Once centroid is calculated, how to assign x & y coordinates to it to then put into further calculations

So as an overview, I have a picture with me holding two tags, one red one yellow.

I have then calulcated centroid to annotate the image with and caluclate the distance (City Block/Chessboard/Euclidean), as shown here:

The only problem I am facing is that to get the centroid coordinates of each tag, I am using the following code:

redCentroid = regionprops(redMorph, 'centroid');

While this does work, it forces me to obtain the centroid coordinates through the command window. then assign them manually to x,y or i,j to the put into my distance calculations.

I am just wondering if there is a way to automatically designate the centroid coordinates to x & y (or i & j), instead of manually calculating through current method in command window then assigning to variable.

My full code is below:

clear all;

close all;

clc;

RGB = imread('tagPhoto.bmp');

%Yellow Tag

yellowChannel1Min = 0.000;

yellowChannel1Max = 255.000;

yellowChannel2Min = 71.000;

yellowChannel2Max = 255.000;

yellowChannel3Min = 0.000;

yellowChannel3Max = 40.000;

yellowSliderBW = (RGB(:,:,1) >= yellowChannel1Min ) & (RGB(:,:,1) <= yellowChannel1Max) & ...

(RGB(:,:,2) >= yellowChannel2Min ) & (RGB(:,:,2) <= yellowChannel2Max) & ...

(RGB(:,:,3) >= yellowChannel3Min ) & (RGB(:,:,3) <= yellowChannel3Max);

yellowBW = yellowSliderBW;

%Red Tag

redChannel1Min = 71.000;

redChannel1Max = 255.000;

redChannel2Min = 0.000;

redChannel2Max = 41.000;

redChannel3Min = 0.000;

redChannel3Max = 54.000;

redSliderBW = (RGB(:,:,1) >= redChannel1Min ) & (RGB(:,:,1) <= redChannel1Max) & ...

(RGB(:,:,2) >= redChannel2Min ) & (RGB(:,:,2) <= redChannel2Max) & ...

(RGB(:,:,3) >= redChannel3Min ) & (RGB(:,:,3) <= redChannel3Max);

redBW = redSliderBW;

%Calculate Red Tag Centroid Coordinates

redSE = strel("rectangle",[5 4]);

redOpen = imopen(redBW, redSE);

redMorph = imclose(redOpen, ones(25));

redCentroid = regionprops(redMorph, 'centroid');

%Calculate Yellow Tag Centroid Coordinates

yellowMorph = imclose(yellowBW, ones(25));

yellowCentroid = regionprops(yellowMorph, 'centroid');

%Yellow/Red centroid coordinates

ri = 255.9213;

rj = 89.2483;

yi = 258.3529;

yj = 498.7177;

dCityBlock = (abs(ri - yi)) + (abs(rj - yj));

dChessboard = max(abs(ri - yi), abs(rj - yj));

dEuclidean = sqrt((ri - yi)^2 + (rj - yj)^2);

disp(['City Block Distance: ' num2str(dCityBlock)]);

disp(['Chessboard Distance: ' num2str(dChessboard)]);

disp(['Euclidean Distance: ' num2str(dEuclidean)]);

figure;

imshow(RGB);

hold on;

plot(89.2483,255.9213, 'g-x', 'LineWidth',5)

plot(498.7177,258.3529, 'g-x', 'LineWidth',5)

plot([89.2483,498.7177],[255.9213,258.3529],'b','LineWidth',2);

Thanks in advance for any help!

Answer 1

[DGM]

You should just be able to get them from the struct.

%Yellow/Red centroid coordinates
ri = redCentroid.Centroid(2);
rj = redCentroid.Centroid(1);
yi = yellowCentroid.Centroid(2);
yj = yellowCentroid.Centroid(1);

[Ted]

Hi, great this worked for what I needed. Thanks.