Pages: « 1 2 3 [4]   Bottom of Page
 Author Topic: Colormanaging scanned negatives - How to do best ?  (Read 8790 times)
Mark D Segal
Contributor
Sr. Member

Offline

Posts: 7126

 « Reply #60 on: February 22, 2012, 11:03:13 AM » Reply

It appears applying a high gamma as I did comes close to what happens if the white point has been set properly. .

Could be - looking forward to what you find.

And yes, the black point should be remapped to neutral black by removing the mask if done from unexposed film.
 Logged

Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
Christoph C. Feldhaim
Sr. Member

Offline

Posts: 2509

There is no rule! No - wait ...

 « Reply #61 on: February 22, 2012, 02:19:24 PM » Reply

I have played a bit with the gamma and the transformation a linear curve can get by applying gamma.

The formulas:

Code:
Gamma (Yellow):  y= x^Gamma

Red linear:    y= 0.8x+0.10
Green linear:  y= 0.8x+0.20
Blue linear:   y= 0.8x+0.25

Red corrected curve:   y=0.10-(0.8x+0.10)^Gamma
Green corrected curve: y=0.20-(0.8x+0.20)^Gamma
Blue corrected curve:  y=0.25-(0.8x+0.25)^Gamma

I have not yet an  idea what it means, nor am I sure if have applied correct x and y values, but if I'm not mistaken values from gamma acrobatics are normalized to values between 0 and 1.
This is as a help for thinking what might have happened above.
No idea if it has any declarative value.
I also am not sure if I did the subtraction correctly.

Ideas about the formulas?

(Rendering done with POVRay 3.7 beta)
 « Last Edit: February 22, 2012, 02:22:57 PM by Christoph C. Feldhaim » Logged

 Pages: « 1 2 3 [4]   Top of Page