Scanning B&W glass negatives

[Akominatus]

Does anyone have any suggestions or hints about scanning b&W glass negatives from the 1920s?

In particular, is it best to scan as positive and then Invert the resultant (negative) image in Photoshop, or scan as negative to give a positive image in Photoshop? My first experiments seem to suggest that inverting a negative image gives extremely thin, low contrast images...

Finally, what about the vexed question of Grayscale v. RGB in this case?

Thanks in advance, and apologies if I've missed any previous discussions of the subject.

[RAG]

Akominatus,

I have not scanned a glass negative so I can't tell you the best method regarding Negative or Positive, but you should go with RGB Vs Grayscale in any case.

[Akominatus]

Leaving aside the question of the glass support, would the recommended path for going from a b&w negative to a positive be the following then:

Scan positive RGB (i.e., producing a negative image onscreen);
Invert in Photoshop;
Use Chanel Mixer to select optimum greys.

Or not...?

[RAG]

Well,

I'm not sure if you should use positive or negative scanning for glass slides, but the use of Channel Mixer is one method for converting to an optimum B&W image.

[asto999]

I have tried both.

However, my favourite approach is to scan the glass negative as a negative, but in RGB mode.

Probably the lack of contrast and the "thin" appearance is due to a not so well developed negativ, or - maybe - the negativ has thinned out over the decades due to rests of fixing agent in it.

You could try to use the histogram tool to adapt the range of your image.

And it seems to me always the best to scan in RGB and convert to B/W only then necessary, later in Photoshop.

Good luck!
Armin.