wow, that is a surprisingly cool trick, works really well. thanks for the
hint (i'm still going to fix the highlights module..).
-jo
On Sat, Jun 8, 2013 at 4:06 AM, David Vincent-Jones <davi...@frontier.com>wrote:
> I am noticing that with some blown sky situations if I use a parametric
> mask on the magenta area and then use the channel mixer to drop the red
> value to that of the green value, some level of the blue sky can often
> be recovered.
>
> David
>
> On 13-06-07 08:22 AM, Rob Z. Smith wrote:
> > OK, let me substitute 'not quite white' instead of grey.
> >
> > Imagine what is probably the most frequent use case of blown out areas
> in clouds. Rather than losing all detail my thoughts are that it might be
> best to do something like map (255,255,255) to white but say (255,254,243)
> to some averaged value such as (254,254,254). That would avoid colour
> casts but still avoid throwing away such highlight detail as remains in the
> unblown channels. I think it would look better than a large expanse of
> pure white.
> >
> > But retaining colour information would be better provided it doesn't
> cause colour casts. Raw Therapee have put a lot of work into this but even
> there you still you get colour casts, sometimes. Whenever we invent data
> with some interpolation algorithm there is always going to be the odd
> example that throws it.
> >
> > I haven't worked on a blown colour casted highlight reconstruction
> recently, but it strikes me that we can perhaps deal with such colour casts
> more easily in dt than any of the other raw converters. Let's say our
> reconstruction causes a typical magenta colour cast in the reconstructed
> areas around totally blown highlights - I suspect we could just use our
> parametric masks to run a magenta subtracting colour change just on the
> brightest pixels and if necessary add a drawn mask as well.
> >
> > -----Original Message-----
> > From: Chris Siebenmann [mailto:c...@cs.toronto.edu]
> > Sent: 07 June 2013 15:13
> > To: Rob Z. Smith
> > Cc: darktable-users; c...@cs.toronto.edu
> > Subject: Re: [Darktable-users] Best way to recover highlights that are
> blown in processing?
> >
> > | On 13-06-06 10:14 AM, Chris Siebenmann wrote:
> > | > I would be happy to see a highlights reconstruction option for 'if
> > | > any channel is clipped, set the pixel to white'. I might even
> turn
> > | > it on all the time.
> > [...]
> > |
> > | It might be nicer if such an option set the pixel to grey rather than
> > | white using the values of the remaining unblown channels to take a
> > | best guess at how near to full white that grey should be.
> >
> > My thinking on this is that white splotches on pictures look less ugly
> than grey splotches. To some extent we are trained (especially now) to
> expect very bright areas in pictures to be white; I'm not sure that very
> bright areas looking grey instead will look at all pleasent. I wouldn't be
> surprised if they came out looking rather wrong.
> >
> > - cks
> >
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