Digital BW, The Print

An amber Wratten 106 is used as the 'visual' filter in Macbeth
densitometers (and maybe others) to make the spectral response of the
sensor simulate that of the eye. The 106 allows almost all the red,
some green and a little blue through. However, that in itself isn't
enough information without knowing the spectral characteristics of
everything else.

I just did a few quick tests on the Status A RGB and Visual density
data I have readily available, and I go a reasonable match when

Dvis = 0.3*R + 0.55*G + 0.15*B 

That doesn't mean that it is correct, just that it might be close
enough in the absence of better information.

Depending on where you are, why not look around for a cheap
densitometer that has a visual channel, or better still, buy a
PrintFix Pro on eBay.

Best,
Helen

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "joejx8"
<joejx8@...> wrote:
>
> 
> Hi,
> 
> I am intended to buy an old/used densitometer. I have seen a model 
> which seems to measure only R,G,B *density*. 
> 
> Is there a mean to get a BW *density* value (by calculation) from R,G,B 
> density values... I was thinking at a formula like DBW= 0,7*DR + 0,2*DG 
> + 0,1*DB  (values are just for illustration) ?
> 
> Thanks !
> 
> J.
>