Tech Support > Computer Hardware > Scanners > Vuescan Buffer Percentage and Black Point
Vuescan Buffer Percentage and Black Point
Posted by Alan Smithee on July 18th, 2005


Why is it that when scanning Black and White negatives Crop | "Buffer
Percentage" seems to do more to affect the outcome of my black point than
adjusting the RGB Exposure? When I lock my RGB exposure at 1.0 why does the
program still respond to the "Crop | Buffer %" option? Shouldn't it cease to
work especially since I'm in a B&W mode?


Posted by Mendel Leisk on July 18th, 2005


Buffer ignores a strip around the edge of the image, the width of that
strip determined by what you type into buffer %. If there is an extra
bright or dark area in this zone, it will be clipped. It's typically to
ignore the film holder or edge of slide, but it usually enchroaches
into the image as well.

Posted by Alan Smithee on July 18th, 2005


Mendel Leisk wrote:
Yes it's suppose to ignore a certain area IF I'm letting Vuescan calculate
exposure (sic from the docs "Color balance" for colour films), remember I'm
scanning B&W not colour. But if I'm locking down my RGB exposure I don't
want the program to adjust the exposure which is what it "appears" to be
doing. In my case I have to adjust this setting to near 0% or zero% (the
default is 20%) or Vuescan clips the dark areas of my negative, (or, more
accurately, just cuts the shadows to close for my liking).



Posted by Mendel Leisk on July 19th, 2005


Sorry, overlooked that you're using locked exposure. Don't know then.

Posted by Erik Krause on July 19th, 2005


Alan Smithee <AlanSmithee@nowhere.com> wrote:

RGB exposure is the exposure of the CCD sensor. This is a pure hardware
setting and if you have locked it, it will not be changed.

However, if you do not lock image color (or set white balance to
'None') then black and white point are determined from the area which
is affected by the buffer setting (which is part of the post processing
vuescan does). Simply lock image color if you don't want this
behaviour.

I'm not sure whether you should lock RGB exposure to 1.0 since this
might be much too low to look through the densest parts of your neg's.
A better idea is to determine a value using 'advanced workflow' (see
manual)...

--
Erik Krause
Digital contrast problems: http://www.erik-krause.de/contrast

Posted by Alan Smithee on July 20th, 2005


Mendel Leisk wrote:
Why doesn't Vuescan have a "moderated" list somewhere?



Posted by Don on July 20th, 2005


On Wed, 20 Jul 2005 01:18:26 GMT, "Alan Smithee" <somewhere@asdf.com>
wrote:

Two reasons, really:

1. The author can't handle objective, fact-based reality.
2. The author can't be bothered with what users think or want.

!=> Even a semi-reputable software manufacturer would provide such a
forum on their site!

Oh yes, one more:

3. Most Vuescan "fans" prefer to shoot the bearer of bad news rather
than demand that (at least some of) the many Vuescan bugs be fixed.

There is the *unmoderated*:

alt.comp.periphs.scanners.vuescan

Also, I believe (but don't know for sure) that anyone can create a
Google group which can even be made by "invitation only" i.e. closed.

!=> Alternatively, one of the "many" alleged Vuescan "professional"
users could surely host such a forum on their company's site.

That would take a fraction of the effort they put into obsessively
attacking anyone daring to point out objective facts about Vuescan.

Either way, sounds like a excellent idea to me! ;o)

Don.

Posted by Roger S. on July 20th, 2005


Honestly a public forum would scare people away from Vuescan.
The latest version has significant cropping bugs with my scanner where
it forgets the cropping settings from prescan to scan and the IR fails
as well... That's progress!

Posted by Don on July 21st, 2005


On 20 Jul 2005 10:14:52 -0700, "Roger S." <rsmith02@gmail.com> wrote:

That's why the author was never keen on a dedicated public support
forum. Indeed, all that would do is expose even more Vuescan problems
and further demonstrate his inability to fix them.

Which is why he theatrically "resigned" from here so he doesn't have
to answer to such amateur bugs (like the one above) in the... what is
it now... *8th* major version?

Instead, he lurks and occasionally posts glorious praises to his own
program under a fake name...

Don.