用SVM+HOG识别图片错误

用SVM+HOG识别图片出现错误： error: (-215:Assertion failed) dims <= 2 && step[0] > 0 in function ‘cv::Mat::locateROI’

错误提示：
error Traceback (most recent call last)
in
17 fileName = ‘Po/z’+str(i+1)+’.jpg’
18 img = cv2.imread(fileName)
—> 19 hist = hog.compute(img,(8,8))
20 for j in range(0,featureNum):
21 featureArray[i,j] = hist[j]

error: OpenCV(3.4.2) C:\Miniconda3\conda-bld\opencv-suite_1534379934306\work\modules\core\src\matrix.cpp:755: error: (-215:Assertion failed) dims <= 2 && step[0] > 0 in function ‘cv::Mat::locateROI’

错误原因：图片的名称错误。

代码：

import cv2
import numpy as np
import matplotlib.pyplot as plt
PosNum = 820
NegNum = 1931
winSize = (64,128)
blockSize = (16,16)
blockStride = (8,8)
cellSize = (8,8)
nBin = 9
hog = cv2.HOGDescriptor(winSize,blockSize,blockStride,cellSize,nBin)
svm = cv2.ml.SVM_create()
featureNum = int(((128-16)/8+1)*((64-16)/8+1)*4*9)
featureArray = np.zeros(((PosNum+NegNum),featureNum),np.float32)
labelArray = np.zeros(((PosNum+NegNum),1),np.int32)
for i in range(0,PosNum):
    fileName = 'Po/z'+str(i+1)+'.jpg'
    img = cv2.imread(fileName)
    hist = hog.compute(img,(8,8))
    for j in range(0,featureNum):
         featureArray[i,j] = hist[j]
    labelArray[i,0] = 1
for i in range(0,NegNum):
    fileName = 'Ne/f'+str(i+1)+'.jpg'
    img = cv2.imread(fileName)
    hist = hog.compute(img,(8,8))
    for j in range(0,featureNum):
         featureArray[i+PosNum,j] = hist[j]
    labelArray[i+PosNum,0] = -1
svm.setType(cv2.ml.SVM_C_SVC)
svm.setKernel(cv2.ml.SVM_LINEAR)
svm.setC(0.01)
ret = svm.train(featureArray,cv2.ml.ROW_SAMPLE,labelArray)
alpha = np.zeros((1),np.float32)
rho = svm.getDecisionFunction(0,alpha)
print(rho)
print(alpha)
alphaArray = np.zeros((1,1),np.float32)
supportVArray = np.zeros((1,featureNum),np.float32)
resultArray = np.zeros((1,featureNum),np.float32)
alphaArray[0,0] = alpha
resultArray = -1*alphaArray*supportVArray
myDetect = np.zeros((3781),np.float32)
for i in range(0,3780):
    myDetect[i] = resultArray[0,i]
myDetect[3780] = rho[0]
myHog = cv2.HOGDescriptor()
myHog.setSVMDetector(myDetect)
imageSrc = cv2.imread('Test2.jpg',1)
objs = myHog.detectMultiScale(imageSrc,0,(8,8),(32,32),1.05,2)
x = int(objs[0][0][0])
y = int(objs[0][0][1])
w = int(objs[0][0][2])
h = int(objs[0][0][3])
cv2.rectangle(imageSrc,(x,y),(x+w,y+h),(255,0,0),2)
cv2.imshow('dst',imageSrc)
cv2.waitKey(0)

修改fileName,成功运行。