code: def parse(cls, fptr, offset, length):
          
          nbytes = length - 8
          data = fptr.read(nbytes)
          bpc = tuple(((x & 0x7f) + 1) for x in bytearray(data))
          signed = tuple(((x & 0x80) > 0) for x in bytearray(data))
  
          return cls(bpc, signed, length=length, offset=offset)
docs: Parse bits per component box.
  
          Parameters
          ----------
          fptr : file
              Open file object.
          offset : int
              Start position of box in bytes.
          length : int
              Length of the box in bytes.
  
          Returns
          -------
          BitsPerComponent
              Instance of the current bits per component box.