Re: [Openexr-devel] Setting compression mode for write?

[Richard Annema]

Hi Charles,

>From the OpenEXR File Format details :
( http://www.openexr.net/details.html )

"Data Compression

OpenEXR currently offers three different data compression methods [rle, zip,
piz], with various speed versus compression ratio tradeoffs. All three
compression schemes are lossless; compressing and uncompressing does not
alter the pixel data. Optionally, the pixels can be stored in uncompressed
form. With fast filesystems, uncompressed files can be written and read
significantly faster than compressed files."

One thing you may run into, which isn't related to compression, is
first-generation loss from an original when you use a non-1.0 exponent upon
saving. This is to be expected, though.

Best regards,
Richard Annema

----- Original Message -----
From: "Charles Henrich" <address@hidden>
To: "Paul Schneider" <address@hidden>
Cc: <address@hidden>
Sent: Friday, April 18, 2003 21:15
Subject: Re: [Openexr-devel] Setting compression mode for write?


> All of the compression methods are lossless, yeah?
>
> -Crh
>
> > It's an optional argument to the Header constructor.  Check out this
portion
> > of the sample I sent you yesterday:
> >
> > Header header (w, h, 1, Imath::V2f (0, 0), 1,
> > Imf::INCREASING_Y, Imf::ZIP_COMPRESSION);
>
>        Charles Henrich                                   address@hidden
>
>                          http://www.sigbus.com/~henrich
>
>
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