OpenCV-Applications/ContoursEllipses.py at master · eeyribas/OpenCV-Applications · GitHub

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import numpy as np
import cv2
from matplotlib import pyplot as plt

def Roundness(contour, moments):
    length=cv2.arcLength(contour, True)
    k=(length*length)/(moments['m00']*4*np.pi)
    return k

def GetPositionToDraw(text, point, fontFace, fontScale, thickness):
    textSize=cv2.getTextSize(text, fontFace, fontScale, thickness)[0]
    textX=point[0]-textSize[0]/2
    textY=point[1]+textSize[1]/2
    return round(textX), round(textY)

def EccentricityFromEllipse(contour):
    (x, y), (MA, ma), angle=cv2.fitEllipse(contour)
    a=ma/2
    b=MA/2
    ecc=np.sqrt(a**2-b**2)/a
    return ecc

def EccentricityFromMoments(moments):
    a1=(moments['mu20']+moments['mu02'])/2
    a2=np.sqrt(4*moments['mu11']**2+(moments['mu20']-moments['mu02'])**2)/2
    ecc=np.sqrt(1-(a1-a2)/(a1+a2))
    return ecc

def BuildImageEllipses():
    img=np.zeros((500, 600, 3), dtype="uint8")
    cv2.ellipse(img, (120, 60), (100, 50), 0, 0, 360, (255, 255, 0), -1)
    cv2.ellipse(img, (300, 60), (50, 50), 0, 0, 360, (0, 0, 255), -1)
    cv2.ellipse(img, (425, 200), (50, 150), 0, 0, 360, (255, 0, 0), -1)
    cv2.ellipse(img, (550, 250), (20, 240), 0, 0, 360, (255, 0, 255), -1)
    cv2.ellipse(img, (200, 200), (150, 50), 0, 0, 360, (0, 255, 0), -1)
    cv2.ellipse(img, (250, 400), (200, 50), 0, 0, 360, (0, 255, 255), -1)
    return img

def DrawContourOutline(img, cnts, color, thickness=1):
    for cnt in cnts:
        cv2.drawContours(img, [cnt], 0, color, thickness)

def ShowImgWithMatplotlib(colorImg, title, pos):
    imgRGB=colorImg[:, :, ::-1]
    ax=plt.subplot(1, 2, pos)
    plt.imshow(imgRGB)
    plt.title(title)
    plt.axis('off')

fig=plt.figure(figsize=(14, 6))
plt.suptitle("Eccentricity", fontsize=14, fontweight='bold')
fig.patch.set_facecolor('silver')

image=BuildImageEllipses()
grayImage=cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
ret, thresh=cv2.threshold(grayImage, 20, 255, cv2.THRESH_BINARY)
contours, hierarchy=cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
print("detected contours: '{}' ".format(len(contours)))

imgNumbers=image.copy()
for contour in contours:
    DrawContourOutline(image, [contour], (255, 255, 255), 5)
    M=cv2.moments(contour)
    k=Roundness(contour, M)
    print("roundness: '{}'".format(k))

    em=EccentricityFromMoments(M)
    print("eccentricity: '{}'".format(em))
    ee=EccentricityFromEllipse(contour)
    print("eccentricity: '{}'".format(ee))

    cX=int(M['m10']/M['m00'])
    cY=int(M['m01']/M['m00'])
    textToDraw=str(round(em, 3))
    (x, y)=GetPositionToDraw(textToDraw, (cX, cY), cv2.FONT_HERSHEY_SIMPLEX, 1, 3)
    cv2.putText(imgNumbers, textToDraw, (x, y), cv2.FONT_HERSHEY_SIMPLEX, 1, (255, 255, 255), 3)

ShowImgWithMatplotlib(image, "image", 1)
ShowImgWithMatplotlib(imgNumbers, "ellipses eccentricity", 2)
plt.show()