opencv 彩色图(24位)转灰色图(8位)

绝地灬酷狼 2021-11-17 13:10 515阅读 0赞

1，彩色图转灰度图：

#方法2 cvtColor
    import cv2
    img = cv2.imread('image0.jpg',1)
    #第一个参数是读取到的图像数据，第二个则是转换格式cv2.COLOR_BGR2GRAY（彩色图转灰度图）
    dst = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)# 颜色空间转换 1 data 2 BGR gray
    cv2.imshow('dst',dst)
    cv2.waitKey(0)

2，实现方法二：

import cv2
    import numpy as np
    img = cv2.imread('image0.jpg',1)
    imgInfo = img.shape
    height = imgInfo[0]
    width = imgInfo[1]
    # RGB R=G=B = gray  (R+G+B)/3
    dst = np.zeros((height,width,3),np.uint8) #np.uint8表示数据类型
    for i in range(0,height):
        for j in range(0,width):
            (b,g,r) = img[i,j]
            gray = (int(b)+int(g)+int(r))/3
            dst[i,j] = np.uint8(gray)
    cv2.imshow('dst',dst)
    cv2.waitKey(0)

3,彩色图和灰度图的转换：

#gray = r*0.299+g*0.587+b*0.114
    import cv2
    import numpy as np
    img = cv2.imread('image0.jpg',1)
    imgInfo = img.shape
    height = imgInfo[0]
    width = imgInfo[1]
    dst = np.zeros((height,width,3),np.uint8)
    for i in range(0,height):
        for j in range(0,width):
            (b,g,r) = img[i,j]
            b = int(b)
            g = int(g)
            r = int(r)
            gray = r*0.299+g*0.587+b*0.114
            dst[i,j] = np.uint8(gray)
    cv2.imshow('dst',dst)
    cv2.waitKey(0)

4，算法优化：

# 1 灰度 最重要 2 基础 3 实时性 
    # 定点-》浮点 +- */ >> 
    # r*0.299+g*0.587+b*0.114
    import cv2
    import numpy as np
    img = cv2.imread('image0.jpg',1)
    imgInfo = img.shape
    height = imgInfo[0]
    width = imgInfo[1]
    # RGB R=G=B = gray  (R+G+B)/3
    dst = np.zeros((height,width,3),np.uint8)
    for i in range(0,height):
        for j in range(0,width):
            (b,g,r) = img[i,j]
            b = int(b)
            g = int(g)
            r = int(r)
            #
            #gray = (r*1+g*2+b*1)/4
            gray = (r+(g<<1)+b)>>2
            dst[i,j] = np.uint8(gray)
    cv2.imshow('dst',dst)
    cv2.waitKey(0)