def _normalise_format(path, format, header=None):
"""Extracts ``"JPEG"``, ``"PNG"`` etc from arguments provided to image
read write methods. Implements the hierarchy for multiple arguments given.
- User explicitly gives format.
- Format read from header.
- Format read from filename suffix.
"""
if format is None:
if header is not None:
format = format_from_header(header)
if format is None:
try:
format = Path(path).suffix
except TypeError:
raise ValueError(
"No `format` argument was given and couldn't guess the format from `path`."
)
format = format.upper()
if format[0] == ".":
format = format[1:]
if format == "JPG":
format = "JPEG"
if format == "TIF":
format = "TIFF"
return format
