如何使用 python、opencv 从粘贴在相机输入上的图像中删除背景

Question

In python Opencv, I wanted to paste a drum image over my camera input and I have succeeded in the work but, there is a problem, The drum image has a transparent background and when I paste it a black coloured background appears, I want the background black colour to not appear in the output. I have seen many places but did not succeed and this is my last hope. Please help

# Importing modules
import cv2
import numpy
import time
# Video_capture using cv2
image = cv2.VideoCapture(0)
while True:
    # reading images
    success, img = image.read()
    drums_img = cv2.imread('media/drums_IMG.png')
    # resize image
    img1 = cv2.resize(img,(500,500))
    drums_img1 = cv2.resize(drums_img,(300,300))
    x_offset = y_offset = 100

    img1[y_offset:y_offset + drums_img1.shape[0], x_offset:x_offset + drums_img1.shape[1]] = drums_img1
    # Next

    # showing image
    cv2.imshow("Virtual Drums",img1)
    cv2.waitKey(1)

Answer 1

import cv2
import numpy as np

transparent = cv2.imread('transparent.png', cv2.IMREAD_UNCHANGED).astype(np.float32)/255
background = cv2.imread('background.jpg', cv2.IMREAD_UNCHANGED).astype(np.float32)/255

def put_transparent_to_image(image, transparent, x, y):
    h_t, w_t, *_ = transparent.shape
    transparent_alpha = np.zeros(background.shape[:2])
    transparent_alpha[y:y+h_t, x:x+w_t] = transparent[:,:,3]
    transparent_canvas = np.zeros_like(background)
    transparent_canvas[y:y+h_t, x:x+w_t] = transparent[:,:,:3]
    image[:,:,0] *= (1-transparent_alpha)
    image[:,:,1] *= (1-transparent_alpha)
    image[:,:,2] *= (1-transparent_alpha)
    transparent_canvas[:,:,0] * transparent_alpha
    transparent_canvas[:,:,1] * transparent_alpha
    transparent_canvas[:,:,2] * transparent_alpha
    result = image + transparent_canvas
    return result

result = put_transparent_to_image(background, transparent, 200, 400)
cv2.imwrite("result.jpg", (result*255).astype(np.uint8))

The mixing is not perfect, but you can start there. Basic idea is that we know alpha channel of our transparent image, so we can

• multiply our background image by (1-alpha channel)
• multiply our transparent image by alpha channel
• sum the two images.

We assume alpha channel has values 0-1.