[英]Python OpenCV: draw outer contours inside a specific contour
I'm new to OpenCV and I'm trying to draw the outer contours inside a specific contour.我是 OpenCV 的新手,我正在尝试在特定轮廓内绘制外部轮廓。 Here's the image I'm using to clarify (already grayscaled, thresholded, etc.)
这是我用来澄清的图像(已经灰度化、阈值化等)
What I want is to find all the contours of the circles (120 in total), inside the outer rectangle.我想要的是在外部矩形内找到圆圈的所有轮廓(总共 120 个)。
contours = cv2.findContours(image, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
So I basically used RETR_EXTERNAL
for this but it only returns the outer rectangle.所以我基本上为此使用了
RETR_EXTERNAL
但它只返回外部矩形。 I tried using RETR_TREE
but in that case it's returning me way more contours than there are circles, for some reason I don't understand.我尝试使用
RETR_TREE
但在那种情况下,它返回的轮廓比圆圈多,出于某种原因我不明白。 To clarify: I just want 1 contour per circle.澄清一下:我只想要每个圆圈 1 个轮廓。
How can I use RETR_EXTERNAL
and ignore the outer contour (rectangle), so that it only returns the circles?如何使用
RETR_EXTERNAL
并忽略外轮廓(矩形),以便它只返回圆?
I filtered the contours by area to isolate the circles.我按区域过滤轮廓以隔离圆圈。 I think you may need to work on thresholding the image a bit more to help delineate the circles from the border in the image.
我认为您可能需要对图像进行更多的阈值处理,以帮助从图像中的边界描绘圆圈。 I used the following code:
我使用了以下代码:
import cv2
import numpy as np
img = cv2.imread("/your/path/C03eN.jpg")
def find_contours_and_centers(img_input):
img_gray = cv2.cvtColor(img_input, cv2.COLOR_BGR2GRAY)
img_gray = cv2.bilateralFilter(img_gray, 3, 27,27)
#(T, thresh) = cv2.threshold(img_input, 0, 100, 0)
_, contours_raw, hierarchy = cv2.findContours(img_gray, cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
contours = [i for i in contours_raw if cv2.contourArea(i) > 20]
contour_centers = []
for idx, c in enumerate(contours):
M = cv2.moments(c)
cX = int(M["m10"] / M["m00"])
cY = int(M["m01"] / M["m00"])
samp_bounds = cv2.boundingRect(c)
contour_centers.append(((cX,cY), samp_bounds))
print("{0} contour centers and bounds found".format(len(contour_centers)))
contour_centers = sorted(contour_centers, key=lambda x: x[0])
return (contours, contour_centers)
conts, cents = find_contours_and_centers(img.copy())
circles = [i for i in conts if np.logical_and((cv2.contourArea(i) > 650),(cv2.contourArea(i) < 4000))]
cv2.drawContours(img, circles, -1, (0,255,0), 2)
cv2.imwrite("/your/path/tester.jpg", img)
If you just want to extract the portion of the image that is inside the larger outer rectangle, using cv2.RETR_EXTERNAL
, allowing you to focus on the inner circles you can do something like the following:如果您只想提取较大外部矩形内的图像部分,请使用
cv2.RETR_EXTERNAL
,让您专注于内部圆圈,您可以执行以下操作:
import cv2
import numpy as np
img = cv2.imread("/your/path/C03eN.jpg")
def find_contours_and_centers(img_input):
img_gray = cv2.cvtColor(img_input, cv2.COLOR_BGR2GRAY)
img_gray = cv2.bilateralFilter(img_gray, 3, 27,27)
#(T, thresh) = cv2.threshold(img_input, 0, 100, 0)
#_, contours_raw, hierarchy = cv2.findContours(img_gray, cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
_, contours_raw, hierarchy = cv2.findContours(img_gray, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
contours = [i for i in contours_raw if cv2.contourArea(i) > 20]
contour_centers = []
for idx, c in enumerate(contours):
M = cv2.moments(c)
cX = int(M["m10"] / M["m00"])
cY = int(M["m01"] / M["m00"])
samp_bounds = cv2.boundingRect(c)
contour_centers.append(((cX,cY), samp_bounds))
print("{0} contour centers and bounds found".format(len(contour_centers)))
contour_centers = sorted(contour_centers, key=lambda x: x[0])
return (contours, contour_centers)
conts, cents = find_contours_and_centers(img.copy())
x,y,w,h = cv2.boundingRect(conts[0])
cropped = img[y+10:y+(h-10),x+10:x+(w-10)]
cv2.imwrite("/your/path/cropped.jpg", cropped)
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