python+opencv+图像特效（图像灰度处理、颜色翻转、图片融合，边缘检测，浮雕效果，颜色映射）

原图

图像灰度处理

#方式1
import cv2
#读取彩色原图
img0=cv2.imread('E:/python_cv/01.jpg',1)
#读取灰度图
img1=cv2.imread('E:/python_cv/01.jpg',0)
print(img0.shape)
print(img1.shape)
cv2.imshow('gary',img1)
cv2.waitKey(0)

#方式2
import cv2
#读取彩色原图
src=cv2.imread('E:/python_cv/01.jpg',1)
dst=cv2.cvtColor(src,cv2.COLOR_BGR2GRAY)
cv2.imshow('gary',dst)
cv2.waitKey(0)

#方式3
import cv2
import numpy as np
img=cv2.imread('E:/python_cv/01.jpg',1)
img_info=img.shape
image_height=img_info[0]
image_weight=img_info[1]
dst=np.zeros((image_height,image_weight,3),np.uint8)
#当彩色图像三个通道的值都相同时，即为灰度图像
for i in range(image_height):
    for j in range(image_weight):
        (b,g,r)=img[i][j]
        gray=(int(b)+int(g)+int(r))/3  #防止越界，转换类型
        dst[i,j]=np.uint8(gray)
cv2.imshow('gary',dst)
cv2.waitKey(0)

#方式4
import cv2
import numpy as np
img=cv2.imread('E:/python_cv/01.jpg',1)
img_info=img.shape
image_height=img_info[0]
image_weight=img_info[1]
dst=np.zeros((image_height,image_weight,3),np.uint8)
#当彩色图像三个通道的值都相同时，即为灰度图像
for i in range(image_height):
    for j in range(image_weight):
        (b,g,r)=img[i][j]
        gray=0.299*int(b)+0.587*int(g)+0.114*int(r)
        dst[i,j]=np.uint8(gray)
cv2.imshow('gary',dst)
cv2.waitKey(0)

灰度处理很重要，也是图像处理中的基础操作，在实际运用中要求实时性，涉及优化，比如：

• 定点操作比浮点操作要快
• +-比*/快，移位比*/快

import cv2
import numpy as np
img=cv2.imread('E:/python_cv/01.jpg',1)
img_info=img.shape
image_height=img_info[0]
image_weight=img_info[1]
dst=np.zeros((image_height,image_weight,3),np.uint8)
#当彩色图像三个通道的值都相同时，即为灰度图像
for i in range(image_height):
    for j in range(image_weight):
        (b,g,r)=img[i][j]
        # gray=0.299*int(b)+0.587*int(g)+0.114*int(r)
        #优化
        b=int(b)
        g=int(g)
        r=int(r)
        # gray=(b+2*g+r)/4
        gray=(b+(g<<1)+r)>>2
        dst[i,j]=np.uint8(gray)
cv2.imshow('gary',dst)
cv2.waitKey(0)

颜色翻转

灰度图像素值为0到255，若当前的像素值为i,翻转过后为255-i

import cv2
import numpy as np
#读取彩色原图
src=cv2.imread('E:/python_cv/01.jpg',1)
gray=cv2.cvtColor(src,cv2.COLOR_BGR2GRAY)
img_info=src.shape
image_height=img_info[0]
image_weight=img_info[1]
dst=np.zeros((image_height,image_weight,1),np.uint8)
for i in range(image_height):
    for j in range(image_weight):
        grayPixel=gray[i][j]
        dst[i][j]=255-grayPixel
cv2.imshow('gary',dst)
cv2.waitKey(0)

原灰度图	反转灰度图

彩色图反转

import cv2
import numpy as np
#读取彩色原图
src=cv2.imread('E:/python_cv/01.jpg',1)
img_info=src.shape
image_height=img_info[0]
image_weight=img_info[1]
dst=np.zeros((image_height,image_weight,3),np.uint8)
for i in range(image_height):
    for j in range(image_weight):
        (b,g,r)=src[i][j]
        dst[i][j]=(255-b,255-g,255-r)
cv2.imshow('src',src)
cv2.imshow('dst',dst)
cv2.waitKey(0)

