[Openexr-devel] 8 bit int?

[Larry Gritz]

I know this has been covered a couple time over the years, but from my 
cursory search of the archives, not lately, and not to my full 
satisfaction. :-)

Is anybody entertaining the idea of adding a uint8 data type to OpenEXR? 
 Sometimes (actually quite frequently) we store things in textures that 
do not need fp16 precision.

Objections I've seen in previous discussion:

"It's bad to store luminance" -> We store textures of things like masks 
or linear parameter values that are not luminance and 256 levels are 
more than enough.

"Use TIFF or PNG" -> But it's so much nicer to have all our textures in 
one format, and there is anecdotal evidence (which I'm trying to 
confirm) that libIlmImf is just flat-out faster to read texture than 
libtiff (though that's hard to verify with few useful data formats in 
common between TIFF and OpenEXR).

"Use fp16 with piz, it compresses as well as 8 bit" -> on disk, maybe, 
but it takes up twice the space in an in-memory tile cache.

I know you want to avoid a proliferation of data types.  I'm just 
talking about adding the one type that is by far the most common for 
source images.

Anything changed in your philosophy about this since the last time it 
came up?

--
Larry Gritz
address@hidden