How does VueScan Compute Optical Density?

  • Thread starter Thread starter Alan Smithee
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A

Alan Smithee

How does Vuescan manage to compute optical density. Why can't I do this from
Photoshop?
 
Alan Smithee said:
How does Vuescan manage to compute optical density.
Click to expand...

Vuescan actually displays Density relative to the brightest pixel of
the Raw scan data, the brightest pixel representing Density=0.00. The
calculation is Density=Log10(Brightest/actual), and this is calculated
per channel.

To be complete, true *Optical* Density is calculated relative to the
lightsource, but Vuescan cannot know the lightsource's brightness with
the sofar unknown film(base) density.
Why can't I do this from Photoshop?
Click to expand...

Dunno for sure. Maybe because Photoshop used to be a more (pre-)press
oriented application.

Bart
 
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