opencv 图像基本操作

短命女 2023-08-17 16:29 63阅读 0赞

目录：读取图像，获取属性信息，图像ROI，图像通道的拆分和合并

**1.  读取图像**

像素值返回：直接使用坐标即可获得， 修改像素值：直接通过坐标进行赋值

能用矩阵操作，便用，使用numpy中的array.item()以及array.itemset()会加快速度，逐渐修改像素会慢

import cv2
    import numpy as np
    img = cv2.imread("test.jpg")
    #获取像素值
    px = img[100,100]
    blue = img[100,100,0]
    print(px, blue)
    #修改像素值
    img[100,100] = [255,255,255]
    print(img[100,100])
    #使用item
    print(img.item(10,10,2))
    img.itemset((10,10,2),100)
    print(img.item(10,10,2))

**2.  图像属性： 行、列、通道、数据类型、像素数目**

print(img.shape)
    #(342,548,3)   (342,548)  图像是灰度时，只有行和列
    print(img.size, img.dtype)
    #562248 uint8  图像像素数目， 图像数据类型，  注意：运行代码时数据类型是否一致

**3.  图像ROI**

ROI = img[y1:y2,x1:x2]

**4. 拆分以及合并图像通道**

b,g,r = cv2.split(img)
    img = cv2.merge(bgr)
    b = img[:,:,0]
    #修改时能尽量用numpy索引就用，用split比较耗时

**5.  图像加法及混合**

cv2.add(x, y)
    cv2.addWeighted(img1, 0.7, img2, 0.3, 0)   #dst = a* img1 + b*img2 + c

**6.  图像掩码**

import cv2
    import numpy as np
    # Load two images
    img1 = cv2.imread('messi5.jpg')
    img2 = cv2.imread('opencv-logo-white.png')
    
    # I want to put logo on top-left corner, So I create a ROI
    rows,cols,channels = img2.shape
    roi = img1[0:rows, 0:cols ]
    
    # Now create a mask of logo and create its inverse mask also
    img2gray = cv2.cvtColor(img2,cv2.COLOR_BGR2GRAY)
    ret, mask = cv2.threshold(img2gray, 10, 255, cv2.THRESH_BINARY)
    mask_inv = cv2.bitwise_not(mask)
    
    # Now black-out the area of logo in ROI
    img1_bg = cv2.bitwise_and(roi,roi,mask = mask_inv)
    
    # Take only region of logo from logo image.
    img2_fg = cv2.bitwise_and(img2,img2,mask = mask)
    
    # Put logo in ROI and modify the main image
    dst = cv2.add(img1_bg,img2_fg)
    img1[0:rows, 0:cols ] = dst
    
    cv2.imshow('res',img1)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

转载于:https://www.cnblogs.com/sword-/p/11344375.html