Re: a naïve HDR experiment

[Jostein Øksne]

Ann,
You are certainly right about the washed-out areas. The white areas of
sky are burned out in the raw file, so there's nothing more to pull
out there.

I also agree with you that the tonemapped image looks generally too
bright. In the assembly, I think the software lift the shadows too
much. They actually end up brighter than they are in the +1
conversion. I'm not sure why this happens, but maybe the burned out
sky areas influence the calculations. I look forward to do a test with
multiple raw files to see if this behaviour change when the exposures
actually have details in the whole of the extended tone range.

What makes me like the tonemapped better than the curves-adjusted is
the rendering of the details in the foreground. With curves, the
deepest shadows look more blocked up than they do in the tonemapped
version.

Thanks for commenting, it's much appreciated.

Jostein

On 11/21/06, ann sanfedele <annsan at nyc.rr.com> wrote:
> Well now I have broadband so could look at this quickly -
> astherically, I certainly like the middle one the best..
> the silhouette of the tree against the deeper blue sky is the reason.
> THe sky in the last one is too washed out -
> dont know if this is helpful at all, though ;)
>
> ann
>
> Jostein Øksne wrote:
>
> > Gang,
> >
> > So far, I have understood that HDR images, or rather tone-mapped
> > images, could be a nice tool to render high-contrast scenes in a way
> > closer to what the brain perceives when looking at the scene, within
> > the capabilities of a computer screen. Or a printer output, for that
> > matter.
> >
> > There have been some outrageous examples of images produced with this
> > technique that looks truly outworldly, in the negative sense of the
> > word.
> >
> > So what's the fuss? Time to try. :-)
> >
> > I have no idea if this is the best tool for the job, but it's free:
> > http://www.fdrtools.com/fdrtools_basic_e.php
> >
> > And here's my test. I developed a raw file with the Pentax PhotoLab 3
> > with -1, straight, and +1 stops compensation, and then merged them
> > with the FDRtool. I also tried to develop the raw file two times, with
> > special attention to highlights and shadows, respectively. The
> > highlight priority was then treated to a layer of curves with
> > Photoshop to try to bring back some detail in the shadows.
> >
> > Here's my result. Dialup warning: file is 266 kB, and 1000 pixels wide.
> >
> > http://www.oksne.net/paw/hdrtest.html
> >
> > I have no idea if I've done it right, but I think it looks promising
> > as a technique to handle this kind of light situation. I'd very much
> > like to hear your thoughts too.
> >
> > The pic, btw, is taken in Oxfordshire one December evening last year,
> > on an evening stroll by the Thames with mr. Ptaak Cottrell. :-)
> >
> > Cheers,
> > Jostein
> >
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