树莓派上的OpenCV人脸检测速度较慢

Question

树莓派上的OpenCV人脸检测速度较慢

7

我正在使用OpenCV和Python代码测试树莓派。视频流传输工作正常（中等速度），但当我在流上运行人脸检测时，CPU占用率很高，刷新图像很慢。

这是我的代码。我应该如何优化它？

#!/usr/bin/env python
import sys
import cv2.cv as cv
from optparse import OptionParser
min_size = (20, 20)
image_scale = 2
haar_scale = 1.2
min_neighbors = 2
haar_flags = 0

def detect_and_draw(img, cascade):
    # allocate temporary images
    gray = cv.CreateImage((img.width,img.height), 8, 1)
    small_img = cv.CreateImage((cv.Round(img.width / image_scale),
                               cv.Round (img.height / image_scale)), 8, 1)
                               cv.Round (img.height / image_scale)), 8, 1)

    # convert color input image to grayscale
    cv.CvtColor(img, gray, cv.CV_BGR2GRAY)

    # scale input image for faster processing
    cv.Resize(gray, small_img, cv.CV_INTER_LINEAR)

    cv.EqualizeHist(small_img, small_img)

    if(cascade):
        t = cv.GetTickCount()
        faces = cv.HaarDetectObjects(small_img, cascade, cv.CreateMemStorage(0),
                                     haar_scale, min_neighbors, haar_flags, min_size)
        t = cv.GetTickCount() - t
        print "detection time = %gms" % (t/(cv.GetTickFrequency()*1000.))
        if faces:
            for ((x, y, w, h), n) in faces:
                # the input to cv.HaarDetectObjects was resized, so scale the 
                # bounding box of each face and convert it to two CvPoints
                pt1 = (int(x * image_scale), int(y * image_scale))
                # bounding box of each face and convert it to two CvPoints
                pt1 = (int(x * image_scale), int(y * image_scale))
                pt2 = (int((x + w) * image_scale), int((y + h) * image_scale))
                cv.Rectangle(img, pt1, pt2, cv.RGB(255, 0, 0), 3, 8, 0)

    cv.ShowImage("result", img)

if __name__ == '__main__':

    parser = OptionParser(usage = "usage: %prog [options] [camera_index]")
    parser.add_option("-c", "--cascade", action="store", dest="cascade", type="str", help="Haar cascade file, default %default", default = "/usr/local/share/OpenCV/haarcascades")
    (options, args) = parser.parse_args()

    cascade = cv.Load(options.cascade)
    capture = cv.CreateCameraCapture(0)
    cv.NamedWindow("result", 1)

    if capture:
        frame_copy = None
        while True:
            frame = cv.QueryFrame(capture)
            if not frame:
                cv.WaitKey(0)
                break
            if not frame_copy:
                frame_copy = cv.CreateImage((frame.width,frame.height),
                                            cv.IPL_DEPTH_8U, frame.nChannels)
            if frame.origin == cv.IPL_ORIGIN_TL:
                cv.Copy(frame, frame_copy)
            else:
                cv.Copy(frame, frame_copy)
            else:
                cv.Flip(frame, frame_copy, 0)

            detect_and_draw(frame_copy, cascade)

            if cv.WaitKey(10) != -1:
                break
    else:
        image = cv.LoadImage(input_name, 1)
        detect_and_draw(image, cascade)
        cv.WaitKey(0)

    cv.DestroyWindow("result")

- honeyshell

你的 parser.add_option 行代码被截断了，我想。 - Martijn Pieters

是的，没错。但这不是我问题的重点。 - honeyshell

2

我从未说过它是。 :-) 只是给你纠正的机会；我已经关闭了字符串和括号。 - Martijn Pieters

1个回答

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- Andrey Kamaev · Accepted Answer

我可以建议您使用LBP级联代替Haar。它已知在非常接近的检测率下，速度可快达6倍。

但我不确定它是否在旧版Python接口中可用。新包装器中的cv2.CascadeClassifier类可以为LBP级联执行检测。