Showing the error "Variable nDimes has an incorrect value"

For this problem your code will need to do the following:

• Accurately determine the number of each coin type present. Use variable names nDimes, nNickels, nQuarters, and nFiftyCents.
• Calculate the total $ value of coins present. Use variable name USD

The code:

testImageIdx = randi([1,3]);
testCoinImage = imread("testCoinImage" + testImageIdx + ".png");

imshow(testCoinImage);
title("Original Coin Image");
[testcoinMask, MaskedtestCoin] = segmentCoin(testCoinImage);

se = strel('disk', 20, 0);
testCoinMask = imfill(testcoinMask, 'holes');
testCoinMask = imerode(testcoinMask, se);

imgFilt = imgaussfilt(MaskedtestCoin, 0.5, 'Padding', "circular", 'FilterDomain', "frequency", 'FilterSize', 3);
faceEdgeMask = edge(imgFilt, "sobel", 0.05, "both");

faceEdgeMask(~testcoinMask) = false;
imshow(faceEdgeMask);
title("Edge Mask Detection for Valid Coins");

see = strel("disk", 25, 0);
fb = imfill(faceEdgeMask, "holes");
Bw2 = imdilate(fb, see);

validCoinMask = Bw2 & testcoinMask;
set = strel("disk", 2, 0);
validCoinMask = imdilate(validCoinMask, set);
montage({testcoinMask, validCoinMask});
title("testcoinMask vs ValidCoinMask");

coinSizes = regionprops("table", validCoinMask, "Area");
nDimes = coinSizes.Area < 1100;
nDimes = sum(nDimes);
nNickels = (coinSizes.Area > 1100 & coinSizes.Area < 2200);
nNickels = sum(nNickels);
nQuarters = (coinSizes.Area > 2200 & coinSizes.Area < 3200);
nQuarters = sum(nQuarters);
nFiftyCents = coinSizes.Area >= 3200;
nFiftyCents = sum(nFiftyCents);
USD = (nDimes * 0.10) + (nNickels * 0.05) + (nQuarters * 0.25) + (nFiftyCents * 0.50);

function [testcoinMask, MaskedtestCoin] = segmentCoin(X)
X = im2gray(X);

testcoinMask = im2gray(X) > 150;
radius = 12;
decomp = 4;
se = strel('disk', radius, decomp);
testcoinMask = imclose(testcoinMask, se);
MaskedtestCoin = X;
MaskedtestCoin(~testcoinMask) = 0;
end

[Cris LaPierre]

Looks like you are working on the Final Analysis assignment in the Image Segmentation, Filtering, and Region Analysis course on Coursera.

When I use your code in some of the problems that preceed it, it returns errors as well. Have you been able to successfully pass the earlier problems?

• Segment the Foreground
• Valid Coin Face Edges
• Valid Coin Segmentation

[Shah]

In the earlier problems, there were no issues and the code met all the required assessment criterias.

[martin]

can you send me tha answer

Answer 1

[Cris LaPierre]

Inspect the criteria you are using to determine nDimes. Your code finds 11 dimes in each image, which is incorrect.

[Shah]

I have rechecked the detected areas and have adjusted the threshold of dimes, nickels, cents and quarters multiple times but the issue still persists.

@Cris LaPierre, could you please help me in modifying the code? Thank you in advance!

[Cris LaPierre]

I believe the issue you are having is that your mask is not the area of the coins. This makes it difficult when using area to distinguish between coin types. Here is the validCoinMask your code is creating:

I had to change the range of areas your code uses to identify the coins, and it still was getting some wrong because of this.

You want your mask to look like this (both are masks for test image 1).

Answer 2

[martin]

testImageIdx = randi([1,3])
testCoinImage = imread("testCoinImage"+testImageIdx+".png");
imshow(testCoinImage);
title("Original Coin Image");

[testcoinMask, MaskedtestCoin] = segmentCoin(testCoinImage);

% Shrink the coin mask to focus on the coin regions
se = strel('disk', 20, 0);
testcoinMask = imfill(testcoinMask, 'holes');
testcoinMask = imerode(testcoinMask, se);

% Apply Gaussian filter to the masked coin image
imgFilt = imgaussfilt(MaskedtestCoin, 0.5, 'Padding', 'circular', 'FilterDomain', 'frequency', 'FilterSize', 3);
faceEdgeMask = edge(imgFilt, 'sobel', 0.05, 'both');

% Eliminate edges outside the shrunken coin mask
faceEdgeMask(~testcoinMask) = false;
imshow(faceEdgeMask);
title("Edge Mask Detection for Valid Coins");

% Refine the edge mask and create valid coin mask
se_dilate = strel('disk', 25, 0);
fb = imfill(faceEdgeMask, 'holes');
Bw2 = imdilate(fb, se_dilate);

validCoinMask = Bw2 & testcoinMask;
se_final = strel('disk', 2, 0);
validCoinMask = imdilate(validCoinMask, se_final);

% Display comparison
montage({testcoinMask, validCoinMask});
title("testcoinMask vs ValidCoinMask");

% Count the number of each type of coin
coinSizes = regionprops('table', validCoinMask, 'Area');
nDimes = nnz(coinSizes.Area < 1100);
nNickels = nnz(coinSizes.Area >= 1100 & coinSizes.Area < 2200);
nQuarters = nnz(coinSizes.Area >= 2200 & coinSizes.Area < 3200);
nFiftyCents = nnz(coinSizes.Area >= 3200);

% Calculate the total USD value
USD = (nDimes * 0.10) + (nNickels * 0.05) + (nQuarters * 0.25) + (nFiftyCents * 0.50);

% Display the total value
disp(['Total USD Value: $', num2str(USD)]);

function [testcoinMask, MaskedtestCoin] = segmentCoin(X)
X = im2gray(X);

% Adjust the threshold value as needed
testcoinMask = X > 150;

% Refine mask with morphological operations
radius = 20; % Adjust this value if necessary
se = strel('disk', radius);
testcoinMask = imclose(testcoinMask, se);
testcoinMask = imfill(testcoinMask, 'holes');

MaskedtestCoin = X;
MaskedtestCoin(~testcoinMask) = 0;
end

Answer 3

[krishnaveni]

testImageIdx = randi([1,3])
testCoinImage = imread("testCoinImage"+testImageIdx+".png");


% Display the original image
imshow(testCoinImage);
title("Original Coin Image");

% Segment the coin from the image
[testcoinMask, MaskedtestCoin] = segmentCoin(testCoinImage);

% Perform morphological operations on the mask
se = strel('disk', 20, 0);
testCoinMask = imfill(testcoinMask, 'holes');
testCoinMask = imerode(testCoinMask, se);

% Apply Gaussian filtering and edge detection
imgFilt = imgaussfilt(MaskedtestCoin, 0.5, 'Padding', "circular", 'FilterDomain', "frequency", 'FilterSize', 3);
faceEdgeMask = edge(imgFilt, "sobel", 0.05, "both");

% Apply the edge mask to the coin mask
faceEdgeMask(~testCoinMask) = false;
imshow(faceEdgeMask);
title("Edge Mask Detection for Valid Coins");

% Refine the edge mask
see = strel("disk", 25, 0);
fb = imfill(faceEdgeMask, "holes");
Bw2 = imdilate(fb, see);

% Create a valid coin mask
validCoinMask = Bw2 & testCoinMask;
set = strel("disk", 2, 0);
validCoinMask = imdilate(validCoinMask, set);

% Display the masks
montage({testCoinMask, validCoinMask});
title("testcoinMask vs ValidCoinMask");

% Calculate coin sizes and classify them
coinSizes = regionprops(validCoinMask, 'Area');

% Initialize counters
nDimes = 0;
nNickels = 0;
nQuarters = 0;
nFiftyCents = 0;

% Define area thresholds for different coins
areaThresholds = struct('Dime', [0, 1100], 'Nickel', [1100, 2200], 'Quarter', [2200, 3200], 'FiftyCent', [3200, Inf]);

% Classify coins based on area
for k = 1:length(coinSizes)
    area = coinSizes(k).Area;
    if area > areaThresholds.Dime(1) && area <= areaThresholds.Dime(2)
        nDimes = nDimes + 1;
    elseif area > areaThresholds.Nickel(1) && area <= areaThresholds.Nickel(2)
        nNickels = nNickels + 1;
    elseif area > areaThresholds.Quarter(1) && area <= areaThresholds.Quarter(2)
        nQuarters = nQuarters + 1;
    elseif area > areaThresholds.FiftyCent(1)
        nFiftyCents = nFiftyCents + 1;
    end
end

% Calculate total USD
USD = (nDimes * 0.10) + (nNickels * 0.05) + (nQuarters * 0.25) + (nFiftyCents * 0.50);

% Display results
disp(['Number of Dimes: ', num2str(nDimes)]);
disp(['Number of Nickels: ', num2str(nNickels)]);
disp(['Number of Quarters: ', num2str(nQuarters)]);
disp(['Number of Fifty Cents: ', num2str(nFiftyCents)]);
disp(['Total USD: $', num2str(USD)]);

% Function for segmenting coins
function [testcoinMask, MaskedtestCoin] = segmentCoin(X)
    % Convert to grayscale
    X = im2gray(X);

    % Create a binary mask based on intensity
    testcoinMask = X > 150;
    radius = 12;
    decomp = 4;
    se = strel('disk', radius, decomp);
    testcoinMask = imclose(testcoinMask, se);

    % Mask the coin from the image
    MaskedtestCoin = X;
    MaskedtestCoin(~testcoinMask) = 0;
end