With respect to the observation that "exposure change resulting from
changes in light levels as the sun hides behind a cloud", I also find this
occasionally.
For context: I shoot D300 RAW, convert RAW to 16 bit .tiff in ACR
(Photoshop Extended CS4), and pull the .tiff into PTGUI. All processing is
done on an oldish MacBook Pro. My overlaps are usually 25% or more, can go
as high as 50% under operator error.
Here's what I do to "correct" exposure differences when they propagate
through the PTGUI blender and compromise the resulting panorama:
1. Review image in PTGUI Panorama Editor in the "Preview without
Blending". This makes the tonal variations between overlapping images
visible, especially when they're large.
2. Working one source image at a time, identify images that exhibit large
tonal shifts. Keep the project open in PTGUI, and stand by for some PTGUI
magic: delete the offending .tiff, pull the source RAW into ACR, and adjust
exposure up or down as appropriate (this is a guessing game), and create a
fresh .tiff directly from ACR to replace the one you just deleted. Hurry
back to PTGUI, and you will see PTGUI refresh the panorama when the new
.tiff is available (magic!!!). Repeat as needed.
I delete offending .tiff files because ACR will use a different name for
the new .tiff if the old one is still around. My ACR does not overwrite
the pre-existing .tiff. If you prefer to keep the offending .tiff, you
have two options: a) move it out of the current directory, or b) go to the
"Source Files" tab in PTGUI and replace the old .tiff with the new one.
You guys probably know a thousand variations on this theme, hope you find
this useful.
Joost, does this PTGUI magic also work under Windows?
Regards
On Thursday, November 1, 2012 11:00:17 PM UTC-4, UtahBob wrote:
> On Thursday, November 1, 2012 8:05:42 AM UTC-4, PTGui Support wrote:
>> It looks like there is a linear brightness gradient from left to right
>> (as seen in portrait orientation). This should be due to a difference
>> between the opening and closing speed of the shutter. Does the fz200
>> have a physical curtain shutter?
>> This kind of exposure correction is currently not supported, but it's on
>> the wish list.
>> Joost
>> Joost,
> I'm seeing somewhat the same issue as well as exposure change resulting
> from changes in light levels as the sun hides behind a cloud. I'm at a
> loss as to why the blenders have issues blending out these brightness
> changes from frame to frame even with Enblend and Smartblend. Just for
> kicks I tried Enblend on Tom's pano section and the results were almost
> identical to the PTGui blender along with no appreciable difference when
> changing the Enblend "levels" option. It seems to me that the problem
> impacts smaller panos less such as sphericals which seems to blend well
> when using 6 shots around. I recall in the past that enblend did a great
> job hiding exposure differences from frame to frame especially when using
> the -a command and those where differences substantially in excess of what
> we are talking about here. I don't see that great blending anymore and I
> just don't understand what has changed?
> I guess I have a lot of panos that I have sitting fully unprocessed
> waiting for a better blender and perhaps I need to focus on preprocessing
> the individual images for consistent light levels within and among images.
> I'm thinking that's a difficult process for multigigapixel images and
> probably why I have not tackled it.
> Also, I've been wanting to confirm - do the blend seams shown in the Pano
> Editor carry over for use by Enblend and Smartblend? If not, does the
> masking somehow carry over and impact the Enblend and Smartblend processing?
> Thanks,
> Bob
