Sorry, I meant to say the I loved the moonrise and wouldn't have noticed
a few blown taillights.
Chuck Norcutt
On 2/10/2015 12:33 PM, Chuck Norcutt wrote:
IMHO, you're definitely up against over exposure regardless of what you
think is or isn't happening. You say "...underexposed drastically,
where all the RGB values are under 255." But I ask, determined how?
From the histogram? If you have a relative handful of blown red pixels
in a histogram representing 16 million pixels how significant is that to
the display of the graph? I submit they are there but unseen at the
level of detail displayed by the histogram.
You also say: "In shots with any decent city detail, the red channel
does hit 255, but the green and blue are much lower. Lowering the
exposure in post, or using highlight recovery has no effect." You are
hoping to see red but at 255 the red channel is already blown... 255
whether R, G or B channels is white. You should expect a light colored
blue-green pixel. The red part is already forever gone.
Probably the only way to get what you'd like (given the high dynamic
range of the scene) is an HDR image. But you're not going to get that
on the taillights of swiftly moving traffic... but you might be
successful with the static parts of the image whether red or some other
color. If it bugs you enough to do the work you could spot edit the
offending lights by pasting in some red from another car that didn't
show the problem.
I'm not familiar with Capture 1 (despite owning a very early copy) but
if you think ACR might possibly do a better job send me a raw file and
I'll give it a try. You might also try Oly Viewer 3 but I'm not
inclined to go there myself.
Chuck Norcutt
On 2/10/2015 5:22 AM, Peter Klein wrote:
We were treated to quite a show during our anniversary dinner.
<https://www.flickr.com/photos/24844563@N04/16304267069/>
I'd like some advice on a technical problem with this picture, and in
fact with all of the pictures I took of the city from atop the Needle.
Red car tail lights turn white. It isn't overexposure, because it
happens even on shots that I deliberately underexposed drastically,
where all the RGB values are under 255. In shots with any decent city
detail, the red channel does hit 255, but the green and blue are much
lower. Lowering the exposure in post, or using highlight recovery has
no effect.
This doesn't happen with larger areas of red light where the pixels have
the same values as the little tail lights. But taill lights turn white,
as do other points of colored light like the blue and green Seahawks
colors that still adorn some construction cranes. The key seems to be
that the light sources are just a few pixels in diameter.
Maddeningly, on the onscreen preview, the tail lights appear red. But
when I "develop" the JPG, they turn white.They also turn white if I blow
up the onscreen preview to 50% size or larger.
The camera is an Olympus E-M5 with 45/1.8 lens, and the RAW developer is
Capture One v. 7.1.2. Here's a screen clip of the whole picture,
followed by a section with and a string of car rears blown up to 400% so
you can see what's going on with the pixels.
<http://gallery.leica-users.org/v/pklein/temp/SpaceNeedleMoonriseScrPreview.JPG.html>
<http://gallery.leica-users.org/v/pklein/temp/SpaceNeedleMoonriseCars400pct.JPG.html>
Advice, anyone? Is this just an inevitable result of the Bayer array, or
is there a way to fix it?
--Peter
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|
