import cv2

from PIL import Image,ImageDraw

import os 

def detectFaces(image_name):

    img = cv2.imread(image_name)

    face_cascade = cv2.CascadeClassifier('../opencv-2.4.9/data/haarcascades/haarcascade_frontalface_default.xml')

    if img.ndim==3: # 如果是三维就转换成二维

        gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

    else:

        gray = img

    faces = face_cascade.detectMultiScale(gray,scaleFactor = 1.3,minNeighbors=4)

    result = []

    for (x,y,width,height) in faces:

        result.append((x,y,x+width,y+height))

    return result

def saveFaces(image_name):

    faces = detectFaces(image_name)

    if faces:

        save_dir = image_name.split('.')[0]+"_faces"

        os.mkdir(save_dir)

        count = 0

        for (x1,y1,x2,y2) in faces:

            file_name = os.path.join(save_dir,str(count)+".jpg")

            Image.open(image_name).crop((x1,y1,x2,y2)).save(file_name)

            count +=1

#在原图像上画矩形，框出所有人脸。

#调用Image模块的draw方法，Image.open获取图像句柄， ImageDraw获取该图像的draw实例，然后调用该draw实例的rectangle方法画矩形 (矩形的坐标即mZdetectFaces返回的坐标)，outline是矩

形线条颜色(B,G,R)。

#注：原始图像如果是灰度图，则去掉outline，因为灰度图没有RGB可言。drawEyes、detectSmiles也一样

def drawFaces(image_name):

    faces = detectFaces(image_name)

    if faces:

        img = Image.open(image_name)

        draw_instance = ImageDraw.Draw(img)

        for(x1,y1,x2,y2) in faces:

            draw_instance.rectangle((x1,y1,x2,y2),outline=(25,255,0))

        img.save('drawFaces_'+image_name)

        saveFaces(image_name)

        image = cv2.imread('drawFaces_'+image_name)

        return image

if __name__=="__main__":

    img = drawFaces('obama.jpg')

    cv2.imshow("drawFaces",img)

    cv2.waitKey(0)

    cv2.destroyAllWindows()