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Re: filmscanners: Vuescan color spaces (long)

From: "shAf" <michael@shaffer.net> To: <filmscanners@halftone.co.uk>
Sent: Monday, April 02, 2001 4:45 PM

> Mark writes ...
> > From: "shAf" <michael@shaffer.net> To: "film scanner list"
> > <filmscanners@halftone.co.uk> Sent: Saturday, March 31, 2001 5:55 AM
> >
> >
> > > What is more ... Ed informs me there is no such internal
> > > color space as "VS RGB"... Vuescan simply carries scanned
> > > RGB from the device to any of the selectable "color
> > > spaces".  The scanners are characterized, recognized if
> > > on line, or selectble from the "device|mode" list if
> > > scanning from a raw file.
> >
> >
> > How is the the conversion from the raw scanner RGB to a
> > selectable "color Spaces" like Adobe RGB taken place?
> > In ICC colormanagement you need two profiles (and a
> > conversion engine), a source and a target profile,
> > .... Which source profile does Vuescan use? Or is
> > Vuescan just assigning a color space to the raw
> > scanner RGB? ...
> Vuescan does not simply assign ... if it did, each image given a
> different color space would appear different in Photoshop ... rather,
> they all appear exactly the same, so Vuescan is doing something right.
> The source profile has the to be the "characterization" I mention
> above.  It is most likely a simple matrix type profile as determined
> by Ed, which also takes into account selectable film type.  This is
> speculation on my part, but I don't believe Ed uses a "conversion
> engine", rather a mathematical matrix transform.  If he created LUT
> type device profiles I believe he'd need a conversion engine (Adobe,
> Kodak, etc).  I wish it were the latter because LUT (3D) device
> profiles can accommodate a larger and more accurate device gamut.


It is of no use to speculate, better ask Ed if you want to know. Vuescan
does something to the raw scanner RGB to convert it to the known color
spaces like Adobe RGB. It is probably not the usable ICC Color Management
procedure. If it works its oke. If it is not Vuesan always have the "Device
RGB" option. Thats why this option can be important.

Regards, Mark


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