RE: filmscanners: VueScan Histogram

["Jawed Ashraf" <Jawed@cupidity.force9.co.uk>]

Adobe RGB has (ironically enough, this is after all a "Mac" company!) a
built-in gamma of 2.2.  Therefore on a Mac operating at gamma 1.8, with an
application (Vuescan?) that isn't performing any translation of the image
from source colour space into monitor colour space, Adobe RGB will look
"wrong".  Not to mention that Adobe RGB also has a larger gamut than
monitors can show.  So, not only does the image look wrong tonally, but
saturation is also incorrect.

Obviously, when an image in Adobe RGB is viewed in a profile-aware
application, such as Photoshop, a translation to the monitor gamut *and*
gamma is performed.  So in these circumstances the image will look "right".
Except there's a chance that some extremely saturated colours (I think
yellows are problematic on monitors) will be noticeably "wrong".   It is
simply because the monitor can't cope.

Jawed

> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Julian
> Vrieslander
> Sent: 16 December 2001 17:32
> To: filmscanners@halftone.co.uk
> Subject: Re: filmscanners: VueScan Histogram
>
>
> On 12/16/01 8:03 AM, David Gordon <mail@davidgordon.co.uk>, wrote:
>
> >Julian Vrieslander [julianv@mindspring.com] wrote on Sat, 15 Dec
> >2001 00:33:41 -0500
> >
> >>Maybe with more experience I will get better at inspecting VueScan's
> >>displays and choosing the right values for WP, BP, and gamma.
> But since
> >>these displays are not color managed, I also have to mentally
> compensate
> >>for how the image appearance is going to change when it goes into
> >>Photoshop.
> >
> >What I see in the VueScan window is what I get in Photoshop - am I doing
> >something right!
>
> Maybe you are running on a PC and using sRGB as your color space.  If so,
> a color managed display is less important.  I run on a Mac with a gamma
> 1.8 monitor, and I prefer to use Adobe RGB as my color space.  With
> VueScan set to Adobe RGB, images appear very different than how they
> appear in Photoshop: the VueScan version is very flat and desaturated.
>
> I've figured out a workflow that gives me a somewhat more useful display
> in VueScan.  I set color space to Apple RGB and gamma 1.8 for my first
> look at the scan.  I set crop, exposure, white point, black point,
> brightness, and filter options, using Prev Mem and Scan Mem to check
> results in Apple RGB.  Then I change to Adobe RGB and gamma 2.2 (keeping
> other settings the same), and I do a Scan Mem to write the final output
> file.  This two-space two-step takes extra time, and it still does not
> give a really good match with what I see in Photoshop.  But it's the best
> I can do with the current version of VueScan.
>
> --
> Julian Vrieslander <mailto:julianv@mindspring.com>
>
>