RGB 16 bit as default when starting Krita

[Boudewijn Rempt]

On Thu, 21 Jan 2010, Cyrille Berger wrote:

> On Wednesday 20 January 2010, Martin Renold wrote:
> > > Third. You must use 16 bit or float for scRGB. Do you think degrading
> > > performance twice worth [...]
> > 
> > If you don't mind a non-Krita developer commenting: I would not be very
> > surprised if a high quality operation with all the proper rounding and
> > dithering in 8bpc is actually slower than doing the same in 16bpc with
> > straight forward math.  Of course much also depends on how carefully
> > optimized it is, and my guess might also be wrong.
> 
> It goes in the same direction as what pippin said on IRC:
> 18:47 < pippin> in my testing, 32bit float/component can actually be faster 
> than 8bit char/component
> 18:47 < pippin> since modern cpus actually have to struggle when operating on 
> chunks of 8bit memory...
> 18:47 < pippin> while they are designed to work on wider things
> 
> And of course usuage of memcpy balance in favor of 8bits. For the sake of the 
> discussion, it would be interesting to have real benchmarks on the subject.

I think that's part of what Lukas should be doing next week. Qt 4.6 now has 
a very nice benchmarking library, and we should use that to measure 

* read performance of the tiles system
* write performance of the tiles system
* performance of the iterators
* colorspaces

> > painting in linear light counter-intuitive.  I should add that I tried it
> > only for a few hours, and some people who also tried it (with other
> > programs) strongly disagree with me.  I did not take enough time to get
> >  used to it first, maybe I would have liked it in the end (or not).
> 
> I will write a longer explanation/answer on the two color spaces, but out of 
> curiosity, did you do artwork with real-life painting before ? Or did you 
> started with digital ? If you did started with digital, it would explain a 
> bias toward sRGB painting.
> 
> -- 
> Cyrille Berger
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