The optional header reader that makes §96's decoded-size limits pre-checks.
Returns the dimensions the encoded bytes claim, or undefined when this
probe does not recognise the format — which is treated as "unknown", not as
"fine", so the post-decode check still runs.
The optional header reader that makes §96's decoded-size limits pre-checks.
Returns the dimensions the encoded bytes claim, or
undefinedwhen this probe does not recognise the format — which is treated as "unknown", not as "fine", so the post-decode check still runs.