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Subject: RE: [Tiff] BigTIFF Tag Value Count issue
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Thread-Topic: [Tiff] BigTIFF Tag Value Count issue
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From: "Loygorri, Fernando" <FLoygorr@inovant.com>
To: "Bob Friesenhahn" <bfriesen@simple.dallas.tx.us>
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> Some possible implementation languages do not even support unsigned=20
> types.

That's what I meant: Java is one of them.

> Is there an alternative to using unsigned 64-bit values to access=20
> large data?

There is a standard class, BigInteger, that is of arbitrary size.
Unfortunately, using objects like BigInteger instead of primitives
like long is slower and clumsier.

By using unsigned 64-bit values in BigTIFF instead of unsigned 32-bit
values in TIFF, we increase the range by a factor of 2^32.

By using signed 64-bit values in BigTIFF, which are equivalent to
unsigned 63-bit values, the range would increase by a factor of 2^31,
still a very respectable value.

Just to clarify, I'm not proposing that negative 64-bit values should
have any meaning. They should be outlawed by the spec. I'm proposing
that the spec outlaw values with the most-significant bit set, and
this only to accommodate languages like Java that have a 64-bit signed
type but no 64-bit unsigned type.

Regards,

FGL
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