I am puzzled by the 'lock exposure' and 'lock film base color' options
in Vuescan.
I have been scanning a Reala film and before starting went through the
steps os advanced workflow to lock the exposure and film base color.
It happens that one of the frames on the film is blank, so I expected
this to result in a uniform black image. Instead it is a very noisy
pink colour and non-uniform - darker in the bottom left and lighter in
the top right.
A selection of R,G,B colour values in the bottom left are:
163, 130, 141
152, 20, 117
100, 97, 149
170, 0, 138
202, 158, 190
and in the top right are
213, 111, 160
179, 150, 148
236, 210, 190
240, 171, 162
190, 255, 217
The green component inparticular seems to have a very large local
variation as well as varying from 0 to 255 across the diagonal.
Any help in understanding this would be appreciated. Also - why are
scans of negatives very much noisier than slides?
Tom
--
Tom Chisholm
(Remove 'falseteeth' to e-mail reply)
Glad you asked this quesion; I'm just getting started with Vuescan and
it's quite frankly driving me nuts! I am a software developer in my
'day job' and the user-interface of this program leaves a good deal to
be desired! Options appear and disappear for no directly intuitive
reason, and the instructions provided in the workflow guides seem to
be written with a lot of hidden assumptions!
Just now, I tried going through the advanced workflow for setting film
base exposure, as you are doing here, and I too got this exact same
'noisy pink' result. And now, I see the 'Lock Exposure' option, but
not the 'Lock Film base color' option - even when I go to 'More
Options | All'. A simple example of the confusing interface and/or
instructions are that you are told first to set "Input | More Options"
- set to what - 'some' or 'all'? There are two choices! Also, they
say 'If Input | Lock Film Base Color visible,...' - why may it not be
visible, and if it's not visible, how can you make it visible??!! A
more standard user-interface technique is to 'grey out' options that
are not contextually relevant in a given setting - much better than
disappearing them. This would also, possibly, remove the need to
'refresh' the left side of the user interface each time you change a
setting - very disconcerting!
So my negative had a bunch of 'pure black' shots (I rewound the film
before the end) so I have gobs of 'black' areas. I set 'white
balance' to 'none' based on the response below (thanks!). I turn off
'lock exposure', and I notice that 'lock film base to color' is
nowhere to be seen. I Press preview. Wait. I set a crop area to a
'black' area (unexposed frame). I press 'preview' again. Now,
magically, 'lock film base color' appears, and I check it. So I'm
done with the workflow as documented.
Now, I select an actual desired image frame on the preview screen.
What I see is a very dark preview of my image. So I go to the 'color'
tab, and select 'white balance'. Now my preview looks pretty good. So
I guess that was part of the issue? you turn off white bal, preview
twice and lock, then restore white balance, having locked in the film
base? If I go to 'More options | all', I can see a value of 2.101 for
RGB exposure, and 0.1% for exposure clipping. Does this seem normal?
And now, by the way, I can't seem to get rid of the 'lock film base
color' option ... I thought it disappeared after doing a preview, or a
scan, or something, but now I still see it! So what condition makes
it go away ...? very confused!
Anyway, after doing this, I get a 'pretty good' scan; nowhere near as
good as the image I got on print, nor the image they gave me on CD (I
get all my films processed/printed/burned to CD; this is just a test
of Vuescan and my scanner!).
On Mon, 21 Jul 2003 23:11:51 +0200, Erik Krause <erik.krause@gmx.de>
wrote:
===========
Reply to cschofie at domain dot com
Change domain to attbi to reply - Thanks
