我如何使用opencv python仅更改白色的黑色而无像素操作

Question

This is the sample Image

I want to change the black color in the image into white. I tried using threshold and bitwise operations but these operations distorts the other color present in the image. I don't want to use pixel operations as these are expensive.

Answer 1

Apply a threshold operation on your source image using cv2.THRESH_INV argument, to ensure that only the black pixels change to white and the other pixels turn black.

Convert the binary mask to a 3 channel image by using:

src1_mask=cv2.cvtColor(src1_mask,cv2.COLOR_GRAY2BGR)#change mask to a 3 channel image

use cv2.addWeighted method to add the mask and the original image. The black part of the mask will be replaced by the original image and the white part will remain white, since the black pixels will be approximately 0 in the addWeighted operation

Answer 2

Load your source image as an array named 'img' and then do this:

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
mask = cv2.compare(gray,5,cv2.CMP_LT)
img[mask > 0] = 255