python - 将 1 channel 骨架图像叠加到 3 channel RGB 图像上

Question

我有兴趣将骨架像素为 255(白色)的黑白骨架图像叠加到 3 channel RGB 图像上。我并不偏向于使用 OpenCV，但是当我使用 add 函数时，我得到了形状不兼容的错误。

这样做的方法是什么？

import cv2
skl_img = cv2.imread("sample_skeleton_image/579366_2_train2017_skel.png", 0) 
print(skl_img.shape)
plt.imshow(skl_img)

224x400

obj_img = cv2.imread("/content/drive/Shareddrives/Wish 2021/Code/sample_skeleton_image/579366_2_train2017.jpg", cv2.IMREAD_COLOR)
plt.imshow(obj_img)

obj_img shape is 224x400x3

final_img = cv2.add(obj_img,skl_img)
plt.imshow(final_img)

---

error                                     Traceback (most recent call last)
<ipython-input-27-7de7a4136982> in <module>()
----> 1 final_img = cv2.add(obj_img,skl_img)
      2 plt.imshow(final_img)

error: OpenCV(4.1.2) /io/opencv/modules/core/src/arithm.cpp:663: error: (-209:Sizes of input arguments do not match) The operation is neither 'array op array' (where arrays have the same size and the same number of channels), nor 'array op scalar', nor 'scalar op array' in function 'arithm_op'

基本上，我对最终图像感兴趣，如下所示:

Answer 1

以下是在 Python 中将 mask 应用到图像的其他几种方法。

输入:

面具:

import cv2
import numpy as np

# read image
img = cv2.imread('elephant_trunk.png')

# read mask as grayscale
mask = cv2.imread('elephant_trunk_skeleton.png', cv2.IMREAD_GRAYSCALE)

# Method 1: Numpy masking
result1 = img.copy()
result1[mask!=0] = (255,255,255)

# Method 2: Merge mask to 3 channels
mask2 = cv2.merge([mask,mask,mask])
result2 = cv2.add(img, mask2)

# Method 3: Convert mask to BGR
mask3 = cv2.cvtColor(mask, cv2.COLOR_GRAY2BGR)
result3 = cv2.add(img, mask3)

# save result
cv2.imwrite("elephant_trunk_masked.png", result1)

# show result
cv2.imshow("RESULT1", result1)
cv2.imshow("RESULT2", result2)
cv2.imshow("RESULT3", result3)
cv2.waitKey(0)

结果: