Cool, thanks!
Just to emphasize: there's nothing wrong with the DWA compression. It works
great -- wonderful compression ratio with good visual quality, and the
performance problems I noted are evident with plain old "zip" compression. (It
speeds up slightly with DWAA, in fact, because there's less to read from disk,
and gets faster the more aggressively you compress, but it still doesn't catch
up to TIFF in performance at any compression level.)
In fact, the DWA compression works so well, I really want to see if it's
practical for textures (if only I can fix the perf issues so it doesn't come at
the cost of time). I had never considered lossy compression for texture before,
but the immense amount of texture space and bandwidth we now face certainly
makes me curious about under what conditions you guys find it useful. I figured
you must have a particular use case to have done the work to create it.
I have been working on this on and off for the past couple weeks, so it's very
much at the top of my mind, and had been meaning to quetly contact DWA and also
Piotr or somebody else with intimate knowledge of the libIlmImf internals, but
I started my winter break before I got a chance to send those emails. So this
thread is just getting me ahead of schedule, and with the added bonus of being
in public! I think many brains may make quicker work out of this, and any
forthcoming fixes will benefit us all.
My preferred solution is to find some silly and easily fixable thing in
libIlmImf to make its performance be close enough to TIFF that we can switch
our uint16 TIFF textures to half OpenEXR, and then have the option of at least
trying out the DWA lossy compression. The backup plan is to see if it's
feasible to extract the DWA compression code from OpenEXR and fashion it into a
custom codec for libtiff. But that's a little icky because literally no
non-OIIO apps would be able to read the files (like is already the case for
half tiff, but even worse).
-- lg
> On Dec 23, 2015, at 12:38 PM, Bruce Tartaglia
> <[email protected]> wrote:
>
> Hi Larry,
>
> Thank you so much for such an informative email!
>
> As far as the DWA format goes, Eric Tabellion passed your
> comments along to the developer of the format.
>
> The developer has already started looking into this, and may reply as
> early as today, but more likely, after the winter break (starting in 2 hours).
>
> So more than anything, I wanted you to know that several of us
> are looking into what you've said, and hope to get back to you
> in detail as soon as we can.
>
> Thank you again!
>
> Bruce
>
>
--
Larry Gritz
[email protected]
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