Hi Zachary,

The difference between ZIP and ZIPS is that ZIPS compresses a single line
at a time whereas ZIP does it in chunks.

For reference, http://openexr.com/TechnicalIntroduction.pdf,  pp16


On 4 January 2017 at 15:16, Larry Gritz <[email protected]> wrote:

> In EXR speak, "zip" is the usual deflate/zip compression in blocks of 16
> scanlines, and "zips" is the same compression method, but applied to each
> scanline individually. Both are supported by OIIO.
>
> The compression/decompression is handled on the OpenEXR library side, not
> by the OIIO code itself, so in theory anything should be fine with either
> one. Though I do see a comment in my code indicating that only "zips" has
> been found to be reliable for deep files.
>
> Can you give more detail about what's going wrong? You're rendering out an
> exr with "zips"? Writing it with OIIO? Then it's "borken" when you
> "process" them... in what way is it broken, how processed, in what program
> does it appear broken? (Is that when also reading with OIIO, or some other
> app?)
>
> Which versions of OIIO and OpenEXR are you using?
>
> Can you either send me one of these broken files to inspect, or else give
> a recipe for how to create one (ideally using only OIIO components)?
>
>
> On Jan 4, 2017, at 2:28 PM, Zachary Bauer <[email protected]>
> wrote:
>
> Hello,
>   A question about OIIO compression support:
>
> I am having redshift output Multi-Part EXRs and their headers say their
> compression is "zips". Typically what I see is "zip" compression for my
> EXRs from other renderers (PRMAN). Processing these redshift images using
> Open Image IO is resulting in broken images, but if I convert them to "zip"
> compression using oiiotool first, everything seems to work ok.
>
> Is "zips" compression different than "zip"?
> Does OIIO support "zips"?
>
> Thanks,
> Zachary Bauer
> Senior Software Engineer (Tools)
> Blizzard Entertainment
>
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>
> --
> Larry Gritz
> [email protected]
>
>
>
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>
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