如何在打开的CV中旋转边界框并对其进行裁剪（python）

Question

我有一个矩形的坐标（XMIN，YMIN，XMAX&；YMAX）在一个特定的图像上。我希望以特定角度旋转矩形，然后从图像中裁剪它。 我该怎么做

例如，这个image。我得到了显示在左侧的输出边界框（使用XMIN、YMIN、XMAX和YMAX绘制）。我想根据右边的图像旋转它，然后裁剪它

有人可以提供一个示例代码来获取这个输出，或者给我一个解释链接吗

Answer 1

在Python/OpenCV中有一种方法

• 读取输入
• 转乘高速列车
• 在绿色框上进行颜色阈值设置
• 获取外部轮廓
• 打印边界框
• 将图像旋转10度左右
• 将该图像转换为HSV
• 在旋转的绿色框上进行颜色阈值设置
• 获取外部轮廓
• 创建带有白色填充轮廓的黑色图像
• 获取白色像素坐标
• 从坐标中获取minareact
• 获取旋转矩形的顶点
• 在旋转的图像上绘制旋转的矩形轮廓

输入：

import cv2
import numpy as np
from scipy import ndimage

# load image
img = cv2.imread("berry.png")

# convert to hsv
hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)

# threshold using inRange or green
range1 = (20,200,170)
range2 = (80,255,255)
thresh = cv2.inRange(hsv,range1,range2)

# get bounding box coordinates from the one outer contour
contours = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
contours = contours[0] if len(contours) == 2 else contours[1]
x,y,w,h = cv2.boundingRect(contours[0])
print("bounding_box(x,y,w,h):",x,y,w,h)

# rotate image by 10 degree clockwise
rotated = img.copy()
rotated = ndimage.rotate(img, -10, cval=255)


# convert rotated to hsv
hsv_rotated = cv2.cvtColor(rotated, cv2.COLOR_BGR2HSV)

# threshold using inRange or green
range1 = (20,200,170)
range2 = (80,255,255)
thresh_rotated = cv2.inRange(hsv_rotated,range1,range2)

# get bounding box coordinates from the one outer contour
contours = cv2.findContours(thresh_rotated, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
contours = contours[0] if len(contours) == 2 else contours[1]

# draw white filled contour on black background
mask = np.zeros_like(thresh_rotated)
cv2.drawContours(mask, [contours[0]], -1, (255), -1)

# get coordinates of white pixels in mask
coords = np.column_stack(np.where(mask.transpose() > 0))

# get rotated rectangle
rotrect = cv2.minAreaRect(coords)

# rotated rectangle box points
box = np.int0(cv2.boxPoints(rotrect))
print("rotate_box_corners:\n",box)

# draw rotated rectangle on rotated image
result = rotated.copy()
cv2.polylines(result, [box], True, (0,0,255), 1)


# write result to disk
cv2.imwrite("berry_thresh.png", thresh)
cv2.imwrite("berry_rotated.png", rotated)
cv2.imwrite("berry_thresh_rotated.png", thresh_rotated)
cv2.imwrite("berry_mask.png", mask)
cv2.imwrite("berry_rotated_box.png", result)

# display results
cv2.imshow("THRESH", thresh)
cv2.imshow("ROTATED", rotated)
cv2.imshow("THRESH_ROT", thresh_rotated)
cv2.imshow("MASK", mask)
cv2.imshow("RESULT", result)
cv2.waitKey(0)
cv2.destroyAllWindows()

输入中绿线的阈值：

旋转输入：

旋转图像中绿线的阈值：

已填充阈值：

在旋转图像上显示旋转矩形的结果：

输入边界框：

bounding_box(x,y,w,h): 12 13 212 124

输出顶点：

rotate_box_corners:
 [[222 172]
 [ 14 136]
 [ 35  14]
 [243  51]]