The linearization data in your profile have such a low slope that you're close to the point where QTR will reject the data.
The slope (gama) is shaped to correspond to density range. In the Carbon 100 profile I posted the DMax is about log 2.05, designed for the contrast of the sensitizer which is determined by strength of the dichromate. A profile for a pure palladium print would require a much higher gamma to give a Dmax of about log 2.8 or more. There are significant differences in curve type between a palladium print (long toe, compressed shoulder) and a carbon print (fairly straighly line from toe to shoulder) but I have never had any trouble using LINEARIZE with the data so long as process itself was up to par.
The slope (gama) is shaped to correspond to density range. In the Carbon 100 profile I posted the DMax is about log 2.05, designed for the contrast of the sensitizer which is determined by strength of the dichromate. A profile for a pure palladium print would require a much higher gamma to give a Dmax of about log 2.8 or more. There are significant differences in curve type between a palladium print (long toe, compressed shoulder) and a carbon print (fairly straighly line from toe to shoulder) but I have never had any trouble using LINEARIZE with the data so long as process itself was up to par.
I'm
curious why the linearization data is from dark to light. I had to
reverse the order to get QTR to accept it. I'm on Windows, but I
thought QTR was the same with respect to this issue for both platforms.
The linearization data in my profiles for digital negatives is reversed compared to profiles for inkjet positives.
The linearization data in my profiles for digital negatives is reversed compared to profiles for inkjet positives.
I
would be curious to see scans of the highlights of prints made with
this sample curve. Much of what we do with partitioning is to "hide the
dots" in the highlights. When the image in inverted, I'm not sure what
the differences are going to be. The platinum print is so rough, I
doubt anything will show.
Highlights are quite smooth, just a tad grainier than with my all gray ink set.
Highlights are quite smooth, just a tad grainier than with my all gray ink set.
What
papers are you using that are as smooth as the base for the silver
print? I work with a lot of watercolor painters and have found that
Arches Hot Press is about the best, but then I'm also rejecting
many/most papers based on poor dmax results when printed directly with
the carbon. That is an issue your carbon process may not be concerned
with.
My carbon transfer prints are placed on both I fixed out silver papers (glossy and matte surfaces) as well as gelatin or gelatin + albumen sized art papers. Dmax with most of my prints ranges from a low of about log 1.7 to a high of about 2.2. It depends on both the substrate/final support and the gloss/matte nature of the tissue.
My carbon transfer prints are placed on both I fixed out silver papers (glossy and matte surfaces) as well as gelatin or gelatin + albumen sized art papers. Dmax with most of my prints ranges from a low of about log 1.7 to a high of about 2.2. It depends on both the substrate/final support and the gloss/matte nature of the tissue.
Do you stay with the straight line CURVE_K= "0;0 100;100" and copy curves for the inks?
I would just put the input/output numbers for an .acv curve to replace the current straight line, then all of the other curves follow the K.
I would just put the input/output numbers for an .acv curve to replace the current straight line, then all of the other curves follow the K.
Many people I know use a film scanner to creat an .acv correction curve. It works reasonably well, but I find that I get better results with the iOne.
One
thing that I have found with film scanners is that it's hard if not
impossible to stop them -- or at least their OEM drivers -- from
applying a built in profile. This can significantly compress the dark
end of the curve. I try to use manual exposure and pull the sliders out
to the max to try an avoid the effects of this. It's hard to say how
successful this approach is.
I always use manual exposure, pull the sliders to just avoid clipping data, set the gama to 1.0, and set input output to 0 and 250. Even so, I get much better results with the iOne, but using LINEARIZE can be very difficult for hand coated processes because if any of the values are out of order the necessary curve can not be created.
Sandy
I always use manual exposure, pull the sliders to just avoid clipping data, set the gama to 1.0, and set input output to 0 and 250. Even so, I get much better results with the iOne, but using LINEARIZE can be very difficult for hand coated processes because if any of the values are out of order the necessary curve can not be created.
Sandy