Re: [Openexr-devel] does half round-trip?

[Paul Miller]

Ken McGaugh wrote:
> I wrote a small program a while back to test this and it did
> round-trip without any loss.  For every 10-bit code value there
> was exactly one 16-bit half.  But in shake you have the extra
> step of going through 32-bit float which may introduce some
> rounding errors.

Are you encoding 0->1023 in half as 0->1023, or 0->1 (with super 
black/white)?



> Paul Miller wrote:
>
> > I'm working on an updated Cineon I/O module, and when I use 16 bit 
> > int, with the Cineon log data stretched to 0-65535, I can round-trip 
> > exactly.
> >
> > However, when I use half as an intermediate format with the cineon 
> > linearized between 0->1 (keeping super blacks and super whites), it 
> > does not seem to be round-tripping. It's close, and not noticable 
> > visually, but Shake's Common node is showing tons of "noise".
> >
> > Is this expected?


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Paul Miller | address@hidden | www.fxtech.com | Got Tivo?