>
>
> because the white point/film material color is too dark. try manually
> adjusting the value in hsl to maybe like double what's in there
> (switch off color picking before).
>
>
Thanks, i will try that.
> after that i'd use the levels module to adjust black and white points.
>
> please think about this for a minute.. invert is (1-x) where 1 is how
> much light the film would transmit where no photons hit it. there's no
> simple or neutral solution what this 1 should be.. if you set it to
> (1,1,1) and assume it's white, you'll get random garbage.
>
>
Up until a few months ago, i used to export a lightly-processed (and still
negative) 16bit tiff from Darktable, and do the positive inversion and
curves adjustments in Cinepaint. It used to work well. But since i switched
to a newer version of Ubuntu, i can't get Cinepaint to install/compile/run
anymore. That was the reason i looked for a similar invert process in
Darktable. I understand that the operation methods of the two programs are
very different, so i guess i shouldn't expect a similar invert operation.
...
emre
> >
> > As you see, there's an abrupt tonal change in shadow areas, more obvious
> on
> > the edges. And the histogram also shows that the shadows are highly
> clipped.
> > If you look at the CR2 file i provided in the previous post, the original
> > negative has much smoother tonal transitions than that.
> >
> > And i had suspected that reversing the tone-curve wasn't maybe the right
> > thing to do. But still, the results i get with the reversed-tone-curve is
> > much better than what i get with the invert plugin.
> >
> > I know that there probably aren't many people using the invert plugin (at
> > least not the way i'd do), so it's not worth of your time trying to
> improve
> > it. I had just thought that it could perhaps be simple to add a button to
> > disable the color-subtraction feature.
> >
> > Is there a linear way of inverting the image within Darktable? I guess
> "base
> > curve" too wouldn't be linear?
> >
> > ...
> > emre
> >
> >
> >
> >
> >
> >
> >
> > On Fri, Jan 25, 2013 at 9:15 PM, johannes hanika <[email protected]>
> wrote:
> >>
> >> On Sat, Jan 26, 2013 at 7:42 AM, Emre Meydan <[email protected]>
> wrote:
> >> > Thanks, and thanks for the style, but i had also tried that. The
> problem
> >> > isn't that i can't get a neutral-ish image--i can. The problem is i
> end
> >> > up
> >> > with an image with increased contrast, that has lost subtle detail,
> that
> >> > looks like some curve is applied to it.
> >>
> >> the tone curve works in non-linear lab.
> >>
> >> > With your style, don't you see that the image has lost shadow detail
> >> > because
> >> > of clipped shadows? Try it once by disabling "invert" and applying a
> >> > reversed tone-curve ( \ ), you'll see the image is actually much
> >> > richer/subtler in tones compared to what invert does.
> >> >
> >> > What i'd really prefer is an "unedited" positive
> >>
> >> which is pretty much what pascal did. reversing the tone curve will
> >> not invert radiance.
> >>
> >> > that i can work on. That's
> >> > why i suggested to add an option for simpler inversion.
> >>
> >> life isn't simple, and no idea what you mean.
> >>
> >> -jo
> >>
> >> >
> >> >
> >> >
> >> > On Fri, Jan 25, 2013 at 7:24 PM, Pascal de Bruijn <
> [email protected]>
> >> > wrote:
> >> >>
> >> >> On Fri, Jan 25, 2013 at 7:14 PM, Emre Meydan <[email protected]>
> >> >> wrote:
> >> >> > Thanks Pascal, but i had already tried that. Even though the image
> >> >> > has
> >> >> > pure
> >> >> > (clipped) white in it, what the invert plugin results in is a badly
> >> >> > clipped
> >> >> > purple image. That's why i said the plugin was showing weird
> >> >> > behaviour.
> >> >> > I've
> >> >> > also tried selecting the actual film color and also black and a
> >> >> > mid-grey,
> >> >> > nothing seems to get me usable results. I think there is a bug with
> >> >> > the
> >> >> > plugin. Or does it malfunction only on my computer (because of a
> >> >> > library
> >> >> > issue maybe)?
> >> >> >
> >> >> > Here's a RAW file of a negative "scan", you can try it yourself:
> >> >> > http://emremeydan.com/tempor/IMG_2649.CR2
> >> >>
> >> >> Erhm, the film isn't neutral to begin with. So a pure white
> inversion,
> >> >> on a non-neutral image, will not give you a non-neutral result.
> >> >>
> >> >> If you use the colorpicker in the area between the negatives
> >> >> (resulting in green being subtracted) works fairly well (resulting in
> >> >> a reasonably neutral image). This is basically how the plugin is
> >> >> supposed to be used in the first place.
> >> >>
> >> >> And if you want a perfectly neutral end-result you'd need to keep the
> >> >> monochome plugin enabled at all times anyway.
> >> >>
> >> >> I've attached a style which worked well for me to illustrate.
> >> >>
> >> >> Regards,
> >> >> Pascal de Bruijn
> >> >
> >> >
> >> >
> >> >
> >> >
> ------------------------------------------------------------------------------
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> current
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> >> > MVPs and experts. ON SALE this month only -- learn more at:
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> >> > _______________________________________________
> >> > darktable-devel mailing list
> >> > [email protected]
> >> > https://lists.sourceforge.net/lists/listinfo/darktable-devel
> >> >
> >
> >
>
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