I do mine in 48-bit TIF, which is 16-bit per channel RGB. 48-bit color
is my DSLR's native depth.
Real HDR is done using multiple frames, shot at various exposure ranges
so the darkest exposure gives you no clipping at the dark end, and the
highest exposure gives you no clipping at the bright end, with enough
intermediate frames to give you good exposures through the midranges.
Enfusing with the full 48-bit color range gives you better results. When
Hugin finishes an image for image, it's a 48-bit color TIFF, not a
24-bit TIF.
I don't think enfuse reduces the dynamic range to 24-bit color.
On 11/19/2012 08:29 PM, TvE wrote:
Roger, I'm not sure things are as drastic as you make them when you say
"What is needed for HDR work, is either a floating point format
(about 12 bits per channel, would be sufficient, but 32 bits per channel
are normally used in hugin) or a high-bit-count fixed-point format."
Yes, to get the best possible results, you are correct. However, as far
as I can tell, when Carlos runs enfuse on a stack, enfuse compresses the
dynamic range into the available 24 RGB bits. So if the stack has a
large dynamic range, he's loosing some color subtlety and some sensor
noise, but he's not loosing highlights or shadows per-se. If he's then
putting everything together into one 24-bit RGB image at the end without
manual tone mapping, I'm not sure there is much quality to be gained by
going through 48-bit or 96-bit intermediate images. Maybe you or someone
has some examples where it does make a difference?
On Monday, November 19, 2012 3:06:02 AM UTC-8, rew wrote:
Guys,
when you say "24 bit jpeg" almost everybody thinks of this as "full
color (RGB), 8 bits per channel".
What is needed for HDR work, is either a floating point format (about
12 bits per channel, would be sufficient, but 32 bits per channel are
normally used in hugin) or a high-bit-count fixed-point
format. Something like 16 might get close, but 24 bits per channel.
may be more appropriate.
JPEG format is not appropriate for non-8-bit-per-channel-data. So
Carlos in the workflow that you describe you're truncating a lot of
information when you output your intermediate files into the 8-bit
jpeg format.
So... Carlos, I would suggest that you try saving your intermediate
files as tiff, and then find out what options you have to create a
32-bit-per-channel-floating-point intermediate file. Then Hugin can,
while stitching, apply proper exposure corrections and things like
that. (or are you fixing the exposure bracket for the whole panorama?
In that case Hugin's exposure correction should be unneccessary.)
Roger.
On Mon, Nov 19, 2012 at 08:35:41AM -0200, Carlos Eduardo G. Carvalho
(Cartola) wrote:
> Hi,
>
> just to clarify, I don't work with 24-bit jpg. I usually shoot in
JPG and
> work with it in 8 bits. But alit_image_stack can deal with tif
and you can
> work with tif all the time. I just put JPG in my example because
I use it :)
>
> I sometimes have some ghosts in the final result of the enfusion,
but I
> doubt if it would solve using a larger image. I think they happen
because
> of parallax differences. I can clearly see that part of the image
is good
> and another is not, so I think align_image_stack has done it's
job. The
> solution (maybe) would be distort the image before fuse them and
maybe
> hugin does that, I don't know. In fact I have never tried to make
the
> exposure stacks directly into hugin. Maybe I should also give it
a try :)
>
> And surely the best option of all is to stabilize the camera to
shoot, but
> sometimes it is a little hard to do:
>
http://cartola.org/fotos/_cache/Diversas/Engenhocas/_screen/20111004-mastro.jpg
<http://cartola.org/fotos/_cache/Diversas/Engenhocas/_screen/20111004-mastro.jpg>
>
> Cheers,
>
> Carlos E G Carvalho (Cartola)
> http://cartola.org/360
> http://www.panoforum.com.br/
>
>
>
> 2012/11/18 TvE <[email protected]>
>
> > Carlos, thanks for posting your steps. Running
align_image_stack from the
> > command line sounds like a nice idea. You could also output the
result into
> > the .pto file, I believe. I don't know about pre-fusing each
stack into a
> > 24-bit jpg. I would be concerned that you could end up with
images that
> > have very different dynamic ranges and that don't blend well
into the final
> > pano. E.g. if one stack has sunset-to-dark and the other is
all-dark. But
> > maybe enfuse deals with that properly or maybe those scenarios
don't fuse
> > well either way... If I have the time I may give the two
approaches a spin.
> > Another advantage of not pre-fusing is that align_image_stack
sometimes has
> > difficulties, specially when large areas are very dark or blown
out in one
> > of the images of the bracket and it's nice to be able to adjust
the control
> > points in hugin. Ah. maybe we can collect some more wisdom and
then turn
> > this thread into a wiki page.
> >
> > --
> > You received this message because you are subscribed to the
Google Groups
> > "Hugin and other free panoramic software" group.
> > A list of frequently asked questions is available at:
> > http://wiki.panotools.org/Hugin_FAQ
<http://wiki.panotools.org/Hugin_FAQ>
> > To post to this group, send email to [email protected]
> > To unsubscribe from this group, send email to
> > [email protected]
> > For more options, visit this group at
> > http://groups.google.com/group/hugin-ptx
<http://groups.google.com/group/hugin-ptx>
> >
>
> --
> You received this message because you are subscribed to the
Google Groups "Hugin and other free panoramic software" group.
> A list of frequently asked questions is available at:
http://wiki.panotools.org/Hugin_FAQ
<http://wiki.panotools.org/Hugin_FAQ>
> To post to this group, send email to [email protected]
> To unsubscribe from this group, send email to
[email protected]
> For more options, visit this group at
http://groups.google.com/group/hugin-ptx
<http://groups.google.com/group/hugin-ptx>
--
** [email protected] ** http://www.BitWizard.nl/ **
+31-15-2600998 **
** Delftechpark 26 2628 XH Delft, The Netherlands. KVK: 27239233
**
*-- BitWizard writes Linux device drivers for any device you may
have! --*
The plan was simple, like my brother-in-law Phil. But unlike
Phil, this plan just might work.
--
Gnome Nomad
[email protected]
wandering the landscape of god
http://www.clanjones.org/david/
http://dancing-treefrog.deviantart.com/
http://www.cafepress.com/otherend/
--
You received this message because you are subscribed to the Google Groups "Hugin and
other free panoramic software" group.
A list of frequently asked questions is available at:
http://wiki.panotools.org/Hugin_FAQ
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at http://groups.google.com/group/hugin-ptx
