Possible HDR stitching bug + advice sought on exposure and noise
Karmadillo
First the HDR issue.
For this panorama, all renderings of this image (Panorama editor,
preview, HDR image and tonemapped) show horizontal bands from the
centre of the shot toward the right of the image. Stitched for LDR
TIFF images.
Images:
Tonemapped with PTGui
http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/SydneyBotanical-manualexposureadjustment.jpg
Tonemapped with Luminance
http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Tonemappedwithlines.jpg
Project File: [will post shortly]
Secondly the quality issue:
At Christmas I shot an LDR panorama of Christmas lights.
In the Panorama editor it looks excellent - well aligned, nice color,
nice contrast, exposures and vignetting seem perfect.
http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Previewpane.jpg
However when I preview or stitch the results are inferior as good e.g.
noise, a red/orange color cast in the sky, sky is the wrong exposure.
http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Liam-Ct-CPsnoisy.jpg
Despite 2 hours experimenting with different settings for exposure,
colour balance, response curve and so forth I can't recreate the
quality of the Panorama editor screen.
Advice sought please.
Project File: [will post shortly]
PTGui Support
> System: Windows7 64 bit.PTGui Pro 9.1.2
>
> First the HDR issue.
> For this panorama, all renderings of this image (Panorama editor,
> preview, HDR image and tonemapped) show horizontal bands from the
> centre of the shot toward the right of the image. Stitched for LDR
> TIFF images.
> Images:
> Tonemapped with PTGui
> http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/SydneyBotanical-manualexposureadjustment.jpg
> Tonemapped with Luminance
> http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Tonemappedwithlines.jpg
> Project File: [will post shortly]
The sky looks suspicious: I'm seeing hard edges while it should be
smooth. You first need to solve that, the banding issue is probably
related. See 6.4:
http://www.ptgui.com/support.html#6_4
> Secondly the quality issue:
> At Christmas I shot an LDR panorama of Christmas lights.
> In the Panorama editor it looks excellent - well aligned, nice color,
> nice contrast, exposures and vignetting seem perfect.
> http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Previewpane.jpg
>
> However when I preview or stitch the results are inferior as good e.g.
> noise, a red/orange color cast in the sky, sky is the wrong exposure.
> http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Liam-Ct-CPsnoisy.jpg
This is a color management issue: currently the previews in PTGui are
not color managed but the generated panorama is tagged with the correct
color profile. So actually the stitched panorama has the right colors
and the preview in PTGui is off.
If you prefer the look of the panorama editor, here's a trick: since
PTGui is not color managed it will display the previews using a standard
sRGB profile. You can assign this profile to the resulting panorama in
e.g. Photoshop: Edit - Assign Profile. But keep in mind that this
actually creates the 'wrong' colors.
Joost
Karmadillo
Here are the project files that I promised to post:
HDR - http://df.arcs.org.au/quickshare/590700bed85186a7/Sydney%20Botanical.pts
There is a typo in the third sentence of my previous post. It should
be "HDR stitched from LDR Tiffs"
LDR - http://df.arcs.org.au/quickshare/54a243c526d642cb/Liam-Ct-CPsA.pts
I have also posted a vertical stripe of the output panorama at higher
resolution. At full resolution, noise, minor banding an other
artefacts are even worse.
http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Liam-Ct-outputstrip.jpg
Note that the dark areas of trees are too bright in the output
panorama and so the noise is amplified. I want to keep these areas
dark like in the preview.
The LDR pano was stitched from TIFF images. These don't have a linear
luminance profile. They have the standard curve that Adobe camera raw
applies. However in PTGui, the response curve displayed (the default)
looks like the logarithmic curve to be used to make linear RAW data
into a human friendly luminance scale. Is it possible that the wrong
curve is being applied, which is causing excessive brightening of
shadows (high contrast)?
On Jan 9, 8:06 pm, PTGui Support <supp...@ptgui.com> wrote:
> On 9-1-2012 0:32, Karmadillo wrote:
>
> > System: Windows7 64 bit.PTGui Pro 9.1.2
>
> > First the HDR issue.
> > For this panorama, all renderings of this image (Panorama editor,
> > preview, HDR image and tonemapped) show horizontal bands from the
> > centre of the shot toward the right of the image. Stitched for LDR
> > TIFF images.
> > Images:
> > Tonemapped with PTGui
> > Tonemapped with Luminance
> >http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20proje...
>
> The sky looks suspicious: I'm seeing hard edges while it should be
> smooth. You first need to solve that, the banding issue is probably
> related. See 6.4:
>
> http://www.ptgui.com/support.html#6_4
>
> > Secondly the quality issue:
> > At Christmas I shot an LDR panorama of Christmas lights.
