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UnrecognizedImageError - image insertion error - python-docx


I am trying to insert an wmf file to docx using python-docx which is producing the following traceback.

Traceback (most recent call last):
  File "C:/Users/ADMIN/PycharmProjects/ppt-to-word/ppt_reader.py", line 79, in <module>
    read_ppt(path, file)
  File "C:/Users/ADMIN/PycharmProjects/ppt-to-word/ppt_reader.py", line 73, in read_ppt
    write_docx(ppt_data, False)
  File "C:/Users/ADMIN/PycharmProjects/ppt-to-word/ppt_reader.py", line 31, in write_docx
    document.add_picture(slide_data.get('picture_location'), width=Inches(5.0))
  File "C:\Python34\lib\site-packages\docx\document.py", line 72, in add_picture
    return run.add_picture(image_path_or_stream, width, height)
  File "C:\Python34\lib\site-packages\docx\text\run.py", line 62, in add_picture
    inline = self.part.new_pic_inline(image_path_or_stream, width, height)
  File "C:\Python34\lib\site-packages\docx\parts\story.py", line 56, in new_pic_inline
    rId, image = self.get_or_add_image(image_descriptor)
  File "C:\Python34\lib\site-packages\docx\parts\story.py", line 29, in get_or_add_image
    image_part = self._package.get_or_add_image_part(image_descriptor)
  File "C:\Python34\lib\site-packages\docx\package.py", line 31, in get_or_add_image_part
    return self.image_parts.get_or_add_image_part(image_descriptor)
  File "C:\Python34\lib\site-packages\docx\package.py", line 74, in get_or_add_image_part
    image = Image.from_file(image_descriptor)
  File "C:\Python34\lib\site-packages\docx\image\image.py", line 55, in from_file
    return cls._from_stream(stream, blob, filename)
  File "C:\Python34\lib\site-packages\docx\image\image.py", line 176, in _from_stream
    image_header = _ImageHeaderFactory(stream)
  File "C:\Python34\lib\site-packages\docx\image\image.py", line 199, in _ImageHeaderFactory
    raise UnrecognizedImageError
docx.image.exceptions.UnrecognizedImageError

The image file is in .wmf format.

Any help or suggestion appreciated.


Solution

  • python-docx identifies the type of an image-file by "recognizing" its distinctive header. In this way it can distinguish JPEG from PNG, from TIFF, etc. This is much more reliable than mapping a filename extension and much more convenient than requiring the user to tell you the type. It's a pretty common approach.

    This error indicates python-docx is not finding a header it recognizes. Windows Metafile format (WMF) can be tricky this way, there's a lot of leeway in the proprietary spec and variation in file specimens in the field.

    To fix this, I recommend you read the file with something that does recognize it (I would start with Pillow) and have it "convert" it into the same or another format, hopefully correcting the header in the process.

    First I would try just reading it and saving it as WMF (or perhaps EMF if that's an option). This might be enough to do the trick. If you have to change to an intermediate format and then back, that could be lossy, but maybe better than nothing.

    ImageMagick might be another good choice to try because it probably has better coverage than Pillow does.