Whither Krita?

[Matthew Woehlke]

Cyrille Berger wrote:
> On Tuesday 22 September 2009, Sven Langkamp wrote:
>> What would a 'color space change' mask be? Is there a case were it's needed
>> to convert the colorspace manually with a mask?
> Yes. Two cases actually, tone-mapping and raw. For raw, some of the algorithms 
> can be applied on a raw colorspace (well curves), some other would need to be 
> applied on a RGB one.

I thought we'd said we wouldn't have a "RAW" colorspace, just va16¹? You 
can't debayer as a mask² anyway, it's a specialized convolution filter.

(¹ 'v' = value = grayscale)
(² at least I think not; wouldn't a cs-conversion mask normally be 
necessarily 1:1?)

This is actually a good point, though, what is the use case for 
cs-convert as a mask? I would rather have it built into filters, such 
that you can specify how the filter should read its input (i.e. what 
color space, what channel(s)).

IOW, instead of filter takes cs of underlying layer and applies to all 
channels, you have this:

under layer -> cs conversion+selector -> filter -> cs conversion+mapping 
-> channel fill -> layer blending

The default of course is 'underlying cs, all channels' and 'underlying 
cs, normal mapping'. But you could have, for example:

   blending
   map to pb,pr channels, ypbpr
   gaussian blur
   ypbpr, pb,pr channels
rgb layer

...a.k.a. "chromatic noise reduction" :-).

IOW how it works is, you say what channel(s) you want to feed the 
filter. An implicit cs conversion is done to get these channels. The 
filter needn't know what they are, all it knows is how many channels it 
operates on. This gives you that many output channels, which you map 
onto whatever channels of whatever cs you want. If you have all channels 
in that cs, you can skip channel fill, else you convert the input to the 
output cs and use that to fill in whatever channels you are missing. 
Then you perform blending as normal.

Hmm... okay I thought of a reason for masks :-). You could use them to 
arrange for layer blending to be done in a certain color space.

I guess a better question is if you can set up a stack where you can 
leverage conversion masks to accomplish the above. Mostly channel 
selection is the problem, I think... also if the UI wouldn't be better 
parking the above stuff with the filter.

-- 
Matthew
Please do not quote my e-mail address unobfuscated in message bodies.
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End of Transmission