CODEWITHSUNDEEP
matlabimage-processing
onlyappleapp
onlyappleapp

Reputation: 21

Finding notes in an image

I have an image like this. And I want to find the location of notes. What is the best way to find them ? (They are not circle and they are so small so circlefinder can't find them !)

enter image description here

Image of Notes !

Upvotes: 1

Views: 149

Answers (1)

Benoit_11
Benoit_11

Reputation: 13945

Here is a bit of code to get you going...that's not perfect but it was a lof of fun haha.

What I did is to erode the image with a disk structuring element until what was left in the image was shapes the looked the most like circles. Then I eroded again but this time with a line structuring element oriented at an angle close to that of the notes; I figured it's about 15 degrees.

After that, call regionprops to get the centroids, and then plot them.

Code:

clear
clc

BW = im2bw(imread('Notes.png'));
BW = imclearborder(BW);

%//Erode the image with a disk structuring element to obtain circleish
%// shapes.
se = strel('disk',2);        
erodedBW = imerode(BW,se);

Here erodedBW looks like this:

enter image description here

%// Erode again with a line oriented at 15 degrees (to ~ match orientation of major axis of notes...very approximate haha) 

se2 = strel('line',5,15);
erodedBW2 = imerode(erodedBW,se2);

erodedBW2 looks like this:

enter image description here

Then find centroids and plot them

S = regionprops(erodedBW2,'Centroid');

figure;
imshow(BW)
hold on
for k = 1:numel(S)

   scatter(S(k).Centroid(:,1), S(k).Centroid(:,2),60,'filled')

end

Output:

enter image description here

Empty notes are not detected but that's manageable using other morphological operations I guess.

Hope that helps!

Upvotes: 6

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