Load image

English translation

Load image

rgb = imread('coloredChips.png'); % MATLAB built-in image

imshow(rgb)

Color sample image of red, green, blue, yellow and other circular chips on a light background, before a diameter measurement line is drawn.

Measure the diameter of a circle

d = drawline; % Drag the mouse in the figure

Circular-chip sample after drawing a diameter measurement line with drawline. A line with two endpoints crosses a yellow chip on the left.

pos = d.Position;

diffPos = diff(pos);

diameter = hypot(diffPos(1),diffPos(2))

diameter = 45.8496

Grayscale

gray_image = im2gray(rgb);
imshow(gray_image)

Find circle

[centers,radii] = imfindcircles(rgb,[20 25],'ObjectPolarity', 'dark')

Control sensitivity

[centers,radii] = imfindcircles(rgb,[20 25],'ObjectPolarity', 'dark', ...
 'sensitivity', 0.9)

Notify the found circles

imshow(rgb)
h = viscircles(centers,radii);

Increase sensitivity

[centers,radii] = imfindcircles(rgb,[20 25],'ObjectPolarity', 'dark', ...
 'sensitivity', 0.92);
length(centers)
delete(h)  % Delete previously drawn circles
h = viscircles(centers,radii);

Try another method

[centers,radii] = imfindcircles(rgb,[20 25],'ObjectPolarity', 'dark', ...
 'Sensitivity', 0.92, 'Method', 'twostage');
length(centers)
delete(h)
h = viscircles(centers,radii);

For the yellow ones

[centersBright,radiiBright] = imfindcircles(rgb,[20 25], 'ObjectPolarity','bright', ...
 'Sensitivity',0.92);
imshow(rgb)
hBright = viscircles(centersBright, radiiBright, 'Color', 'b');

Modify edge threshold

[centersBright,radiiBright] = imfindcircles(rgb,[20 25], 'ObjectPolarity', 'bright', ...
 'Sensitivity', 0.92, 'EdgeThreshold', 0.1);
imshow(rgb)
hBright = viscircles(centersBright, radiiBright, 'Color', 'b');

Add the previous ones

h = viscircles(centers,radii);

Merge the circle lists

centers = [centers; centersBright];
radii = [radii; radiiBright];
delete(h)
h = viscircles(centers,radii);