彩色图	反转图

图片融合

import cv2
import numpy as np
#读取彩色原图
src=cv2.imread('E:/python_cv/01.jpg',1)
src1=cv2.imread('E:/python_cv/02.jpg',1)
img_info=src.shape
image_height=img_info[0]
image_weight=img_info[1]
roi_h=int(image_height/2)
roi_w=int(image_weight/2)
src_roi=src[0:roi_h,0:roi_w]
src1_roi=src1[0:roi_h,0:roi_w]
dst=np.zeros((roi_h,roi_w,3),np.uint8)
dst=cv2.addWeighted(src_roi,0.5,src1_roi,0.5,0)

cv2.imshow('dst',dst)
cv2.waitKey(0)

canny 边缘检测

步骤：灰度图，高斯滤波，canny

import cv2
import numpy as np
gray=cv2.imread('E:/python_cv/01.jpg',0)
img=cv2.GaussianBlur(gray,(3,3),0)
dst=cv2.Canny(img,50,50)
cv2.imshow('gray',gray)
cv2.imshow('gauss',img)
cv2.imshow('dst',dst)
cv2.waitKey(0)

灰度图	高斯滤波	canny

soble边缘检测

import cv2
import numpy as np
import math
gray=cv2.imread('E:/python_cv/01.jpg',0)
imgInfo=gray.shape
height=imgInfo[0]
weight=imgInfo[1]
cv2.imshow('src',gray)
dst=np.zeros((height,weight,1),np.uint8)
'''
sobel
1.算子模板 2.图像卷积 3.阈值判决
竖直模板      水平模板
[1 2 1       [1 0 -1
 0 0 0        2 0 -2
-1-2-1]       1 0 -1]
'''
for i in range(0,height-2):
    for j in range(0,weight-2):
        gy=gray[i,j]*1+gray[i,j+1]*2+gray[i,j+2]*1-gray[i+2,j]-2*gray[i+2,j+1]-gray[i+2,j+2]*1
        gx=gray[i,j]*1-gray[i,j+2]+gray[i+1,j]*2-2*gray[i+1,j+2]+gray[i+2,j]-gray[i+2,j+2]
        grad=math.sqrt(gx*gx+gy*gy)
        if grad>50:
            dst[i,j]=255
        else:
            dst[i,j]=0
cv2.imshow('dst',dst)
cv2.waitKey(0)

原图	sobel

import cv2
import numpy as np
gray=cv2.imread('E:/python_cv/01.jpg',0)
imgInfo=gray.shape
height=imgInfo[0]
weight=imgInfo[1]
#浮雕效果
dst=np.zeros((height,weight,1),np.uint8)
for i in range(0,height):
    for j in range(0,weight-1):
        gray0=gray[i,j]
        gray1=gray[i,j+1]
        newp=gray0-gray1+150
        if newp>255:
            newp=255
        else:
            newp=0
        dst[i,j]=newp
cv2.imshow('dst',dst)
cv2.waitKey(0)

原图	浮雕效果

风格转换

import cv2
import numpy as np
img=cv2.imread('E:/python_cv/01.jpg',1)
imgInfo=img.shape
height=imgInfo[0]
weight=imgInfo[1]
cv2.imshow('src',img)
'''
颜色风格，rgb-->RGB
b=b*1.5
g=g*1.3
'''
dst=np.zeros((height,weight,3),np.uint8)
for i in range(0,height):
    for j in range(0,weight):
        (b,g,r)=img[i,j]
        b=1.5*b
        g=1.3*g
        if b>255:
            b=255
        if g>255:
            g=255
        dst[i,j]=(b,g,r)
cv2.imshow('dst',dst)
cv2.waitKey(0)

原图	颜色风格