Re: How to translate log density readings to percent?

MessageLoris,

You do not need to map (Dmin, Dmax) to (0%, 100%). The values you have for R and 1-R are already in percentage.

That is, if you subtract the real Dmin (0.12) and consider Dmin to be 0, then at density of 1.33 the reflectance is 4.68%; the opacity is 95.32%. You do not map that to 100%. That would be incorrect.

Dave S
  ----- Original Message -----
  From: Loris Medici
  To: alt-photo-process-l@sask.usask.ca
  Sent: Tuesday, September 07, 2004 6:31 AM
  Subject: RE: How to translate log density readings to percent?

  I made a mistake and sent my previous message prematurely:

  .
  .
  .

  Mapped column formula is = ( 1 - R' ) / 95.32

  OR, is it as simple as:

  % = reading' / dmax'

  Thanks,
  Loris.

    -----Original Message-----
    From: Loris Medici [mailto:loris_medici@mynet.com]
    Sent: Tuesday, September 07, 2004 1:20 PM
    To: 'alt-photo-process-l@sask.usask.ca'
    Subject: How to translate log density readings to percent?

    d = log ( 1 / R )

    d: log density
    R: reflectance (%)

    =>

    R = 1 / ( 10 ^ d )

          d' R' 1 - R' Mapped
          1 - R'
          0,00 100,00 0,00 0,00
          0,30 50,12 49,88 52,33
          0,84 14,45 85,55 89,74
          1,33 4,68 95,32 100,00
Received on Tue Sep 7 10:36:27 2004