What is your method for making digital negatives?

[joncone@cone-editions.com]

Sandy,

The software we built here to make QTR curves chooses 256 precise points from over 64,000 possible points for each of the seven curves that make up a single QTR K7 curve. As a result we do not have three edit points to allow for QTR editing. But, the result of such precision is output that is significantly smoother and as perfect as one can get in a linearized output.

The only curve I have made for digital negatives is for the Epson R2400 printer which produces 13" wide films. The curve is for Pictorico and produces a gamma 2.2 linearization from the dMin of the film to a dMax of nearly 2.9. Within that range of tone, you could build a Photoshop curve to limit the inks into a useful range of density as well as apply a contrast change that relates to your particular paper and chemistry.

The 2400 curve for film took me three days to build...and I ended up making two ink modifications to two shades which are easy to do on your own. I am certainly willing to share this with anyone who wishes to have a digital negative system. Unfortunately, the R2400 QTR driver is quite different than the 7600, 7800 or 7880... or other printers for that matter.

I do not know how other customers of mine are making their dig negs with K7 and they are not readily sharing their information.

The basics of using QTR tools is to build seven overlapping curves of density that are nearly linear and then to process them through the QTR tools for linearization. There is ample documentation on that process. However, there are very few instruments that can be used other than a densitometer for film. QTR attaches to the EyeOne spectro... And the EyeOne does not read film with the QTR tools. So there is the challenge to use hand entered data from a densitometer.

I happened to use an old x-rite autoscan that reads strip film but had to use a Mac with OS9 in order to have a functioning driver. We keep this old Mac just for this piece of outdated hardware.

Having said that, a lot of QTR users trying to make film negs are assuming that the work is done in Photoshop. The first step actually, is to configure QTR as a linearized process using QTR curves (which have no similarity to Photoshop curves, and serve no similar purpose.) The QTR curve controls the output of each of the inkjet heads...and you need all seven working in unison to produce a smooth output.

A reconditioned R2400 printer and my pictorico curve will give you a base that when printed with a gray tone scale - will produce a smooth artifact free gradation from dMin to dMax. It will provide a traditional opaque style negative (like silver) - rather than UV blocking...

How to get something like this for your 7600 - I'm not sure how the R2400 curve would translate into being modified - even though I can modify it easy enough. I can also give you the recipe for the two shades mixing... but it's not a definite because the QTR driver is so different between these two printers. I would think it could possible work.

When I made the R2400 neg system and announced to the thousands of Piezographers if there was interest to make turnkey neg systems...there were just a handful who wanted to use it. Not enough for the development time involved. Most people using Piezography are very happy with the output - especially the glossy systems which are true replicants for air dried silver print. I suppose I should have asked users who still had their darkrooms instead - the enthusiasm may have been higher.

I wish I could help you more directly with your particular printer. We no longer have functioning 7600 K7 printers either in our studio or the r&d lab - so I can't even offer to devote the time to making a K7 film curve for you.

If the person who is helping you requires some assistance - have him contact me.

Best regards,

Jon Cone
Piezography
http://www.inkjetmall.com

Matt,

I forgot to mention one thing about making digital negatives with K7 Piezography inks, and that is the fact that it is not possible to edit the K7 profiles with the regular QTR tools supplied by Roy Harrington. Instead, the K7 profiles were created by Vermong Inkjet with their own software, which I don't believe is available to an individual And even if it were Jon Cone suggests that editing the complex curves would not be feasible for most people.

At this time I have someone working with me in creating a digital negative profile for my carbon printing but it has turned out to be a fairly complicated endeavor. I must admit that had I know that the K7 profiles could not be edited with the regular QTR tool set I might have decided to stay with the Epson color ink set, or substitute that with the InkjetMall color ink set.

Sandy

[sanking]

Jon,

Thanks for your remarks. I have sent you a personal email about this.

I recognize that the profiling is complicated but it seems to me that it would be as easy to create good K7 profiles for digital negatives as for prints. You really only need three things. 1) linearize the output on Pictorico, 2) provide a user mechanism to adjust transmission Dmax for specific processes, and 3) provide a use mechanism for inserting a curve into the profile to linearize for speific processes.

