Archived posting to the Leica Users Group, 2015/02/11
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I found a way to do better. < https://www.flickr.com/photos/24844563 at N04/15876024034/in/photostream/lightbox/ > I had bracketed my exposures. The original image I posted indeed had the core of the red tail lights blown. So was part of the moon. BUT... I had another image taken a couple of minutes later at about 2.5 stops less exposure. Here, a typical tail light ranged from about RBG = 255,160,80, to 192,79,61. But even so, the red tail lights still came up as white when I "developed" the image to a JPG with a width of 1200 pixels in Capture One. But when I exported that same image to a 16-bit TIF, and then downsized it in Picture Window Pro, things got much better. Sidways-viewed tail lights on the freeway were red. Tail lights pointing at the camera on the entrance ramp were orangy-pinkish, so they looked OK. And the moon is better in this picture. This is more like it, it looks like what I remember seeing. The RAW development algorithm and the resizing algorithm are both "black boxes." By using a different program to resize the image, I found a better black box for this situation. What does a program actually do when it has to mash four pixels down to one? Capture One (algorithm unknown) seems to emphasize the brightest pixel in the bunch. Picture Window Pro defaults to a Bicubic algorithm, which seems to weigh the darker pixels more, and I end up with something that looks like a bright tail light instead of a white pinpoint. Me happy. --Peter On Tue, Feb 10, 2015 at 12:09 PM, Mark Rabiner <mark at rabinergroup.com> wrote: > Hopefully its not in the firmware somewhere to get red of red eye. > > > On 2/10/15 5:19 AM, "Peter Klein" <boulanger.croissant at gmail.com> wrote: > > > We were treated to quite a show during our anniversary dinner. > > <https://www.flickr.com/photos/24844563 at 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 > > > > _______________________________________________ > > Leica Users Group. > > See http://leica-users.org/mailman/listinfo/lug for more information > > > > > -- > Mark William Rabiner > Photographer > http://gallery.leica-users.org/v/lugalrabs/ > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >