Question

我正在尝试将人脸识别与Raspberry pi3和pi相机配合使用。工作环境如下。

Python 2.7.13
Python3 3.5.3
scikit-learn 0.18
numpy 1.12.1
scipy 0.18.1
matplotlib 2.0.0
PIL(Pillow) 4.0.0
keras 2.2.0
theano 1.0.2

当我执行程序时，出现以下错误。在stackoverflow和其他站点上搜索错误时，有一种解决方案使用“ VideoCapture（1）”而不是“ VideoCapture（0）”，但是在我的情况下，它不起作用。然后，当我搜索有关“ libpng警告：IHDR中图像宽度为零”的错误时，有人建议插入time.sleep（）以等待相机启动。我尝试过，但是对我不起作用。

pi@raspberrypi:~/20180717_WebScrb $ python3 face_detection.py
Using Theano backend.
libpng warning: Image width is zero in IHDR
libpng warning: Image height is zero in IHDR
libpng error: Invalid IHDR data
OpenCV Error: Assertion failed (size.width>0 && size.height>0) in imshow, file /home/pi/opencv-3.4.0/modules/highgui/src/window.cpp, line 331
Traceback (most recent call last):
  File "face_detection.py", line 75, in <module>
    main()
  File "face_detection.py", line 63, in main
    cv2.imshow("Show FLAME Image", frame)
cv2.error: /home/pi/opencv-3.4.0/modules/highgui/src/window.cpp:331: error: (-215) size.width>0 && size.height>0 in function imshow

Python代码如下。

import face_keras as face
import sys, os
from keras.preprocessing.image import load_img, img_to_array
import numpy as np
import cv2
import time


cascade_path = "/usr/local/share/OpenCV/haarcascades/haarcascade_frontalface_alt.xml"
#cascade_path = "haarcascade_frontalface_alt.xml"
cascade = cv2.CascadeClassifier(cascade_path)
cam = cv2.VideoCapture(0)
color = (255, 255, 255)

image_size = 32
categories = ["obama", "trump"]

def main():
    while(True):
        ret, frame = cam.read()
        facerect = cascade.detectMultiScale(frame, scaleFactor=1.2, minNeighbors=2, minSize=(10, 10))
        cv2.imwrite("frontalface.png", frame)
        img = cv2.imread("frontalface.png")
        for rect in facerect:
            cv2.rectangle(frame, tuple(rect[0:2]),tuple(rect[0:2] + rect[2:4]), color, thickness=2)
            x = rect[0]
            y = rect[1]
            width = rect[2]
            height = rect[3]
            dst = img[y:y+height, x:x+width]
            cv2.imwrite("output.png", dst)
            cv2.imread("output.png")
            X = []

            img = load_img("./output.png", target_size=(image_size,image_size))
            in_data = img_to_array(img)

            X.append(in_data)
            X = np.array(X)
            X  = X.astype("float")  / 256

            model = face.build_model(X.shape[1:])
            model.load_weights("./image/face-model.h5")

            pre = model.predict(X)
            print(pre)
            if pre[0][0] > 0.9:
                print(categories[0])
                text = categories[0] + str(pre[0][0]*100) + "%"
                font = cv2.FONT_HERSHEY_PLAIN
                cv2.putText(frame,text,(rect[0],rect[1]-10),font, 2, color, 2, cv2.LINE_AA)
            elif pre[0][1] > 0.9:
                print(categories[1])
                text = categories[1] + str(pre[0][1]*100) + "%"
                font = cv2.FONT_HERSHEY_PLAIN
                cv2.putText(frame,text,(rect[0],rect[1]-10),font, 2, color, 2, cv2.LINE_AA)
            elif pre[0][2] > 0.9:
                print(categories[2])
                text = categories[2] + str(pre[0][2]*100) + "%"
                font = cv2.FONT_HERSHEY_PLAIN
                cv2.putText(frame,text,(rect[0],rect[1]-10),font, 2, color, 2, cv2.LINE_AA)

        cv2.imshow("Show FLAME Image", frame)
        time.sleep(0.4)

        k = cv2.waitKey(1)

        if k == ord('q'):
            break

    cam.release()
    cv2.destroyAllWindows()

if __name__ == '__main__':
    main()

我认为'cv2.imwrite（“ frontalface.png”，frame）'不起作用，因为它在当前文件夹中输出frontalface.png，但它是0字节（空）。很抱歉，这篇文章与某人的提问内容完全相同。但是，我自己尝试找不到。所以我在这里问你一个问题。

Answer 1

尝试测试dst [0]是否不等于0。请检查此更正，并告诉我它是否有效。

  dst = img[y:y+height, x:x+width]
  if dst[0].size > 0:
         cv2.imwrite("output.png", dst)

'libpng错误：无效的IHDR数据'和cpp：331：错误：（-215）size.width> 0 && size.height> 0在函数imshow中

1 个答案: