Sorry, maybe i wasn't making myself clear. By "simple" i meant : an invert
operation *without* the "color of film material" feature. Like the "invert"
operation in Gimp.
Here's a screenshot with Pascal's style applied:
http://emremeydan.com/tempor/screenshot.jpg
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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