How to label coins after recognizing them?

Hi everyone! I hope everything is great.

I have a question about coin recognition. I'm new to image processing and I'm trying to recognize the coins, label them and calculate the total amount.

Here is my code;

img = imread('bp3.jpg');

I = rgb2gray(img);
imshow(I)
bw = imbinarize(I);
figure; imshow(bw)
bw = bwareaopen(bw, 400);
figure; imshow(bw)
se = strel('disk', 3);
bw = imclose(bw, se);
bw = imfill (bw, 'holes');
figure; imshow(bw);
[r, num] = bwlabel(bw);
prop = regionprops('table',bw,{'Area','centroid'});


% kurus5=0;
% kurus10=0;
% kurus25=0;
% kurus50=0;
% tl1=0;
total=0;

for i=1:num;
    switch logical(true)
        case prop.Area(i)> 1.4e+06
                rgb = insertText(I,[prop.Centroid(i,1) prop.Centroid(i,2)],'1tl','FontSize',48,'TextColor','black');
                total=total+1;
                %tl1=tl1+1;
        case prop.Area(i)>1.2e+06 && prop.Area(i)<1.4e+06
                rgb = insertText(I,[prop.Centroid(i,1) prop.Centroid(i,2)],'50kr','FontSize',48,'TextColor','black');
                total=total+0.5;
                %kurus50=kurus50+1;
        case prop.Area(i)>8.7e+05 && prop.Area(i)<1.2e+06
                rgb = insertText(I,[prop.Centroid(i,1) prop.Centroid(i,2)],'25kr','FontSize',48,'TextColor','black');
                total = total + 0.25;
                %kurus25=kurus25+1;
        case prop.Area(i)>6.4e05 && prop.Area(i)<8.7e05
                rgb = insertText(I,[prop.Centroid(i,1) prop.Centroid(i,2)],'10kr','FontSize',48,'TextColor','black');
                total = total + 0.10;
                %kurus10=kurus10+1;
        otherwise
                rgb = insertText(I,[prop.Centroid(i,1) prop.Centroid(i,2)],'5kr', 'FontSize',48,'TextColor','black');
                total = total + 0.05;
                %kurus5=kurus5+1;
        end
    end


 subplot; imshow(rgb)
 title(['Total Amount:',num2str(total),'TL'])

I can calculate the total amount but the problem is I can't label them all. Only one of the labels is shown. (It is 5kr for this example.) And let say if I delete '5kr' part, then only '10kr' label would shown. However I can't show them all at once.

I don't know how to fix that and I'd be glad if you can help me. Thanks in advance.

[Jan]

This is a really bad idea:

switch logical(true)    

On one hand, true is a logcial already, so casting it again is a waste of time. On the other hand, your code is working with the switched switch conditions, but this is at least confusing.

The case prop.Area(i)==1.4e+06 is unlikely, but not ibncluded in your code.

What is the purpose of the orphaned subplot; command?

[Aysenur Atagün]

Hi Jan!

Thank you very much for both your answer and comment. I fixed my code with your suggestions and now it works. I used logical(true) because I thought my loop works only for once and that might be solution.

I'm not sure what you're asking about but I found the area informations with prop command then I used them in the loop. But now I deleted double checks as you mentioned below.

Lastly, I replace 'subplot' with 'figure' and now it's all good.

Thank you again. All the best,

Aysenur

Answer 1

[Jan]

rgb = insertText(I,[prop.Centroid(i,1) prop.Centroid(i,2)],'5kr', ...
    'FontSize',48,'TextColor','black');

This inserts the text into the original image I in each iteration and former changes are overwritten.

Better:

rgb = I;   % Create a copy to accumulate the insertes text objects
for i = 1:num
    if prop.Area(i) > 1.4e+06
        msg      = '1tl';
        totalAdd = 1.0;
    elseif prop.Area(i) > 1.2e+06  % No need to check Area(i) <= 1.4e6 again
        msg      = '50kr';
        totalAdd = 0.5;        
    ... and so on, please complete this by your own
    end
    
    % Avoid repeated code, but use variables: 
    rgb = insertText(rgb, [prop.Centroid(i,1), prop.Centroid(i,2)], msg, ...
        ... %        ^^^  not the original image I
        'FontSize',48,'TextColor','black');
    total = totalAdd;
end

If you want to change e.g. the fontsize, you have to modify one line only with this method.