Re: DRAFT: eXIF 2017-05-28

On 30 May 2017 at 01:29, Cosmin Truta wrote:
> Wanna crop an image (e.g. in the way in which pnmcut works)? Or
> rotate, or flip horizontally, vertically, etc.? Simple, right? Well,
> however simple that may be, forget about updating an unsafe-to-copy
> eXIF, for the sake of correctness, because you would have to (#1)
> decode the MakerNotes, (#2) recalculate the correct positions, (#3)
> re-encode the MakerNotes. Each of these three steps are difficult,
> step (#2) is HORRIBLY difficult, and I presume that no implementors
> will bother.

Oops it's late at night. The paragraph I wrote is not self-contained.
I forgot to mention that step (#2), the one I referred to as "HORRIBLY
difficult", is like that because recalculating the correct positions
of the focus points in the newly-cropped/rotated/flipped image (to
make the whole thing correct for the sake of unsafe-to-copy-ness) is
that horribly difficult. Never mind arbitrary rotations (which make it
that much harder), or lens distortion operations (which make the whole
thing absolutely impossible).

Sincerely,
Cosmin

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