如何使用OpenCV处理的图像将小图像粘贴到python中心的另一个大图像上？

Question

我正在学习OpenCV，并尝试在大图像上粘贴小图像。 但是，由于两个图像的大小均应相等，因此显示错误。 我还尝试遵循提供的建议（ 如何使用Pillow将图像粘贴到更大的图像上？ ）和（ 如何使用Python中的PIL将图像合成到另一个图像上？ ）

   import cv2 as cv
   from scipy import ndimage

   img1 = cv.imread('Please put your file name')

   top_left_x = min([x1,x2,x3,x4])
   top_left_y = min([y1,y2,y3,y4])
   bot_right_x = max([x1,x2,x3,x4])
   bot_right_y = max([y1,y2,y3,y4])

   y_right =bot_right_y + 1
   x_right =bot_right_x + 1

  cropped = img[top_left_y: y_right, top_left_x: x_right]

  rotate = ndimage.rotate(cropped, ang)

最终输出图像应居中。

Answer 1

这是一个纯PIL解决方案：-

from PIL import Image

img1 = Image.open(r"Source_Image_path")

# The values used to crop the original image (will form a bbox)
x1, y1, x2, y2 = 10, 10, 400, 400

# The angle at which the cropped Image must be rotated
angle = 50

# cropping the original image 
img = img1.crop((x1, y1, x2, y2))

# Firstly converting the Image mode to RGBA, and then rotating it
img = img.convert("RGBA").rotate(angle, resample=Image.BICUBIC)

# calibrating the bbox for the beginning and end position of the cropped image in the original image 
# i.e the cropped image should lie in the center of the original image
x1 = int(.5 * img1.size[0]) - int(.5 * img.size[0])
y1 = int(.5 * img1.size[1]) - int(.5 * img.size[1])
x2 = int(.5 * img1.size[0]) + int(.5 * img.size[0])
y2 = int(.5 * img1.size[1]) + int(.5 * img.size[1])

# pasting the cropped image over the original image, guided by the transparency mask of cropped image
img1.paste(img, box=(x1, y1, x2, y2), mask=img)

# converting the final image into its original color mode, and then saving it
img1.convert(img1.mode).save("Destination_path")

输入图像：

输出图像：

该代码本身是不言自明的，但是您可能想知道为什么我们将裁剪后的图像来回转换为RGBA 。 这样做的原因是，因为如果我们在PIL中旋转非alpha图像，则最终在图像上的黑条/边缘将出现像素值不再存在的情况（ 有关更多信息，请阅读此问题 ）。 但是，如果我们对Alpha图像执行相同操作，即通过rotate()传递Alpha图像，则空像素值最终将完全透明（或Alpha = 0）。

Answer 2

虽然，没有可用的解决方案可用于OpenCV，甚至无法解决我的问题。 但是，经过几次修改，我就能在OpenCV中解决此问题。

import cv2
img = cv2.imread('Please put your file name')

# Setting the parameters
ang = 47
top_left_x = min([12,42,53,11])
top_left_y = min([41,56,75,20])
bot_right_x = max([12,42,53,11])
bot_right_y = max([41,56,75,20])

y_right =bot_right_y + 1
x_right =bot_right_x + 1

# Cropping the image
cropped_img = img[top_left_y: y_right, top_left_x: x_right]

###########  Rotating the image ##########
# First setting the centre and roatation angle parameter. 
# To rotate sub-image from the centre of the original image
rows,cols = img.shape
M = cv2.getRotationMatrix2D((cols/2,rows/2),ang,1)

# Setting the size with original image to resolve size issue
rotated_img = cv2.warpAffine(cropped_img,M,(img.shape[1],img.shape[0]))

# Pasting the rotated image on original image
# The original image will be in the background with transparency 0.3
# The sub-image will be pasted above the original image with transparency 0.7
img = cv2.addWeighted(img, 0.3, rotated_img, 0.7, 0)

# Showing the image
cv2.namedWindow('img', cv2.WINDOW_NORMAL)
cv2.imshow('output_image.jpg', img)
cv2.waitKey(0)
cv2.destroyAllWindows()

这不是最合适的答案，但可以为我们许多人服务。