def convert_to_image_file_format(format_str):
  """Converts a legacy file format string to an ImageFileFormat enum value.

  Args:
    format_str: A string describing an image file format that was passed to
      one of the functions in ee.data that takes image file formats.

  Returns:
    A best guess at the corresponding ImageFileFormat enum name.
  """
  if format_str is None:
    return 'AUTO_JPEG_PNG'
  format_str = format_str.upper()
  if format_str == 'JPG':
    return 'JPEG'
  elif format_str == 'AUTO':
    return 'AUTO_JPEG_PNG'
  elif format_str == 'GEOTIFF':
    return 'GEO_TIFF'
  elif format_str == 'TFRECORD':
    return 'TF_RECORD_IMAGE'
  else:
    # It's probably "JPEG" or "PNG", but might be some other supported format.
    # Let the server validate it.
    return format_str