Re: [Openexr-devel] RAW images in OpenEXR?

[Florian Kainz]

Alexander Forsythe wrote:
> Florian, 
> B44 and B44A are wonderful algorithms for traditional uses of OpenEXR, 
> but you correctly pointed out that Lossy compression methods (B44, B44A) 
> would introduce crosstalk between the channels.  This is 
> highly undesirable and exactly what the Red camera folks are now taking 
> a lot of heat for.  I'd suggest limiting compression to lossless 
> compression methods for RAW data storage. 

Hi Alex,

the proposed RAW storage format eliminates crosstalk between channels.
The channels are compressed individually, and no information leaks from
one channel into another.

Artifacts caused by lossy compression still introduce color and
luminance noise, just as with RGB or luminance/chroma images.  Sharpening 
peformed during conversion to RGB may amplifiy noise in luminance/chroma
images.  So far we haven't done any tests to determine which compression
methods would work well for RAW images.

Florian