hi, On Tue, Jan 31, 2017 at 5:42 AM, Marcus Sundman <sund...@iki.fi> wrote: > On 30/01/17 10:13, johannes hanika wrote: > >> hi, >> >> i suppose you've seen this >> >> http://www.darktable.org/2016/05/colour-manipulation-with-the-colour-checker-lut-module/ >> ? > > > "to interact with the colour mapping, you can change both source and target > colours. the main use case is to change the target colours however, and > start with an appropriate palette" > > However, I want to do the opposite. I want to start with an appopriate > target palette (the xrite color checker card) and then pick the source > colors from the picture.
more specifically i meant the second half of it, about the darktable-chart tool. > By selecting different areas and shift-clicking the corresponding patches in > the palette I get to alter the image, but then there seems to be no way to > tell it what values those patches should have. I'd have to adjust the 4 > sliders, but that's impossible to get right. (At least in a reasonable > time.) I should be able to just choose the target colors from a drop-down, > or maybe be able to switch between the source palette and target palette. > (It's ok for me if the target palette is difficult to set up, that's > something I'd do only once, and the default one looks just like the xrite > color checker anyway, so maybe that would work as such.) > > And I specifically don't want to create any custom profile (I could have 5 > different lighting setups per photoshoot, so after 40 photoshoots I'd be > handling 200 profiles, which isn't manageable), I just want to use it to > apply the white balance. > >> i'd recommend using more than the 24 patches to create a really useful >> color lut. as opposed to white balance or an icc profile with a >> matrix, you'd get weird artifacts/overshoots from the interpolation of >> very sparse patches. in fact i'm thinking we should extend the >> profiling tool to support multiple it8 targets as input, with >> different exposures, to sample the gamut even better. >> >> other than that, sure, that'll potentially make your white balance more >> precise. > > Those 24 patches should still make for a more accurate white balance than > having only 1 patch, like the current white balance does, right? Even if I'd > be lazy and use only a subset of those 24 patches; say, 6 patches. not necessarily if you use the colour checker module. it does have a linear polynomial part in the interpolation, which may work well. the rest will fix individual colour points and leave the rest of the gamut to some smooth interpolation, for better or worse. it doesn't create a matrix fit that would show uniform behaviour over the full range of input colours. -jo ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