> > In the Panorama editor it looks excellent - well aligned, nice color,
> > nice contrast, exposures and vignetting seem perfect.
> > However when I preview or stitch the results are inferior as good e.g.
> > noise, a red/orange color cast in the sky, sky is the wrong exposure.
PTGui Support
> Thanks for the tips.
>
> Here are the project files that I promised to post:
> HDR - http://df.arcs.org.au/quickshare/590700bed85186a7/Sydney%20Botanical.pts
> There is a typo in the third sentence of my previous post. It should
> be "HDR stitched from LDR Tiffs"
It looks indeed like you shot the photos in automatic exposure mode.
Take a look at the Exposure column in the Image Parameters tab. This
should be a strictly repeating sequence, eg
1/40
1/80
1/160
1/40
1/80
1/160
etc. Also ISO is varying between shots. And you have a varying number of
brackets for each shot (some 2, some 3).
See 6.1, 6.4 and 6.6:
http://www.ptgui.com/support.html#6_4
> LDR - http://df.arcs.org.au/quickshare/54a243c526d642cb/Liam-Ct-CPsA.pts
> I have also posted a vertical stripe of the output panorama at higher
> resolution. At full resolution, noise, minor banding an other
> artefacts are even worse.
> http://i198.photobucket.com/albums/aa290/rich_the_stitch/Pano%20projects/Liam-Ct-outputstrip.jpg
>
> Note that the dark areas of trees are too bright in the output
> panorama and so the noise is amplified. I want to keep these areas
> dark like in the preview.
>
> The LDR pano was stitched from TIFF images. These don't have a linear
> luminance profile. They have the standard curve that Adobe camera raw
> applies. However in PTGui, the response curve displayed (the default)
> looks like the logarithmic curve to be used to make linear RAW data
> into a human friendly luminance scale. Is it possible that the wrong
> curve is being applied, which is causing excessive brightening of
> shadows (high contrast)?
As I said the display within PTGui is off, because it isn't color
managed. The color of the output should more or less match the color of
the input (unless you have used the exposure/brightness adjustment tools
in PTGui of course).
Joost
Erik Krause
> The color of the output should more or less match the color of
> the input (unless you have used the exposure/brightness adjustment tools
> in PTGui of course).
Sorry, this is true only if you use Exposure Fusion for output. For True
HDR all depends on the tonemap settings. Tonemapping boosts the shadows
and hence amplifies noise. And of course exposure correction might
lighten some images more than others which would cause amplified noise
even for LDR panoramas.
--
Erik Krause
http://www.erik-krause.de
Erik Krause
> Take a look at the Exposure column in the Image Parameters tab. This
> should be a strictly repeating sequence, eg
> etc. Also ISO is varying between shots. And you have a varying number of
> brackets for each shot (some 2, some 3).
If you still want to get a good panorama from this images you can try to
exposure fuse them before stitching. Use a tool like f.e. EnfuseGui to
reduce each bracketed stack to a single LDR image, then stitch those
images. This might or might not work out depending on image content but
it's worth a try.
Karmadillo
The camera was in manual mode when these images were shot, fixed zoom
and focal length. However when the camera is switched to live view
mode it magically changes to an ISO priority type mode where it varies
ISO while keeping the other settings. This wrecks HDR panos!
I will try enfusing the images or HDR merging before stitching, and
see what happens.
Because of the high dynamic range of the image, some of the brackets
shot were pure black but with lots of noise because the camera
automatically ramped up the ISO. These made the final image worse so I
removed them from the pano.
I have captured the full dynamic range of the scene with this set of
photos so in theory it is possible to make an HDR pano from them. I am
not giving up on this pano yet. I am also not going back to the
location I shot it any time soon.
On Jan 13, 4:59 pm, PTGui Support <supp...@ptgui.com> wrote:
> On 13-1-2012 6:14, Karmadillo wrote:
>
> > Thanks for the tips.
>
> > Here are the project files that I promised to post:
> > be "HDR stitched from LDR Tiffs"
>
> It looks indeed like you shot the photos in automatic exposure mode.
> Take a look at the Exposure column in the Image Parameters tab. This
> should be a strictly repeating sequence, eg
> 1/40
> 1/80
> 1/160
> 1/40
> 1/80
> 1/160
>
> etc. Also ISO is varying between shots. And you have a varying number of
> brackets for each shot (some 2, some 3).
>
> See 6.1, 6.4 and 6.6:http://www.ptgui.com/support.html#6_4
>
>
>
>
>
>
>
>
>
> > resolution. At full resolution, noise, minor banding an other
> > artefacts are even worse.
Karmadillo
mode, and if the difference in ISO is taken into consideration, the
exposure of the images could be identical (or very close).
