Vuescan output density range

[Robert Feinman]

Once again I've confused myself about what the various color
modes do in Vuescan.
My preferred workflow (at least for slides) is to set all the
Vuescan parameters to a fixed value with no black & white point
clipping and then create a scanner profile (with Monaco EZcolor).
Then for scanning I leave all the scanner values the same do
the scan and in Photoshop apply the scanner profile and then
convert to working (Adobe RGB) color space.
The problem arises with the color tab settings. If I choose
"none" then I get a fairly dark, flat preview as expected.
However, the final scan still has the dynamic range spread out
compared to the preview
If I choose "manual" I get the final scan range reaching 0 and
255.
With a true color profile not only is the gray scale range adjusted
for, but individual color values are corrected as well. So, if the
scanner shifts these, the profile conversion will fix the wrong
values.
Thus, the question is, how do I get Vuescan to just scan and not alter
the values between preview and final scan?

 

[Mike G.]

Once again I've confused myself about what the various color
modes do in Vuescan.
My preferred workflow (at least for slides) is to set all the
Vuescan parameters to a fixed value with no black & white point
clipping and then create a scanner profile (with Monaco EZcolor).
Then for scanning I leave all the scanner values the same do
the scan and in Photoshop apply the scanner profile and then
convert to working (Adobe RGB) color space.
The problem arises with the color tab settings. If I choose
"none" then I get a fairly dark, flat preview as expected.
However, the final scan still has the dynamic range spread out
compared to the preview
If I choose "manual" I get the final scan range reaching 0 and
255.
With a true color profile not only is the gray scale range adjusted
for, but individual color values are corrected as well. So, if the
scanner shifts these, the profile conversion will fix the wrong
values.
Thus, the question is, how do I get Vuescan to just scan and not alter
the values between preview and final scan?

I'm not positive I understand your entire question, but if in fact it
distills down to your last sentence, then I believe that checking the
'Lock Image Color' checkbox on the 'Input' tab will do that. I'm still
running v7.6.x, so I don't know if it's called that in the v8.1 interface.

 

[Wilfred]

I'm not positive I understand your entire question, but if in fact it
distills down to your last sentence, then I believe that checking the
'Lock Image Color' checkbox on the 'Input' tab will do that. I'm still
running v7.6.x, so I don't know if it's called that in the v8.1 interface.

It's called the same in 8.1.
I think it's also important that you 'freeze' VueScan's exposure
settings by using Lock Image Color *before* you profile the scanner with
external profilig software . Also I think you'll have to set color
correction to 'none'(in fact you're calibrating you scanner plus VueScan
in a specific setting). Then save this setting as a .ini file and use it
everytime you want to use the Monaco profile.
The disadvantage of using external profiles is that your profiling
target may not cover the complete range that can be present in other
slides. Colors that are outside the range of your target may not be
covered by the profile, and the locked exposure settings may not be able
to squeeze these colors out of other slides (if present).
As far as I have understood it, VueScan's own matrix-based profiles are
able to cope with different exposure settings, so you don't have to lock
exposure. In recent versions of VueScan, I found these profiles to give
excellent results when scanning slides.
With older versions of VueScan this wasn't the case. These profiles
don't work with negatives either IMO - VueScan's 'built-in' profile
gives better results.