如何使用 opencv 和 dlib 检测前额区域？

Question

I want to detect the forehead region for research purposes.

I have tried taking the width of my roi as the distance between the leftmost point of the left eye and the rightmost point of the right eye. This seems to work as far as width is concerned however when it comes to height i need a solution that works for all people. Note i do not want hair to appear in my roi. I have an implementation of the height but it does not work for all people.

x = int((shape[21][0]+shape[22][0])/2)
y = int((shape[21][1]+shape[22][1])/2)
w = abs(shape[39][0]-shape[42][0])
h = abs(y-shape[29][1])

y_mid = int((y + (y - h)) / 2)
roi = image[y-h:y_mid,int(x-w/2):int(x+w/2)]

if(roi.shape[0] !=0 and roi.shape[1] != 0):
    roi = imutils.resize(roi, width=250, inter=cv2.INTER_CUBIC)
    cv2.imshow('ROI', roi)

cv2.rectangle(image,(int(x-w/2), int(y-h)), (int(x + w/2), y_mid), (0, 0, 255), 1)
cv2.imshow('Image', image)

Answer 1

Code for detecting forehead :

import face_recognition
import cv2
import PIL.Image
import PIL.ImageDraw
import os
#image=cv2.imread(img_path)
unknown_image = face_recognition.load_image_file("16.png")
face_locations = face_recognition.face_locations(unknown_image) # detects all the faces in image
t = len(face_locations)
print(len(face_locations))
print(face_locations)
face_landmarks_list = face_recognition.face_landmarks(unknown_image)
# Drawing rectangles over the faces
pil_image = PIL.Image.fromarray(unknown_image)
for face_location in face_locations:
    #print(face_location)
    top,right,bottom,left =face_location
    draw_shape = PIL.ImageDraw.Draw(pil_image)
    im = PIL.Image.open("16.png")
    #bottom=34
    k = face_landmarks_list[0]['right_eyebrow']
    bottom= face_landmarks_list[0]['right_eyebrow'][0][1]
    for k1 in k :   
        if(bottom>k1[1]):
            bottom=k1[1]
    k = face_landmarks_list[0]['left_eyebrow']
    lbottom= face_landmarks_list[0]['left_eyebrow'][0][1]
    for k1 in k :   
        if(lbottom>k1[1]):
            lbottom=k1[1]
    bottom=min(bottom,lbottom)
    print(bottom)
    im = im.crop((left, top, right, bottom))
    im.save("m2.jpg")    
    draw_shape.rectangle([left, top, right, bottom],outline="blue")