I just added a 3rd method: using the Nik Color FX "Pro contrast" filter which reduces the cast and punches the contrast back up as well. Definitely did the best job. I set Reduce cast to 100%, Contrast to 10%, and Dynamic contrast to 20%.
The Nik plugins are free, and can be used from Lightroom and Photoshop (including Elements). On Sun, Mar 5, 2017 at 10:49 AM, Bruce Walker <[email protected]> wrote: > Alan, I suspect that your negatives have aged and the colour cast > you're seeing is also inconsistent across the image. > > Just for grins I downloaded that image and tried two correction > methods in Photoshop. > > One technique is really simple and quick but is meant for more subtle > casts and seems to subdue the midtone contrast in your image. It > involves compositing an image with a solid colour created with the > Average filter then inverting it, and blended using the Color blending > mode at a low opacity. 25% opacity looked about right to me. > > http://www.candidcass.com/quickly-easily-correct-color-casts-using-photoshop/ > > The other technique involves separately adjusting the RGB curves to > reduce the cast. It's much more subjective and hit-or-miss, depending > on your ability to eyeball the cast and also to know some colour > theory (which I'm weak on). > > You can see three images here: original, negative-average, and RGB curves. > > https://www.dropbox.com/sh/3n1cel5jz3fxw96/AAC2Ju1FNDxE-wOm-1qGloXqa?dl=0 > > The negative average de-cast looks the most accurate to me but seems > to subdue the colours. > > The RGB curves probably need more tweaking because now I think there's > a magenta cast, but the colour seems more vibrant. > > > On Sun, Mar 5, 2017 at 8:59 AM, Alan C <[email protected]> wrote: >> I picked up a slide copying attachment for my old M42 bellows with a view to >> copying all my slides & negatives. I know you guys all use Epson scanners >> but they are very expensive here. I set it up with a Super Tak 55/2 which >> gives about 90% coverage. 65mm is needed to get 100%. (Unfortunately I >> cannot use my K-mount lenses unless I replace the M42 flange with a K-mount >> one). Anyway, it works fine and as I would probably crop most of them, 90% >> is OK. Colour rendition & sharpness are good. Slides, no problem. However, I >> am getting yellow colour casts on the sky with negatives after inversion. >> Using an 80B filter on the lens or using the filters in Elements gives more >> or less the same result. Shooting RAW or JPEG makes little difference but >> shooting RAW allows me to batch process very easily. I used the sky for >> illumination. I can easily process 50/hour. Example: >> >> https://www.flickr.com/photos/wisselstroom/33222112546/ >> >> Any ideas on getting rid of the colour cast? >> >> Alan C >> >> --- >> This email has been checked for viruses by Avast antivirus software. >> https://www.avast.com/antivirus >> >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> follow the directions. > > > > -- > -bmw -- -bmw -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
