## Detects multiple disks (coins) in an image using Hough Transform

Version 1.5.0.0 (3.17 KB) by
HOUGHCIRCLES detects multiple disks (coins) in an image using Hough Transform.

Updated Wed, 07 Jan 2009 23:25:29 +0000

HOUGHCIRCLES detects multiple disks (coins) in an image using Hough Transform. The image contains separating, touching, or overlapping disks whose centers may be in or out of the image.

Syntax
houghcircles(im, minR, maxR);
houghcircles(im, minR, maxR, thresh);
houghcircles(im, minR, maxR, thresh, delta);
circles = houghcircles(im, minR, maxR);
circles = houghcircles(im, minR, maxR, thresh);
circles = houghcircles(im, minR, maxR, thresh, delta);

Inputs:
- im: input image
- minR: minimal radius in pixels
- maxR: maximal radius in pixels
- thresh (optional): the minimal ratio of the number of detected edge pixels to 0.9 times the calculated circle perimeter (0<thresh<=1, default: 0.33)
- delta (optional): the maximal difference between two circles for them to be considered as the same one (default: 12); e.g., c1=(x1 y1 r1), c2=(x2 y2 r2), delta = |x1-x2|+|y1-y2|+|r1-r2|

Output
- circles: n-by-4 array of n circles; each circle is represented by (x y r t), where (x y), r, and t are the center coordinate, radius, and ratio of the detected portion to the circle perimeter, respectively. If the output argument is not specified, the original image will be displayed with the detected circles superimposed on it.

### Cite As

Randy Tang (2023). Detects multiple disks (coins) in an image using Hough Transform (https://www.mathworks.com/matlabcentral/fileexchange/22543-detects-multiple-disks-coins-in-an-image-using-hough-transform), MATLAB Central File Exchange. Retrieved .

##### MATLAB Release Compatibility
Created with R2007b
Compatible with any release
##### Platform Compatibility
Windows macOS Linux
##### Acknowledgements

Inspired: TACTICS Toolbox

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Version Published Release Notes
1.5.0.0

Minor modifications according to Sven's suggestions. Thanks a lot, Sven.

1.3.0.0

Major modifications of the program.

1.2.0.0

Description of the format of function invocation is corrected.

1.1.0.0

Description about the format of function invocation is corrected.

1.0.0.0