A simple pedestrian detector based on PyImageSearch's blogpost

pedestrian-detector.py

import numpy as np
import cv2
from imutils.object_detection import non_max_suppression
from imutils import paths
import argparse
import imutils

"""
The parameters passed to the hog detector need to be played around
with to get optimum speed vs accuracy. This will always be a tradeoff.
"""
def detect_people(hog, image):

    orig = image.copy()
    # detect people in the image
    (rects, weights) = hog.detectMultiScale(image, winStride=(4, 4),
        padding=(8, 8), scale=1.05)

    # draw the original bounding boxes
    for (x, y, w, h) in rects:
        cv2.rectangle(orig, (x, y), (x + w, y + h), (0, 0, 255), 2)

    # apply non-maxima suppression to the bounding boxes using a
    # fairly large overlap threshold to try to maintain overlapping
    # boxes that are still people
    rects = np.array([[x, y, x + w, y + h] for (x, y, w, h) in rects])
    pick = non_max_suppression(rects, probs=None, overlapThresh=0.65)

    # draw the final bounding boxes
    for (xA, yA, xB, yB) in pick:
        cv2.rectangle(image, (xA, yA), (xB, yB), (0, 255, 0), 2)

    # # show some information on the number of bounding boxes
    # filename = imagePath[imagePath.rfind("/") + 1:]
    # print("[INFO] {}: {} original boxes, {} after suppression".format(
    #     filename, len(rects), len(pick)))

def open_cam_and_detect(path):
    cap = cv2.VideoCapture(path)
    
    # initialize the HOG descriptor/person detector
    hog = cv2.HOGDescriptor()
    hog.setSVMDetector(cv2.HOGDescriptor_getDefaultPeopleDetector())

    if not cap.isOpened():
    	raise AssertionError('Cap not opened')

    while(True):
        # Capture frame-by-frame
        ret, frame = cap.read()
        if not ret:
    		raise AssertionError('Cap not opened')

        # Our operations on the frame come here
        # gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

        detect_people(hog, frame)

        # Display the resulting frame
        cv2.imshow('frame',frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

    # When everything done, release the capture
    cap.release()
    cv2.destroyAllWindows()

if __name__ == '__main__':
    open_cam_and_detect(0) # uses webcam
    open_cam_and_detect('/home/rish/Desktop/temp.mp4') # uses file stored