Re: using a scanner as a densitometer?

Say . . this is a fascinating topic that I'd like to learn more about.
How do we go about it on this list?
Jack Fulton

On February2006, at 11:09 AM, Ender100@aol.com wrote:

> It is not too difficult to get fairly accurate densitometer
> readings from your scanner, as long as you have a standard
> reflection step tablet to use as your standard comparison—these are
> available from Stouffers.
>
> I included this feature in the new PDN Curve Calculator II just as
> an added tool and it is surprisingly accurate—compared to my
> reflection densitometer the values varied no more than about Log .
> 02 reflection density. You just enter a measured value between 0
> and 255 and the software converts it to a Log value for you.
>
> The main trick is setting black and white endpoints properly using
> the reflection steptablet and then saving that setting to use later
> with whatever you are measuring. You then compare the Photoshop
> Values of the print densities you are measuring to the known values
> of the reflection step tablet. You can easily create an Excel
> Spreadsheet that will convert this data for you.
>
> Note that the maximum value on the Stouffers is Log 2.0 reflection,
> so unless someone knows of a reflection steptablet that goes above
> that value, you are limited to values between Log .03 and Log 2.0
> when using this method.
>
> Best Wishes,
> Mark I. Nelson
> www.MarkINelsonPhoto.com
> www.PrecisionDigitalNegatives.com
> PDNPrint Forum @ Yahoo Groups
Received on Wed Feb 22 19:03:03 2006