Re: Is Vuescan's "Neutral" color balance at fault?

"Bart van der Wolf" <bvdwolf@no.spam> wrote in message news:...
SNIP
> change the Crop|Preview area to Current

Intended to type "Crop Box" instead of Current.

Bart

Ok, so neutral is somewhat akin to PS autocontrast, and manual with
1/1/1 to PS autolevels? Ed explained this before, I wasn't paying
enough attention.

Still, I wonder why Vuescan white balance is having such pink cast.
The example I posted at the photo.net link, above, is tugboats on
bright early afternoon, light cloud cover. The film is Provia100.

As I said above, the only way I seem to be able to get white clouds
and such is by outputting none for color balance in Vuescan, then
doing autolevels with very light clip, in PS. Not so good?

Hmm, now Vuescan color balance manual with:

red: 1.00
green: .98
blue: .98

(increasing green and blue very slightly)

seems pretty well spot-on, for me with Scan Dual II and Provia100.
Virtually the same as ps autolevels workflow.

Close-up review of the two together in Photoshop CS:

The histograms very close, the apparent color balance also very close.

Tried right-clicking on a variety of white cloud mass to arrive at the
above adjustment.

STILL, what's with Vuescan white balance?

"Mendel Leisk" <leisk@telus.net> wrote in message
news:e59b7450.0405141833.4939add@posting.google.com...
SNIP
> The histograms very close, the apparent color balance also very close.
>
> Tried right-clicking on a variety of white cloud mass to arrive at the
> above adjustment.
>
> STILL, what's with Vuescan white balance?

Like any automatic procedure, or heuristic, it can fail under a set of
unfavorable conditions. On average it's quite good, sometimes it fails.
Since you cannot change its behavior, there's not much you can do. What you
*can* do, is make sure you scan slides as "Image", and try to get the film
base color right. Cropping the image slightly to incluse or exclude
a-typical areas (such as edges or strong colors) can also help the automatic
balancing. A subsequent right mouse button click on a neutral (non-clipped)
part of the image will get you closer. If you then lock image color, you can
tweak the result to your heart's delight.

Bart