:12
 Accepted Answer

%
clc;
clear all;
close all;
im=imread('01_dr.jpg'); %Give the image file name with proper format
input_image=im2bw(rgb2gray(im));
pos_1=[529,279]; %GIVEN
[rows colm]=size(input_image);
for i=1:rows
for j=1:colm
 if (input_image(i,j)==1)
    pos_2=[i,j];
    distance=sqrt((i-529)^2+(j-279)^2);
    end
  end
end 
d=max(distance);
fprintf('#The Max Distance is %i\n',d);
for i=1:rows
for j=1:colm
  if (input_image(i,j)==1)
     pos_2=[i,j];
     distance=sqrt((i-529)^2+(j-279)^2);
         if (distance==d)
           fprintf('#The Row Position %i\n',i);
           fprintf('#The Column Position %i\n',j);
           break;
         end
     end
   end
end 

  1 Comment

Hey, you want to find the distance between A and Tip, Am I right? And Tip Having white pixels, clarify?

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Answer by Image Analyst
on 19 May 2018 at 15:09

A simpler more direct way is to just background correct, threshold, and find the left most point and corresponding row number.

Try this (using attached images):

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;
% Check that user has the specified Toolbox installed and licensed.
hasLicenseForToolbox = license('test', 'image_toolbox');   % license('test','Statistics_toolbox'), license('test','Signal_toolbox')
if ~hasLicenseForToolbox
	% User does not have the toolbox installed, or if it is, there is no available license for it.
	% For example, there is a pool of 10 licenses and all 10 have been checked out by other people already.
	ver % List what toolboxes the user has licenses available for.
	message = sprintf('Sorry, but you do not seem to have the Image Processing Toolbox.\nDo you want to try to continue anyway?');
	reply = questdlg(message, 'Toolbox missing', 'Yes', 'No', 'Yes');
	if strcmpi(reply, 'No')
		% User said No, so exit.
		return;
	end
end
%===============================================================================
% Read in gray scale demo image.
folder = pwd; % Determine where demo folder is (works with all versions).
baseFileName = 'example_pipette.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);
% Display the image.
subplot(2, 3, 1);
imshow(rgbImage, []);
title('Original Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis on;
hp = impixelinfo();
% 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 blue 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 Gray Scale Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis on;
%------------------------------------------------------------------------------
% 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;
%------------------------------------------------------------------------------
% Read in background image.
[folder, baseFileNameNoExt, ext] = fileparts(fullFileName);
fullFileName = fullfile(folder, [baseFileNameNoExt, '_background.png']);
backgroundImage = imread(fullFileName);
% Display the image.
subplot(2, 2, 2);
imshow(backgroundImage, []);
title('Background Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis on;
% Divide them
bgCorrectedImage = double(grayImage) ./ double(backgroundImage);
% Display the image.
subplot(2, 2, 3);
imshow(bgCorrectedImage, []);
title('Background Corrected Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis on;
hp = impixelinfo();
% Threshold at 0.4 to find dark edges.
binaryImage = bgCorrectedImage < 0.9;
% Display the image.
subplot(2, 2, 4);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis on;
hp = impixelinfo();
% Find the left most columns
[rows, columns] = find(binaryImage);
[leftColumnX, indexOfLeft] = min(columns)
% Find the corresponding line/row/Y point
leftRowY = rows(indexOfLeft)
caption = sprintf('Binary Image. The tip is at column %d, row %d.', leftColumnX, leftRowY);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
% Place crosshairs there
hold on;
plot(leftColumnX, leftRowY, 'r+','MarkerSize', 200);
message = sprintf('The tip is at column %d, row %d.', leftColumnX, leftRowY);
uiwait(helpdlg(message));

  4 Comments

Show 1 older comment
Image Analyst
on 20 May 2018 at 12:54

Why is the background so dramatically different than with the pipette in place? Also, this pipette is a very different shape - why?

Image Analyst
on 20 May 2018 at 14:54

I think you just need to do

% Find the corresponding line/row/Y point
[rightColumnX, indexOfRight] = max(columns)
rightRowY = rows(indexOfRight)

And of course you need to see if you can get better control over your background. It's easier to process a good image than to try to fix up a bad image. If you can't you can try to use adapthisteq() on the original image, and not use a separate background image. adapthisteq() does a decent job of flattening the background.

Image Analyst
on 20 May 2018 at 22:25

You can process a batch of files with one of the two snippets in the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

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