circle_perimeter_aa(r, c, radius, shape=None)

Notes

Wu's method draws anti-aliased circle. This implementation doesn't use lookup table optimization.

Use the function draw.set_color to apply circle_perimeter_aa results to color images.

Parameters

r, c : int

Centre coordinate of circle.

radius : int

Radius of circle.

shape : tuple, optional

Image shape which is used to determine the maximum extent of output pixel coordinates. This is useful for circles that exceed the image size. If None, the full extent of the circle is used. Must be at least length 2. Only the first two values are used to determine the extent of the input image.

Returns

rr, cc, val : (N,) ndarray (int, int, float)

Indices of pixels (:None:None:`rr`, :None:None:`cc`) and intensity values (:None:None:`val`). img[rr, cc] = val .

Generate anti-aliased circle perimeter coordinates.

Examples

This example is valid syntax, but we were not able to check execution

>>> from skimage.draw import circle_perimeter_aa
... img = np.zeros((10, 10), dtype=np.uint8)
... rr, cc, val = circle_perimeter_aa(4, 4, 3)
... img[rr, cc] = val * 255
... img
array([[  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
       [  0,   0,  60, 211, 255, 211,  60,   0,   0,   0],
       [  0,  60, 194,  43,   0,  43, 194,  60,   0,   0],
       [  0, 211,  43,   0,   0,   0,  43, 211,   0,   0],
       [  0, 255,   0,   0,   0,   0,   0, 255,   0,   0],
       [  0, 211,  43,   0,   0,   0,  43, 211,   0,   0],
       [  0,  60, 194,  43,   0,  43, 194,  60,   0,   0],
       [  0,   0,  60, 211, 255, 211,  60,   0,   0,   0],
       [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
       [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0]], dtype=uint8)

This example is valid syntax, but we were not able to check execution

>>> from skimage import data, draw
... image = data.chelsea()
... rr, cc, val = draw.circle_perimeter_aa(r=100, c=100, radius=75)
... draw.set_color(image, (rr, cc), [1, 0, 0], alpha=val)

See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

skimage.segmentation.active_contour_model.active_contour skimage.draw.draw.circle_perimeter_aa skimage.transform.hough_transform.hough_circle skimage.transform.hough_transform.hough_circle_peaks

Local connectivity graph

Hover to see nodes names; edges to Self not shown, Caped at 50 nodes.

Using a canvas is more power efficient and can get hundred of nodes ; but does not allow hyperlinks; , arrows or text (beyond on hover)

SVG is more flexible but power hungry; and does not scale well to 50 + nodes.

All aboves nodes referred to, (or are referred from) current nodes; Edges from Self to other have been omitted (or all nodes would be connected to the central node "self" which is not useful). Nodes are colored by the library they belong to, and scaled with the number of references pointing them

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