问python“可能不是pdf2image文件”错误

EN

from pdf2image import convert_from_path
import sys

images = convert_from_path("test.pdf",500)
for i in range(len(images)):
    images[i].save('page'+ str(i) +'.jpg', 'JPEG')

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/pdf2image/pdf2image.py", line 479, in pdfinfo_from_path
    raise ValueError
ValueError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "pdf_conv.py", line 7, in <module>
    images = convert_from_path(pdf_path,500)
  File "/usr/local/lib/python3.6/site-packages/pdf2image/pdf2image.py", line 98, in convert_from_path
    page_count = pdfinfo_from_path(pdf_path, userpw, poppler_path=poppler_path)["Pages"]
  File "/usr/local/lib/python3.6/site-packages/pdf2image/pdf2image.py", line 489, in pdfinfo_from_path
    "Unable to get page count.\n%s" % err.decode("utf8", "ignore")
pdf2image.exceptions.PDFPageCountError: Unable to get page count.
Syntax Warning: May not be a PDF file (continuing anyway)
Syntax Error: Couldn't find trailer dictionary
Syntax Error: Couldn't find trailer dictionary
Syntax Error: Couldn't read xref table