如何找到对象(形状)的方向?- Python Opencv

2022-01-16 00:00:00 python opencv image-processing rotation

问题描述

我的图像总是这样:

但我需要将它们旋转成这样:

But I need to rotate them to be like this:

但要做到这一点，我需要找到对象的方向，知道对象的较薄部分必须在左侧.总之，图像是翅膀，翅膀的起点必须在左侧，翅膀的末端必须在右侧.

But to do that, I need to find the orientation of the object, knowing that the thinner part of the object has to be on the left side. In summary, the images are wings and the start of the wing has to be on the left side and the end of the wing has to be on the right side.

我希望有人能给我一个建议，我尝试了很多不同的策略，但到目前为止都没有好的结果.

I hope someone can give me a suggestion, I've tried a bunch of different strategies but with no good result so far.

解决方案

这是 Python/OpenCV 中的一种方法.

Here is one way in Python/OpenCV.

  • 阅读图片

  • Read the image

转为灰度

阈值

获取外轮廓

从外轮廓获取 minAreaRect 点和角度

Get minAreaRect points and angle from outer contour

获取旋转矩形的顶点

画出旋转的矩形

根据需要校正角度

打印角度

保存带有旋转矩形的图像

Save the image with the rotated rectangle drawn on it

import cv2
import numpy as np

# load image as HSV and select saturation
img = cv2.imread("wing2.png")
hh, ww, cc = img.shape

# convert to gray
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

# threshold the grayscale image
ret, thresh = cv2.threshold(gray,0,255,0)

# find outer contour
cntrs = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cntrs = cntrs[0] if len(cntrs) == 2 else cntrs[1]

# get rotated rectangle from outer contour
rotrect = cv2.minAreaRect(cntrs[0])
box = cv2.boxPoints(rotrect)
box = np.int0(box)

# draw rotated rectangle on copy of img as result
result = img.copy()
cv2.drawContours(result,[box],0,(0,0,255),2)

# get angle from rotated rectangle
angle = rotrect[-1]

# from https://www.pyimagesearch.com/2017/02/20/text-skew-correction-opencv-python/
# the `cv2.minAreaRect` function returns values in the
# range [-90, 0); as the rectangle rotates clockwise the
# returned angle trends to 0 -- in this special case we
# need to add 90 degrees to the angle
if angle < -45:
    angle = -(90 + angle)
 
# otherwise, just take the inverse of the angle to make
# it positive
else:
    angle = -angle

print(angle,"deg")

# write result to disk
cv2.imwrite("wing2_rotrect.png", result)

cv2.imshow("THRESH", thresh)
cv2.imshow("RESULT", result)
cv2.waitKey(0)
cv2.destroyAllWindows()


返回角度:0.8814040422439575 度

带有旋转矩形的图像:


Angle Returned: 0.8814040422439575 deg

Image with Rotated Rectangle:

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