import cv2
import numpy as np

img = cv2.imread("Resources/The Legend of Zelda.jpg")
kernel = np.ones((5, 5), np.uint8)  # 卷積核

# 顏色空間轉換，轉換成灰度圖(注意是BGR而不是RBG)
imgGray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
# 平滑處理，高斯模糊, 高斯核的寬和高只能是奇數
imgBlur = cv2.GaussianBlur(imgGray, (5, 5), 0)
# 邊緣檢測, 實際也是採用了高斯模糊去除噪音並設定梯度閾值進行過濾
imgCanny = cv2.Canny(img, 150, 200)
# 膨脹，可以適當增加迭代次數
imgDilated = cv2.dilate(imgCanny, kernel, iterations=1)
# 侵蝕
imgEroded = cv2.erode(imgDilated, kernel, iterations=1)

# 縮小到0.2倍並拼接
imgStack = stackImages(0.2, [[img, imgGray, imgBlur],
                             [imgCanny, imgDilated, imgEroded]])
cv2.imshow("Image Stack", imgStack)

cv2.waitKey(0)

其中stackImage函式的定義為

def stackImages(scale, imgArray):
    '''
    影象堆疊，可縮放，按列表排列，不受顏色通道限制
    '''
    rows = len(imgArray)
    cols = len(imgArray[0])
    rowsAvailable = isinstance(imgArray[0], list)
    width = imgArray[0][0].shape[1]
    height = imgArray[0][0].shape[0]
    if rowsAvailable:
        for x in range(0, rows):
            for y in range(0, cols):
                if imgArray[x][y].shape[:2] == imgArray[0][0].shape[:2]:
                    imgArray[x][y] = cv2.resize(imgArray[x][y], (0, 0), None, scale, scale)
                else:
                    imgArray[x][y] = cv2.resize(imgArray[x][y], (imgArray[0][0].shape[1], imgArray[0][0].shape[0]),
                                                None, scale, scale)
                if len(imgArray[x][y].shape) == 2:
                    imgArray[x][y] = cv2.cvtColor(imgArray[x][y], cv2.COLOR_GRAY2BGR)
        imageBlank = np.zeros((height, width, 3), np.uint8)
        hor = [imageBlank]*rows
        hor_con = [imageBlank]*rows
        for x in range(0, rows):
            hor[x] = np.hstack(imgArray[x])
        ver = np.vstack(hor)
    else:
        for x in range(0, rows):
            if imgArray[x].shape[:2] == imgArray[0].shape[:2]:
                imgArray[x] = cv2.resize(imgArray[x], (0, 0), None, scale, scale)
            else:
                imgArray[x] = cv2.resize(imgArray[x], (imgArray[0].shape[1], imgArray[0].shape[0]), None,scale, scale)
            if len(imgArray[x].shape) == 2:
                imgArray[x] = cv2.cvtColor(imgArray[x], cv2.COLOR_GRAY2BGR)
        hor = np.hstack(imgArray)
        ver = hor
    return ver

封裝了numpy中的vstack和hstack，方便使用

效果:

更多影象處理可參考官方文件：https://docs.opencv.org/master/d2/d96/tutorial_py_table_of_contents_imgproc.html