Re: [SPAM] Re: [Openexr-user] Questions for more experienced users

[Kevin Wheatley]

Florian Kainz wrote:
> A mip-mapped OpenEXR file is 33% larger than a single-resolution file,
> and the data rate required for real-time recording increases 
> correspondingly.
> (Some file formats, for example JPEG2000, use a clever compression method
> that allows you to extract a lower or higher resolution image depending on
> how much of the file you read.  Such a multi-resolution file is no larger
> than an equivalent single-resolution file.  Explicitly storing the lower-
> resolution levels makes OpenEXR files larger, but the multi-resolution 
> capability becomdes independent of the compression method, and image
> writers have full control over the content of the lower-resolution images.
> The writer may have specific requirements for filtering, subsampling and
> treatment of edges.

Yes JPEG 2000's available sub resolutions are constructed using a 
fixed set of wavelet filters, even comparing them to the usual 
suspects for subsampling their ferequency response isn't ideal for our 
uses, plus the decoding isn't exactly fast!

Re Ben's telecine suggestion ... well thats a can of worms... IF you 
take a view of OpenEXR representing 'focal plane' colourimetry, then 
the scanner and telecine manufacturers are going to have to add some 
seriously 'out of domain' user tweakable functions, e.g. allowing for 
CTL transforms derived from the settings the grader/colourist used (it 
gets worse if you need to include lab effects), this would be real 
ugly to get operationally working across the different facilities and 
machines. much simpler to have them output something nearer the film 
density space and convert separately.

Kevin

--
| Kevin Wheatley, Cinesite (Europe) Ltd | Nobody thinks this      |
| Senior Technology                     | My employer for certain |
| And Network Systems Architect         | Not even myself         |