def find_circles(image):
    """
    takes and input image and find circles in it.

    returns radius and center coordinates of circles
    """
    import numpy as np
    import matplotlib.pyplot as plt
    from skimage import data, color
    from skimage.transform import hough_circle, hough_circle_peaks
    from skimage.feature import canny
    from skimage.draw import circle_perimeter
    from skimage.util import img_as_ubyte
    image = img_as_ubyte(image)
    edges = canny(image, sigma=2, low_threshold=10, high_threshold=20)
    hough_radii = np.arange(40, 280, 5)
    hough_res = hough_circle(edges, hough_radii)
    accums, cx, cy, radii = hough_circle_peaks(hough_res, hough_radii,
        total_num_peaks=7)
    fig, ax = plt.subplots(ncols=1, nrows=1, figsize=(10, 4))
    image = color.gray2rgb(image)
    for center_y, center_x, radius in zip(cy, cx, radii):
        circy, circx = circle_perimeter(center_y, center_x, radius, shape=
            image.shape)
        image[circy, circx] = 220, 20, 20
    ax.imshow(image, cmap=plt.cm.gray)
    plt.show()
