It doesn't work on blown clouds of course ... it turns the clouds blue, which is not exactly what one would want but if it is a bare sky that is blown it works fairly well.
David On 13-06-07 12:22 PM, johannes hanika wrote: > 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 >>> >>> The content of this email is private and confidential, and unless >> otherwise stated only the intended recipient may use the content of this >> email for its intended purpose. 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