使用 opencv 去除眩光并保持边缘从眩光中去除

Question

I have this image: https://imgur.com/9A7542w

And i am trying to get the contours of the image but as we can see in this: https://imgur.com/VU7KqiS where there is glare, the contours of some circles are not drawn.

I assume that if i get the glare off on this photo, when i use canny, the edges will be drawn correctly?

I am new to openCV, i've read some post on here and tried out some techniques, but it didn't work out at all.

Note: i am doing this in python Anyone could help? Thanks a lot.

What i tried first:

import cv2 as cv

img = cv.imread('Photos/board.jpg')

canny = cv.Canny(img, 125, 175)

contours, hierarchies = cv.findContours(canny, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE)

blank = np.zeros(img.shape, dtype='uint8')
cv.drawContours(blank, contours, -1, (0,0,255),1)
cv.imshow('Contours drawn', blank)

results : https://imgur.com/yLVFCh2

Second attempt a bit better but useless things appears in the result

adaptive_thresh = cv.adaptiveThreshold(gray, 255, cv.ADAPTIVE_THRESH_MEAN_C, cv.THRESH_BINARY, 13, 2)
cv.imshow('Adaptive thresholding', adaptive_thresh)

canny = cv.Canny(adaptive_thresh, 125, 175)
cv.imshow('Canny edges', canny)

Results (Theres so much white pixels that appear on the photo: https://imgur.com/mqljl1m

Answer 1

I think the easiest way to do this is to change the 2nd value of your Canny detection like this:

canny = cv.Canny(img, 25, 175)

the lower threshold (second argument) is set lower then you can avoid this glare effect. More info here

From my point of view, you can also work in hsv space which is more confomfortable if you want to extract informations from images with effects like this. More info about hsv . The Fig. 3 a) speaks for itself.

Here is the full code, you had some errors in yours (and maybe you use an old opencv release)

import numpy as np
img = cv.imread(r'C:\Users\MyUser\Desktop\board.jpeg')
canny = cv.Canny(img, 25, 175)

img2, contours, hierarchy = cv.findContours(canny, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE)

blank = np.zeros(img.shape, dtype='uint8')
cv.drawContours(blank, contours, -1, (0,0,255),1)
cv.imshow('Contours drawn', blank)
cv.waitKey(0)

EDIT: I also want to tell you that it'll be difficult to use the extracted coordinates here. You'd better use circle detection and line detection to extract and use the coordinates of the board and pucks.