QTR-Quadtone RIP

It looks like the device you have is reading RGB density. The x-rite
810 (that I have) also does this. In the case of the 810, the density
readings are performed according to a standard called Status-A density
readings. The 810 also will take Visual density readings. These are
the usual density values we refer to in BW printing. I have not been
able to find a way to mathematically relate RGB density to Visual
density. I tried simple averaging and various more complicated
correlation techniques. Nothing was satisfactory. I quit looking once
I realized that the Status-A RGB values bear no relationship to the
RGB values used by Photoshop, for example.

Your best bet would be to determine if there is a setting on your
densitometer for Visual density.

Tom Moore

--- In QuadtoneRIP@yahoogroups.com, "andywebsterus" <andy@...> wrote:
>
> OK I know I'm answering my own posts!
> 
> > Toolcrib will auto-paste these values into Excel....  (looked like
I was 
> > getting somewhere) like this:
> > 
> > MGI RD-200 000255 
> 
> The useful part of this string are the values:
>  
> 00095B          00077A              00301A
> 
> They are R-G-B as HEX values.
> 
> I can get all the measurements neatly and automatically into Excel, 
> (each click on the densi pastes another reading into the sheet) then 
> converted to decimal.  The lower the number the more reflective the 
> surface.
> 
> 
> How do I convert these  decimal RGB values into something that QTR 
> will enjoy?
> 
> RGB to L ?  How to do that?
> 
>  I Have an IT8 target (Wolf Faust) which I might be able to use to
check 
> calibration...
> 
> Andy
>