As I mentioned this is a 2 part article.
Don
Hello friends--
I have read through Jon Cone's blogs. I have no comment on the part pertaining to the use of K7 inks to make standard positive inkjet prints. But the part pertaining to digital negatives was disappointing.
First, some background. In the normal use of QTR you only have to plug a small set of numbers into a textfile ( limit for each ink, crossover point where each lighter ink gives way and is supplanted by the next darker ink, and so forth) to completely specify how all the inks are used. With a little practice this textfile (.txt file ending) format is easy for human eyeballs to comprehend and work with. Then, when you install the textfile, a bunch of Roy Harrington's little subroutines take over, and based on the numbers you have plugged, compiles this information into specific instructions to be sent to the printer and which take over the job of smoothly blending one ink into the next.
This compiled information is in something called a .quad file and these files are found in a folder on your harddrive where QTR stores them. If you open one of these .quad files (drag its icon on top of the textfile icon on your toolbar) you will find something wondrous. Near the top you will see the letter K (for the dark black ink) with number after number ranging down below it. At the beginning these numbers are all zero, but if you scroll down you will begin to see increasingly large numbers until they stop. There are 100 of these numbers and each one specifies exactly how much K ink will be laid down at each percentage step of tonal value. Keep scrolling down. There will be 100 positions and values for the Y ink, the M ink and so forth for all of the printer's inks. If you have the mind of a Dalek, or like to immerse yourself in homemade Xcel spreadsheets (like Ben Altman -- hi Ben) you can skip the textfile part of QTR and write the .quad file yourself by laboriously typing in each number. But most of us find it far easier to work with the .txt files and let Roy's subroutines compile things into the .quad version.
Back to the Inkjet Mall inks. When Cone first started using QTR to print his inks he supplied profiles written in the human-friendly .txt format. In these files the limit for each of the seven inks was specified as well as the crossover number for each ink (ie, he wrote the profile as a seven part system). And, at the end, he applied one of Roy's linearization functions to fine tune and straighten everything out. But, at some point, he stopped supplying users with the human readable .txt file and instead only supplied the Dalek-friendly .quad version. Which means, you and I would find it extremely difficult to take one of his profiles and tweak it or rewrite it to make digital negatives. I have no idea why he did this.
Onward to K7 inks and digital negatives. If I were using QTR and the K7 inks to make digital negs, I would do pretty much what I do with the Epson UC inkset. I would move the dark ink limit up and down to set negative contrast, then fiddle with the limits of the lighter inks to get the midtones on my final print to be roughly linear (the tones on the negative would be definitely non-linear), and then I would apply a Photoshop correction curve to the Ink settings (not to the image file) to finish and fine tune linearization (I think and hope this is more or less the approach that Altman and King are taking). Cone does not do this. First, he fiddles his profile so that the inks print linearly on Pictorico (this is not a terribly useful step since the final negative will be, for most alt processes, decidedly non-linear). Then everything else is accomplished by applying a Photoshop correction curve to the image file. This is retrograde and ignores everything we have learned about making digital negatives in the last ten years. What is most sad is that this approach makes no use at all of the powerful tools available in QTR to set neg contrast and non-destructively linearize print midtones.
Is there any reason to mess with the K7 inkset for digital negatives? Sandy King seems to be hoping that the K7 inks will print to higher resolution than the Epson inks. That may be an issue with carbon printing, but it is definitely a non-issue with palladium and other matte prints. In principle, 7 overlapping inks should be able to print a very smooth and grain free negative (certainly everyone seems to agree that they make very nice positive prints). But, the way I use the Epson inks, I also have seven inks overlapping to various degrees (by having all the dark inks follow the K ink, and all the lighter inks follow the distribution of the LK ink). The Epson inks and QTR make very good negs and prints. But someday I would like to see a rigorous side by side comparison.
And, for myself, since I cannot afford the space to dedicate one printer just to negatives, using the Epson inks means I can print Xmas cards, my wife's bird prints, and other stuff as well as making good negs.
Sorry for the long post, but I just had to get this off my chest. Cheers, Ron Reeder