目的

• 分享學(xué)習(xí)心得，從實操中學(xué)習(xí)圖像的前處理。代碼直接跑，什么都不用改，如果網(wǎng)址失效，直接換網(wǎng)址即可。

庫

- imageio==2.6.0 用來讀取網(wǎng)址圖片 - cv2==3.2.14 圖像操作 - numpy==1.19.0

• 獲取圖片

import imageio # 可以從網(wǎng)址中讀取圖片的庫 --> pip install imageio import cv2 file_path = "http://img.mp.itc.cn/upload/20170206/3cbd5b8834df4b409d289d9d8d50530a_th.jpg" img = imageio.imread(file_path) img = cv2.cvtColor(img,cv2.COLOR_RGB2BGR) # 讀取的是RGB通道，轉(zhuǎn)成opencv的BGR通過 cv2.imwrite("cat.jpg",img ) cv2.imshow("cat", img) cv2.waitKey(0) cv2.destroyAllWindows()

• 圖片分通道

# 圖片分通道 -->B,G,R import imageio import cv2 file_path = "http://img.mp.itc.cn/upload/20170206/3cbd5b8834df4b409d289d9d8d50530a_th.jpg" img = imageio.imread(file_path) img = cv2.cvtColor(img,cv2.COLOR_RGB2BGR) # 讀取的是RGB通道，轉(zhuǎn)成opencv的BGR通道 img = cv2.resize(img,(360,640)) # 更改大小，便于顯示 b,g,r = cv2.split(img) # 圖片分通道 # img_1 = cv2.merge((b, g, r)) # 分割后的通道合并 bgr = np.hstack((b,g,r)) # 圖片矩陣并排顯示 cv2.imwrite("split.jpg",bgr ) cv2.imshow("split",bgr) cv2.waitKey(0) cv2.destroyAllWindows()

• 形態(tài)學(xué)——腐蝕膨脹

import imageio import cv2 file_path = "http://1824.img.pp.sohu.com.cn/images/blog/2009/7/21/21/16/1234ab28e28g214.jpg" img = imageio.imread(file_path) img = cv2.cvtColor(img,cv2.COLOR_RGB2BGR) kernel = (7,7) # 腐蝕或膨脹的程度 erode = cv2.erode(img, kernel, iterations=20) # 腐蝕操作 dilate = cv2.dilate(img, kernel, iterations=20) # 膨脹操作 result = np.hstack((img,erode,dilate)) # 原圖 - 腐蝕 - 膨脹 cv2.imwrite("erode_dilate.jpg",result) cv2.imshow("result",result) cv2.waitKey(0) cv2.destroyAllWindows()

• 形態(tài)學(xué)——開運算，閉運算

import numpy as np import imageio import cv2 file_path = "https://img.pconline.com.cn/images/photoblog/9/7/3/6/9736422/20099/21/1253523872358_mthumb.jpg" img = imageio.imread(file_path) img = cv2.cvtColor(img,cv2.COLOR_RGB2BGR) img = cv2.resize(img,(360,360)) kernel = (7,7) # 腐蝕或膨脹的程度 opens = cv2.morphologyEx(img, cv2.MORPH_OPEN, kernel, iterations=20) # 開運算 -->先腐蝕再膨脹 close = cv2.morphologyEx(img, cv2.MORPH_CLOSE, kernel, iterations=20) # 閉運算 -->先膨脹再腐蝕 result = np.hstack((img,opens,close)) # 原圖 - 開運算 - 閉運算 cv2.imwrite("open_close.jpg",result) cv2.imshow("result",result) cv2.waitKey(0) cv2.destroyAllWindows()

• 邊緣檢測——sobel

import numpy as np import imageio import cv2 file_path = "http://img.mp.itc.cn/upload/20170206/3cbd5b8834df4b409d289d9d8d50530a_th.jpg" img = imageio.imread(file_path) img = cv2.cvtColor(img,cv2.COLOR_RGB2BGR) img = cv2.resize(img,(360,640)) sobelx = cv2.Sobel(img, ddepth=cv2.CV_32F, dx=1, dy=0, ksize=3) # 延x方向檢測 sobely = cv2.Sobel(img, ddepth=cv2.CV_32F, dx=0, dy=1, ksize=3) # 延y方向檢測 # sobelxy = cv2.Sobel(img, ddepth=cv2.CV_32F, dx=1, dy=1, ksize=3) # 也可以直接x-y一起sobel，但一般效果沒有分開處理的好 convx = cv2.convertScaleAbs(sobelx) # convy = cv2.convertScaleAbs(sobely) sobel = cv2.addWeighted(convx, 0.5, convy, 0.5, 0) res = np.hstack((img, convx, convy, sobel)) # 原圖 - sobelx - sobely - sobel cv2.imwrite("sobel.jpg",res) cv2.imshow('res', res) cv2.waitKey(0) cv2.destroyAllWindows()

• 邊緣檢測——canny

import numpy as np import imageio import cv2 file_path = "http://img.mp.itc.cn/upload/20170206/3cbd5b8834df4b409d289d9d8d50530a_th.jpg" img = imageio.imread(file_path) img = cv2.cvtColor(img,cv2.COLOR_RGB2BGR) img = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY) img = cv2.resize(img,(360,640)) print(img.shape) # thresh1和thresh2可以根據(jù)實際圖片情況更改 thresh1 = 0 thresh2 = 125 canny = cv2.Canny(img, thresh1, thresh2) print(canny.shape) result = np.hstack((img,canny)) cv2.imwrite("canny.jpg",result) cv2.imshow('res', result) cv2.waitKey(0) cv2.destroyAllWindows()

• 圖像金字塔

# 上采樣 import numpy as np import imageio import cv2 file_path = "http://img.mp.itc.cn/upload/20170206/3cbd5b8834df4b409d289d9d8d50530a_th.jpg" original = imageio.imread(file_path) img = cv2.cvtColor(original,cv2.COLOR_RGB2BGR) # 下采樣 down1 = cv2.pyrDown(img,(int(img.shape[0]/2),int(img.shape[1]/2))) down2 = cv2.pyrDown(down1,(int(img.shape[0]/4),int(img.shape[1]/4))) # # 上采樣 # up1 = cv2.pyrUp(img,(int(img.shape[0]/2),int(img.shape[1]/2))) # up2 = cv2.pyrUp(up1 ,(int(img.shape[0]/4),int(img.shape[1]/4))) cv2.imwrite("original.jpg",img) cv2.imwrite("down1.jpg",down1) cv2.imwrite("down2.jpg",down2) cv2.imshow('original',img) cv2.imshow('down1',down1) cv2.imshow('down2',down2) cv2.waitKey(0) cv2.destroyAllWindows()

• 總結(jié)
  • 每天進步一點點
• 參考文獻
  https://max.book118.com/html/2018/0523/168182943.shtm

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