如何在使用霍夫圆（无轮廓）检测到的圆上绘制矩形？

Question

我想在圆上画一个矩形，这是我在人眼图片上使用霍夫圆函数得到的。要绘制一个矩形，我需要根据 cv2.rectange 的语法得到边 x 坐标、边 y 坐标、高度和宽度。但是霍夫圆给了我 center-x, center-y, radius 作为输出。有没有办法通过操纵霍夫圆输出来绘制矩形？我有点无能为力，我找不到任何关于类似请求的明确解释...注意：我没有使用轮廓，因为它 suitable/working 不适合我的输入

提前致谢！

代码如下：



import cv2
import numpy as np

#show image
def display_image(name,current_image):
    cv2.imshow(name,current_image)
    cv2.waitKey(0)

def image_processing(current_image):
    #Grayscaling
    grayscaled_image = cv2.cvtColor(current_image, cv2.COLOR_BGR2GRAY)
    #display_image("Gray",grayscaled_image)

    #Inverting
    inverted_image = cv2.bitwise_not(grayscaled_image)
    #display_image("Invert",inverted_image)

    #Removing Reflection
    kernel = np.ones((5, 5), np.uint8)
    blackhat_image = cv2.morphologyEx(inverted_image,cv2.MORPH_BLACKHAT,kernel)
    #display_image("Backhat",blackhat_image)

    removed_refection = cv2.addWeighted(src1=inverted_image,alpha=0.5,src2=blackhat_image,beta=0.5,gamma=0)
    #display_image("Removed reflection",removed_refection)

    image_without_reflection =  cv2.medianBlur(removed_refection, 5)
    #display_image("No reflection",image_without_reflection)

    #Thresholding
    _,thresholded_image= cv2.threshold(image_without_reflection,100,255,cv2.THRESH_BINARY)
    #display_image("Thresholded",thresholded_image)

    #Canny
    region_of_interest = cv2.bitwise_not(thresholded_image)
    canny_image = cv2.Canny(region_of_interest, 200, 100)

    return canny_image

def iris_detection(image):
    
    
    circles = cv2.HoughCircles(processed_image, cv2.HOUGH_GRADIENT, 1, 20, param1 = 200, param2 = 20, minRadius = 0)
    
    if circles is not None:
        
        #Mark circles co-ordinates
        inner_circle = np.uint16(np.around(circles[0][0])).tolist()
        cv2.circle(current_image, (inner_circle[0], inner_circle[1]), inner_circle[2], (0, 255, 0), 1)
        display_image("Final",current_image)
        
    radius = inner_circle[2]*0.2645833333
    diameter = radius * 2

    print("The Radius of the iris is:",radius,"mm")
    print("The Diameter of the iris is:",diameter,"mm")
    

#input
current_image = cv2.imread("eye.png", 1)
display_image("Original",current_image)

#Image pre-processing
processed_image = image_processing(current_image)
display_image("Processed Image",processed_image)

#Iris Detection using Hough circles
iris_detection(processed_image)

cv2.destroyAllWindows()```


  [Input][1][1]: https://i.stack.imgur.com/oKxC0.png
  [output][1][1]: https://i.stack.imgur.com/mjypO.png

Answer 1

只需对你的圆做数学运算，找到与照片平行的矩形（正方形）（你可以支持旋转的矩形，涉及更多数学）。

X_min_rect = X_circle - R

Y_min_rect = Y_circle - R

其中 R 是圆的半径。

宽度和高度等于 2*R

如何在使用霍夫圆（无轮廓）检测到的圆上绘制矩形？

How to draw a rectangle over a circle detected using Hough circle (without contours)?

python

opencv

computer-vision

hough-transform

iris-recognition