Python | OpenCV 圖片合成、疊加與相減

import cv2

# 讀取三張圖片
img1 = cv2.imread("red.png")
img2 = cv2.imread("green.png")
img3 = cv2.imread("blue.png")

# 確保大小一致
img2 = cv2.resize(img2, (img1.shape[1], img1.shape[0]))
img3 = cv2.resize(img3, (img1.shape[1], img1.shape[0]))

# 先合成前兩張
temp = cv2.add(img1, img2)

# 再把結果與第三張合成
output = cv2.add(temp, img3)

cv2.imshow("Red", img1)
cv2.imshow("Green", img2)
cv2.imshow("Blue", img3)
cv2.imshow("Add Result", output)
cv2.waitKey(0)
cv2.destroyAllWindows()

import cv2

img1 = cv2.imread("test.png")  # 部落格頭像
img2 = cv2.imread("OpenCV_logo_black.png")

img2 = cv2.resize(img2, (img1.shape[1], img1.shape[0]))

output = cv2.addWeighted(img1, 0.8, img2, 0.2, 0)

cv2.imshow("Weighted Blend", output)
cv2.waitKey(0)
cv2.destroyAllWindows()

import cv2

# 讀取圖片
img1 = cv2.imread("white_green.png")   # 白色 + 綠色重疊的圖
img2 = cv2.imread("yellow.png")        # 黃色圓形的圖

# 確保大小一致
img2 = cv2.resize(img2, (img1.shape[1], img1.shape[0]))

# 相減
output = cv2.subtract(img1, img2)

# 顯示結果
cv2.imshow("Image A (White+Green)", img1)
cv2.imshow("Image B (Yellow)", img2)
cv2.imshow("Subtract Result", output)
cv2.waitKey(0)
cv2.destroyAllWindows()

import cv2
import numpy as np

# 讀取 logo 與背景 (保持原始大小)
logo = cv2.imread("OpenCV_logo_black.png")
bg   = cv2.imread("test.png")

# 建立灰階遮罩
logo_gray = cv2.cvtColor(logo, cv2.COLOR_BGR2GRAY)

# 建立兩個遮罩：一個保留 logo，一個保留背景
# 白色區域灰階值很高，設定閾值 240
_, mask_logo = cv2.threshold(logo_gray, 240, 255, cv2.THRESH_BINARY_INV)  # 保留非白色區域 (logo)
_, mask_bg   = cv2.threshold(logo_gray, 240, 255, cv2.THRESH_BINARY)      # 保留白色區域 (背景)

# 去背：只保留 logo 部分
logo_no_bg = cv2.bitwise_and(logo, logo, mask=mask_logo)

# 建立 ROI (放置 logo 的區域)
# 這裡假設 logo 要放在背景左上角 (0:logo.shape[0], 0:logo.shape[1])
rows, cols = logo.shape[:2]
roi = bg[0:rows, 0:cols]

# 清空 ROI 中 logo 的位置
bg_roi = cv2.bitwise_and(roi, roi, mask=mask_bg)

# 合成：背景 ROI + logo
dst = cv2.add(bg_roi, logo_no_bg)
bg[0:rows, 0:cols] = dst

# 顯示結果
cv2.imshow("Logo Merge Result", bg)
cv2.waitKey(0)
cv2.destroyAllWindows()