faceRecog.py

#recognise faces using some classification algorithm -KNN ,Logistic regression

#1. Read a video stream using open cv
#2. Extract faces out of it
#3. Load training data (numpy arrays of all persons)
    #x -values are stored in numpy arrays
    #y- values we need to assign for each person
#4. useing K-NN to find prediction of the user
#5. map the predicted id to the name of the user
#6. Display the predictions ont the screen


import numpy as np
import cv2
import os

########## KNN CODE ############
def distance(v1, v2):
	# Eucledian 
	return np.sqrt(((v1-v2)**2).sum())

def knn(train, test, k=5):
	dist = []
	
	for i in range(train.shape[0]):
		# Get the vector and label
		ix = train[i, :-1]
		iy = train[i, -1]
		# Compute the distance from test point
		d = distance(test, ix)
		dist.append([d, iy])
	# Sort based on distance and get top k
	dk = sorted(dist, key=lambda x: x[0])[:k]
	# Retrieve only the labels
	labels = np.array(dk)[:, -1]
	
	# Get frequencies of each label
	output = np.unique(labels, return_counts=True)
	# Find max frequency and corresponding label
	index = np.argmax(output[1])
	return output[0][index]



    #init camera
cap = cv2.VideoCapture(0)

#face detection
face_cascade = cv2.CascadeClassifier("haarcascade_frontalface_alt.xml")

skip = 0
dataset_path = './data/'

face_data = []
labels = []

class_id = 0  #Labels for given file

names = {}  #Mapping btw id-name



#data prepration

for fx in os.listdir(dataset_path):
    if fx.endswith('.npy'):
        #mapping btw class id and name
        names[class_id] = fx[:-4]
        print(fx)
        data_item = np.load(dataset_path+fx)
        face_data.append(data_item)

        #Create labels for the class

        target = class_id*np.ones((data_item.shape[0],))
        class_id +=1
        labels.append(target)


face_dataset = np.concatenate(face_data,axis=0)

face_labels = np.concatenate(labels,axis=0).reshape((-1,1))

print(face_dataset.shape)
print(face_labels.shape)

trainset = np.concatenate((face_dataset,face_labels),axis=1)

print(trainset.shape)


#Testing the face Recog

while True:
	ret,frame = cap.read()
	if ret == False:
		continue

	faces = face_cascade.detectMultiScale(frame,1.3,5)
	if(len(faces)==0):
		continue

	for face in faces:
		x,y,w,h = face

		#Get the face ROI
		offset = 10
		face_section = frame[y-offset:y+h+offset,x-offset:x+w+offset]
		face_section = cv2.resize(face_section,(100,100))

		#Predicted Label (out)
		out = knn(trainset,face_section.flatten())

		#Display on the screen the name and rectangle around it
		pred_name = names[int(out)]
		cv2.putText(frame,pred_name,(x,y-10),cv2.FONT_HERSHEY_SIMPLEX,1,(255,0,0),2,cv2.LINE_AA)
		cv2.rectangle(frame,(x,y),(x+w,y+h),(0,255,255),2)

	cv2.imshow("Faces",frame)

	key = cv2.waitKey(1) & 0xFF
	if key==ord('q'):
		break

cap.release()
cv2.destroyAllWindows()