Python影像辨識筆記(一)：使用Open CV辨識圖片及影片中的人臉

Yanwei Liu

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Apr 25, 2019

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圖片人臉

安裝模組

pip install opencv-python

偵測人臉

import cv2# 載入分類器
face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')# 讀取圖片
img = cv2.imread('a.jpg')# 轉成灰階圖片
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)# 偵測臉部faces = face_cascade.detectMultiScale(
    gray,
    scaleFactor=1.08,
    minNeighbors=5,
    minSize=(32, 32))# 繪製人臉部份的方框
for (x, y, w, h) in faces:
    cv2.rectangle(img, (x, y), (x + w, y + h), (0, 255, 0), 2)#(0, 255, 0)欄位可以變更方框顏色(Blue,Green,Red)# 顯示成果
cv2.namedWindow('img', cv2.WINDOW_NORMAL)  #正常視窗大小
cv2.imshow('img', img)                     #秀出圖片
cv2.imwrite( "result.jpg", img )           #保存圖片
cv2.waitKey(0)                             #等待按下任一按鍵
cv2.destroyAllWindows()                    #關閉視窗

• scaleFactor: Parameter specifying how much the image size is reduced at each image scale. Increasing it leads to faster detection with the risk of missing some objects, whereas a small value might sometimes be too thorough.
• minNeighbors: Parameter specifying how many neighbors each candidate rectangle should have to retain…