Extraction part of image that matches to a mask in OpenCV

Question

In a OpenCV application with Python , i have a mask and an RGB image, i want to extract part of image that matches to mask but i dont know how.

for example this is a mask:

and i want to do like this:

i do this:

temp = cv2.bitwise_and(img ,img, mask=feature_map)

but it gives me and error:

cv2.error: /Users/mee/opencv/modules/core/src/arithm.cpp:1589: error: (-215) (mtype == CV_8U || mtype == CV_8S) && _mask.sameSize(*psrc1) in function binary_op

Answer 1

You can do something like:

mask = cv2.imread('mask.png',0)
im = cv2.imread('guy.png')
mask_inv =  255 - mask;
final_im = mask_inv*im

Answer 2

您应该将掩码转换为对象掩码像素值为255且背景像素值为0.之后，您可以使用新掩码对RGB图像的每个颜色通道应用和操作或乘法运算。