Sandy

[Zero_Equals_Infinity]

Jon,

Thanks for your remarks. I have sent you a personal email about this.

I recognize that the profiling is complicated but it seems to me that it would be as easy to create good K7 profiles for digital negatives as for prints. You really only need three things. 1) linearize the output on Pictorico, 2) provide a user mechanism to adjust transmission Dmax for specific processes, and 3) provide a use mechanism for inserting a curve into the profile to linearize for speific processes.

Sandy

An old conversation, but a good one.

I suspect that choosing to use the closest one of Jon's curves (1.4 to 1.8) will get one very close with respect to proper Dmax. I might consider blending the two closest curves by applying a weight to the values in each curve if to obtain a curve that covers the full Dmin to Dmax range. (e.g. If I required a range of 1.76, I may derive a curve based on giving a weight of .6 to the 1.8 curve, and .4 to the 1.7 curve and summing for all values for each ink. Assuming no non-linearities between the two curves, that may work reasonably.) Alternatively, the error of using one curve is at most .05 (1/6) of a stop, and depending upon whether shadow or highlights is where I want to compromise, my exposure time could be altered accordingly. Linearization, could be realised by the usual method of measuring a printed step wedge and applying an inversion either in Photoshop as a final step before saving an image for printing through QTR, or to the values of the values of whichever of Jon's curves you are using. My inclination would be to use a Photoshop curve because I don't want to program a cubic spline interpolation into a C program to create a new curve. I suppose it would be easy enough, but I have not done that type of programming in years, and the interpolation would need to be applied to each ink curve which could cause it's own problems as the sum and the parts may deviate somewhat in practice. I won't make a distinction between the two linearizations you mention, as to me it is reducible to a linearization which takes into account the effects of the film and the process.

P.S. I just got the inkset installed for Method 3 yesterday, and hope to fun some step wedges through later today.

[sanking]

An old conversation, but a good one.

I suspect that choosing to use the closest one of Jon's curves (1.4 to 1.8) will get one very close with respect to proper Dmax. I might consider blending the two closest curves by applying a weight to the values in each curve if to obtain a curve that covers the full Dmin to Dmax range. (e.g. If I required a range of 1.76, I may derive a curve based on giving a weight of .6 to the 1.8 curve, and .4 to the 1.7 curve and summing for all values for each ink. Assuming no non-linearities between the two curves, that may work reasonably.) Alternatively, the error of using one curve is at most .05 (1/6) of a stop, and depending upon whether shadow or highlights is where I want to compromise, my exposure time could be altered accordingly. Linearization, could be realised by the usual method of measuring a printed step wedge and applying an inversion either in Photoshop as a final step before saving an image for printing through QTR, or to the values of the values of whichever of Jon's curves you are using. My inclination would be to use a Photoshop curve because I don't want to program a cubic spline interpolation into a C program to create a new curve. I suppose it would be easy enough, but I have not done that type of programming in years, and the interpolation would need to be applied to each ink curve which could cause it's own problems as the sum and the parts may deviate somewhat in practice. I won't make a distinction between the two linearizations you mention, as to me it is reducible to a linearization which takes into account the effects of the film and the process.

P.S. I just got the inkset installed for Method 3 yesterday, and hope to fun some step wedges through later today.

In practice Method 3 works well for making digital negatives, using an .acv curve for final linearization. The range of contrast in the profiles provided by Jon Cone is quite wide, and that together with the fact that there is always some control of contrast with process, makes it pretty easy to choose and adapt the right profile.

Sandy

[neil poulsen]

Max,

I feel confident that you could make good digital negatives with QTR and the K7 selenium/warm neutral gloss set. The problem is I don't know anyone who is doing this so you will have to start from scratch in making your profile with QTR. You might have noticed that I am currently working on a profile myself for digital negatives the Epson 7600 and the K7 selenium set, though I am trying to use the matte black as I would also like to use the printer for making matte digital inkjet prints. The idea of using four to seven shades of gray to make a digital negative has in theory some clear advantages, but to translate this to reality may take some work.

PDN is a multi-component system and you could use parts of it regardless of the ink set in the printer, but in practice it is designed as a complete workflow where you are using color inks and the Epson driver.

Sandy

Sandy,

Have you encountered with your 7600 the artifact of "gradation lines" that run perpendicular to the print head travel in continuous tone prints with the 7600? (Prints w/smooth gradations.) This artifact supposedly occurred with the earlier Epson 2400, 2200, 4000, 7600, etc., printers. The R1800 (or R1900?) and the 3800 printers did not show this artifact. I sure saw it with my 4000. It was my understanding from Bostick-Sullivan that this artifact was an early printer issue seen in printing digital negatives that was not apparent in standard printing on paper.

They were seen in continuous tone prints from digital negatives, like portraits with smooth backgrounds, because the artifact was faint enough to be camouflaged by prints with more complex subject matter.

[neil poulsen]

I took a workshop from and used Dan Burkholder's method for creating digital negatives. He's the person who popularized digital negatives and did a lot of the early development work. I got some nice results from this and even made a few negatives for another pt-pd printer. After printing, they came out really nice. This included methods for pt-pd, cyanotypes, maybe some others now.

If you purchase his CD, it contains the curves he himself developed for some of the standard printers used to make digital negatives. (e.g. 3800 and 3880, 2200, 2400, etc.) So, there isn't the testing needed for other methods. The primary emphasis in his class and from his book and the CD is learning how to apply the curves in he developed in Photoshop.

It makes for a good start in printing digital negatives. One could try more advanced methods QTR, PDN, etc., later on.

[sanking]

Sandy,

Have you encountered with your 7600 the artifact of "gradation lines" that run perpendicular to the print head travel in continuous tone prints with the 7600? (Prints w/smooth gradations.) This artifact supposedly occurred with the earlier Epson 2400, 2200, 4000, 7600, etc., printers. The R1800 (or R1900?) and the 3800 printers did not show this artifact. I sure saw it with my 4000. It was my understanding from Bostick-Sullivan that this artifact was an early printer issue seen in printing digital negatives that was not apparent in standard printing on paper.

They were seen in continuous tone prints from digital negatives, like portraits with smooth backgrounds, because the artifact was faint enough to be camouflaged by prints with more complex subject matter.

Yes, I have encountered the banding that runs perpendicular to the print head when using the Epson 7600, and the 2200 and 4000. Curiously, these printers make perfect B&W monochrome prints, but when you invert the values and print on Pictorico or some other OHP you see the lines. This makes it difficult, if not impossible, to make acceptable digital negatives with subjects that have large areas of smooth tonal values, say sky or portraits. Fortunately most of the current generation of printers beginning with the x800 series, do not give this type of banding.

At this time I have my 7600 set up with a K7 Cone ink set, and it produces great monochrome prints on papers. But I use the 3880 for making digital negatives. At some point I am going to replace the 7600 with an 8 or 9 slot Epson printer that will allow me to make both K7 prints on paper and digital negatives without swapping out the cartridges.

Sandy

[bob carnie]

Hi Sandy

When you come to TO for the course you are running we will have a Epson 7800 for you to use with the class. Ron Reeder will be in the week before you and he will set it up for us.
I am hoping to have him help me with the Lambda silver negs before you get here so you can give that a go after the workshop if you like.

info on our workshops are at www.defendthedarkroom.ca

Bob

[sanking]

Hi Bob,

The 7800 will work fine for digital negatives. If I could fine one locally with low use at a good price I would grab it for myself.

Offering the Lambda silver negatives will be a good service if you can get that up and running.

Sandy

[bob carnie]

We should be ready by the time so you can tag an extra day and make a neg or two to take back to your darkroom .

Hi Bob,

The 7800 will work fine for digital negatives. If I could fine one locally with low use at a good price I would grab it for myself.

Offering the Lambda silver negatives will be a good service if you can get that up and running.

Sandy