On 09/01/2010 10:08 AM, David Gowers wrote:
 > Sounds like a great idea!
Good. ;) And thank you for helping.

 >>           [ what about "luma", "chroma", "alpha"? ]
 > AFAICS those are misleading -- I think they are booleans
 > (ie 'this is a luma channel'* (L of LAB/LCH or Y of (graY)),
 > 'this is a chroma channel' (A/B of LAB; Cb/Cr of YCbCr),
 > 'this is an alpha channel' (.. alpha) )
 > [...]
 > * AFAICS, 'luma' is meant in a loose sense here.."this channel encodes
 > brightness in some sense" not "this channel encodes X specification of
 > brightness"

I also understand those as a hint to babl as to what kind of information 
the component encodes. But it rather seems to be reserved for future 
babl magic?

 >>      [ naive-CMYK e.g. registers "CMYK" but not "RGBA".
 > RGBA is the responsibility of model-rgb.c , IIRC.
 > I'm not sure what it was you meant to say here.

If you supply a conversion, you'll have to be sure the respective models 
exist in babl.

My assumption was that either you know they do, because they are part of 
'core babl' (like RGBA), or you should make sure by registering it yourself.

Relying on another extension to have registered the model doesn't seem
stable. (What if that other extension is not loaded first, or removed
altogether?). [ but see below ]

 > As far as I can see, you probably only want to:
 > [...]
 > 3. (no need to register new models or components)
I would have expected that I do have to register Lab/LCH models (of
course not creating conflicts by registering them differently) because
so far they are only registered by another extension. -- 'have to'
meaning 'in order to play nice' as it would probably work to just let
the other extension register them.

Unless of course I do not regard the new conversions as
separate/parallel to the existing, but rather an add-on to the existing
Lab conversions. -- I didn't see it that way yet.
In that case, it might also be right to add the new source to the
current lib. (I.e. in Makefile.am, only add the source to an existing
lib -- not create a new lib)


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