Raw scan for ICC profiling

[r_moeller]

Hello

I try to get a raw scan form SilverFast Ai (V 6.0.2r37 for Nikon Super Coolscan 4000 ED) to create an ICC-Profile with a (third party) profiling tool. I use the following settings:

Frame:
Scan Type = 48 Bit HDR Color
Image Type = Standard or User definded with all choices checked and set to zero

Option / CMS:
CMS
Scanner -> Internal = NONE
Internal -> Monitor = Image Color Matching (ICM)
Internal -> Output = RGB
Profiles
Scanner = NONE
Internal = AdobeRGB1998
...
Rendering Intent = perceptual

= profile to embed - NONE

IMHO the scan should be raw as possible. But when I look at the Densitometer there are differences between the original and corrected values. It seems that some kind of postprocessing of the scan has taken place. Any informations or ideas?

Many thanks
Rainer

[degrub]

What did you do with gamma to embed for HDR and the for HDR checkbox ? Perhaps what you are seeing is a gamma adjustment ? You can set the gamma to 1 and check for HDR output and see if the densitometer values are constant.
Also see Ian Lyons' tutorial on setting up for output to HDR.

http://www.computer-darkroom.com/hdr_tutorial/hdr_1.htm


Frank

[r_moeller]

I have made my settings as mentioned by Ian Lyons. Only thing I have changed was the Image Type Setting (but from the manual I understand that this settings only apply by pressing the Auto Adjust button - not possible when HDR output is selected).

But your idea with gamma setting was a bit true. The fault was not the gamma settings under Option - it was the Histogram and Gamma setting under Tools. I am wondering if this behavior of Silverfast is by design!

If you use Histogram or Gamma tools in 48 Bit Color or 24 Bit Color and then switch to 48 Bit HDR Color this settings are stored and change the result of the HDR scan. Because of the disabled tool buttons you can't change the settings in HDR mode and also there is no warning like in other color modes (color of the button doesn't change to red)!

[degrub]

You might also try saving a "clean" frame set with the tool settings as you like them and then load that frame set when you want to scan a "raw" scan.
Otherwise i would turn in a problem report. They have had some similar problems with linked adjustments. See the development history under news.

Frank

[LSI_Magnussen]

Scan Type "48 Bit HDR Colour" will give you a raw scan without any corrections. But you have found a bug in the Densitometer that we were not aware of. It actually shows wrong corrected values when HDR output is selected - so sorry for the confusion, we will fix it in one of the next releases.

Ralf