code: def extract_jpeg_thumbnail(self):
          
          thumb_offset = self.tags.get('Thumbnail JPEGInterchangeFormat')
          if thumb_offset:
              self.file.seek(self.offset + thumb_offset.values[0])
              size = self.tags['Thumbnail JPEGInterchangeFormatLength'].values[0]
              self.tags['JPEGThumbnail'] = self.file.read(size)
  
          # Sometimes in a TIFF file, a JPEG thumbnail is hidden in the MakerNote
          # since it's not allowed in a uncompressed TIFF IFD
          if 'JPEGThumbnail' not in self.tags:
              thumb_offset = self.tags.get('MakerNote JPEGThumbnail')
              if thumb_offset:
                  self.file.seek(self.offset + thumb_offset.values[0])
                  self.tags['JPEGThumbnail'] = self.file.read(thumb_offset.field_length)
docs: Extract JPEG thumbnail.
  
          (Thankfully the JPEG data is stored as a unit.)