Counting Australian coins in matlab

Hi, I need to write a function that calculates how many coins are in a picture and determines there combined value, I have the following code that works for a stock image, but I cant seem to apply it to work with an image containing Australian coins, such as this:

Here is the current code I have:

_______________________________________________________
coin1 = im2bw(imread('coins.png'));
coin2 = imfill(coin1,'holes');
[L Ne]=bwlabel(double(coin2));
prop=regionprops(L,'Area','Centroid');
total=0;
imshow(imread('coins.png'));hold on
for n=1:size(prop,1)
  doll=prop(n).Centroid;
  X=doll(1);Y=doll(2);
  if prop(n).Area>2000
      text(X-10,Y,'$1') 
      total=total+1;
  else
      total=total+2;
      text(X-10,Y,'$2') 
  end
end
number = n
dollar = total
hold on
title(['Dollars: $',num2str(dollar),'  ', 'Number of coins:',num2str(n)])
_________________________________________________________________

Any help would be appreciated, thanks

Answer 1

[Image Analyst]

See my demo where I do the same thing with the US coins supplied in the standard MATLAB demo image: http://www.mathworks.com/matlabcentral/fileexchange/25157-image-segmentation-tutorial-blobsdemo I find 5 cent and ten cent coins. Of course from that point it's a simple matter to add up the value of the coins.

Just a quick glance looks like your code should work as long as there are only two type of coins and those with area more than 2000 all have the same value and those with area less than that all have the same value. What is not working?

[Jamil]

Thanks for the feedback, when I run the function with the image I provided I get the following result: http://postimg.org/image/6edm8t1if/

I've tried altering the areas but I'm unable to get it working.

[Image Analyst]

After the

prop=regionprops(

line, put this:

allAreas = [prop.Area]

Tell me what it reports for the areas.

And tell me how many coins types there are (I don't know what the heads and tails of the coins look like, or if there are old style designs and new designs, since I don't live in Australia), and how many coins of each type. What should the answer be?

[Jamil]

I tried adding that line and I got the error: Undefined variable "props" or function "props.Area".

There are 2 coin types, $1 (larger) and $2 (smaller).

The answer should look like this, i was able to generate this using my stock image. http://s7.postimg.org/lwuo2ytrv/stockanswer.jpg

[Image Analyst]

Use prop.Area.

[Jamil]

Im sorry I am fairly new to Matlab, its been a challenge getting this far! what do you mean use prop.Area?

[Image Analyst]

Use prop.Area, not props.Area. prop is returned from regionprops, not props.

[Jamil]

Oh ok, i dont see any points in the code where im using props.area, I changed the code to look like this:

          prop=regionprops(L,'Area','Centroid');

          allAreas = [prop.Area]

Yet i still get the same incorrect result from before, where numbers = 1 and dollars = $1, and there is a single $1 symbol in the centre of the image, i appreciate your help by the way, Im just not sure what I need to fix in the code

[Image Analyst]

What is the value of size(prop,1)? It should be the number of coins. What does the allAreas line spit out to the command window? Are the coins either bigger than 2000 or less than 2000 pixels?

[Image Analyst]

Try this, it was the best I could do in 5 minutes but it gets the job done:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures if you have the Image Processing Toolbox.
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 a standard MATLAB gray scale demo image.
folder = 'C:\Users\Mark\Documents\Temporary';
baseFileName = 'coins.jpg';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);

grayImage = imread(fullFileName);
[rows, columns, numberOfColorBands] = size(grayImage);
if numberOfColorBands > 1
  % It's not really gray scale like we expected - it's color.
  % Convert it to gray scale by taking only the green channel.
  grayImage = grayImage(:, :, 2); % Take green channel.
end

% Display the original gray scale image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 

% Let's compute and display the histogram.
[pixelCount, grayLevels] = imhist(grayImage);
subplot(2, 2, 2); 
bar(pixelCount);
grid on;
title('Histogram of original image', 'FontSize', fontSize);
xlim([0 grayLevels(end)]); % Scale x axis manually.

binaryImage = grayImage < 240
subplot(2, 2, 3); 
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize);

% Fill holes
binaryImage = bwconvhull(binaryImage, 'objects', 4);
subplot(2, 2, 4); 
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize);

% Get rid of particles smaller than 2000 pixels.
binaryImage = bwareaopen(binaryImage, 2000);

% Label image.
[LabeledImage, numberOfCoins]=bwlabel(binaryImage);
% Make measurements of centroid and area.
measurements = regionprops(LabeledImage,'Area','Centroid');
% Print out areas.
allAreas = [measurements.Area]
total=0;
hold on
% Loop through, counting and labeling coins.
for n=1:size(measurements,1)
  centroid = measurements(n).Centroid;
  X=centroid(1);
  Y=centroid(2);
  if measurements(n).Area > 3000
    text(X-10,Y,'$1')
    total=total+1;
  else
    total=total+2;
    text(X-10,Y,'$2')
  end
end
number = n
dollar = total
hold on
title(['Dollars: $',num2str(dollar),'  ', 'Number of coins:',num2str(n)],...
  'FontSize', fontSize)

[Jamil]

Im not sure, I assume the coins are less than 2000 pixels, but then i cant imagine why it worked fine for my stock image, sorry like i said im new to matlab and im multitasking this task with a bunch of others, ive found this to be very confusing im not sure what i need to change in the code

[Jamil]

Wow thats awesome, thank you so much for your help, I'll read through that code and adapt it to my task, thanks again!