Perhaps I can make a copy of the images and manipulate the EXIF data
so that the ISO, shutter speed, and aperture are equal across the
bracketed sets. If that is mathematically correct, PTgui may stitch
the photos successfully.
PTGui Support
the exposure time, aperture and ISO of the images. So it is calculating
the actual amount of light captured during the exposure; if PTGui says
the images are taken at different exposures, they truly are.
But you can override the EXIF data by entering custom values in the
Image Parameters tab, also see 6.5:
http://www.ptgui.com/support.html#6_5
Joost
Erik Krause
> However when the camera is switched to live view
> mode it magically changes to an ISO priority type mode where it varies
> ISO while keeping the other settings.
Which camera? If it is a Canon EOS set LiveView mode to exposure
simulation...
Karmadillo
I'm aware of the fix, however ever time the camera powers off it
resets LiveView mode to movie+stills undoing the previous settings.
Next suggestion: change the auto power off settings so this doesn't
happen. Answer: I shoot in very hot conditions and the camera sensor
temperature climbs fast. Auto power off is useful.
Karmadillo
The HDR panorama worked well when converted to HDR segments and then
stitched.
Here is the result:
http://www.360cities.net/image/sydney-royal-botanic-gardens-harbour-foreshore
No blending lines, no tearing in the middle, no vortices or seam at
the +-180degree boundary.
Photoshop provided the tomeapping using the EXR output of PTGui.
The night-time Christmas lights panorama.
Used Adobe Camera RAW to make Tif files and then stitched this using
the Tif files.
Will publish to this address: http://www.360cities.net/image/immersed-in-christmas-lights
At the time of posting this shows a low res version with some levels/
curves issues, however I will publish the finished one over the top
when I have edited out the vehicle number plates.
On Jan 13, 4:59 pm, PTGui Support <supp...@ptgui.com> wrote:
> On 13-1-2012 6:14, Karmadillo wrote:
>
> > Thanks for the tips.
>
> > Here are the project files that I promised to post:
> > be "HDR stitched from LDR Tiffs"
>
> It looks indeed like you shot the photos in automatic exposure mode.
> Take a look at the Exposure column in the Image Parameters tab. This
> should be a strictly repeating sequence, eg
> 1/40
> 1/80
> 1/160
> 1/40
> 1/80
> 1/160
>
> etc. Also ISO is varying between shots. And you have a varying number of
> brackets for each shot (some 2, some 3).
>
> See 6.1, 6.4 and 6.6:http://www.ptgui.com/support.html#6_4
>
>
>
>
>
>
>
>
>
> > resolution. At full resolution, noise, minor banding an other
> > artefacts are even worse.
Karmadillo
Photoshop.
On Feb 1, 11:00 am, Karmadillo <directrix.digi...@gmail.com> wrote:
> OK - here is the final outcome:
> The HDR panorama worked well when converted to HDR segments and then
> stitched.
Erik Krause
> I'm aware of the fix, however ever time the camera powers off it
> resets LiveView mode to movie+stills undoing the previous settings.
Really? My 5DII doesn't do that. If you have custom modes, use one of
them to store the settings. I have one for bracketed panoramas and one
for exposure controlled HD Video...
Joergen Geerds
Am 01.02.2012 01:47, schrieb Karmadillo:
> I'm aware of the fix, however ever time the camera powers off it
> resets LiveView mode to movie+stills undoing the previous settings.Really? My 5DII doesn't do that. If you have custom modes, use one of
them to store the settings. I have one for bracketed panoramas and one
for exposure controlled HD Video.
Karmadillo
It is occurring when I use the custom modes on the dial. C1 is
currently for HDR panos, C2 is for LDR panos, C3 is for using my home-
made tilt and shift lens.
Strangely it doesn't happen if I set the camera to manual mode and set
everything I need for panoramas. It remembers those when it powers off
and back on.
I am not yet on the latest firmware for the camera. Maybe it will be
better once I update that.
Ken Warner
I have a project that produces a final blended image that is slightly different than the detail viewer shows. That difference makes it hard to mask out stitching errors.
Here's a screen shot and a project file.
PTGui Support
For several reasons the blending in the detail viewer may not match the
blending in the actual panorama.
For example your panorama is blended as an equirectangular image while
the detail viewer is blended as a rectilinear image. Also the detail
viewer currently ignores the blend feather setting (it's planned to
support this in a future update though). And for proper blending the
detail viewer should take into account the image contents outside of the
detail viewer area, but it doesn't. Improving this would make the viewer
extremely slow since it would in fact need to stitch and blend the full
panorama in the background.
Joost
Ken Warner
PTGui Support
But indeed you could look at the panorama editor (maybe enlarge the
window), it should give a more realistic blending preview.
Joost