hi,
I am playing around with the module Negadoctor. However, trying to convert black and white negatives to positives, I keep getting a monochome photo with a color color cast (usually green or purple), no matter how I do it. The only workaround I found is activating color balance rgb and setting chroma to -100%.
What is going on here?
Thanks in advance
Anna
I think for many people it will be hard to give good advice without seeing the image and/or what you did. Maybe you consider sharing a RAW file and you will surely get some edits you can have a look at.
I use the colour balnace rgb for BW conversion after the negadoctor module, this does the trick 
this is also the only way I found to get decent results…
Negadoctor is trying to compensate for the color of the film base, which you need for color, but not b/w.
I’ve also seen this effect when setting negadoctor to black and white mode… I guess the issue is something different, maybe demosaicing?
@betazoid sorry a correction, I’m using the color calibration module for bw conversion!
how?
By just using the BW Delta 100 preset of color calbration. this goes before negadoctor (which is default anyway)
In essence I have the modules:
That does the trick
Edit:
For reference I added an image (CC-BY-SA) Ilford Delta 400 taken with Flexaret VI, developed in Moersch Eco Film Developer + the sidecar file
DSCF7194.RAF.xmp (7,0 KB)
DSCF7194.RAF (29,0 MB)
The Luminance-based preset seems to be suitable for all films that are not in the preset list, doesn’t it?
The preset is just a minor difference, You could just set the channels within the color calibration modules gray tab all to 1/3 and will get a “neutral” effect. But this will not change anything as the image is black and white to begin with.
I’m just using the preset because I’m lazy and it is faster to select.