Quad Tone RIP

[donbga]

Is anyone using QTR to make digital negatives? If so can or would you spare any details about what you are doing with this RIP (or any other for that matter) ?

Don Bryant

 

[mkochsch]

New Book

http://www.ronreeder.com/articles/digitalnegs.html

Just in time for Xmas. I've not delved into the curve builder yet, but I looks like it must work if someone has written a section of a book devoted to it...I'm going to try building some curves shortly I'll keep you posted.

 

[Nathan Jones]

Merry Christmas, in deed. This looks interesting.

Don, I picked up QTR because of the ink control options in it. ---That was just before I dropped my PDN calibration work with Azo G3 (first due to lack of Amidol, and then the paper itself, as you know, dissappeared). (I am very pleased with this RIP for printing "inkjet premonitions.") I am getting set up to resume work with PDN on palladium, so I am equally interested to know other's experience with QTR making digital negatives.

 

[Greg_E]

You might also want to look into the Bowhaus RIP IJC/OPM. the GUI is a bit more friendly, which translates to easier use. It is of course more expensive. http://www.bowhaus.com/services/IJCOPMmain.php4

 

[Helen B]

I started to test some IJC/OPM profiles for making digital negatives directly from positive images (ie 'inverted' profiles) but got distracted when the K3 inks came out.

Last week I discovered by chance that I could print using a mixture of MIS base, Windex and red dye (from a stamp pad refill - I had to dye the cleaning mixture to see the nozzle test patterns) with an Epson 2200 that wouldn't print with OEM ink. Even after getting perfect prints with the dye, the clogged nozzles wouldn't print with OEM ink. This means that I now have a 2200 that can't be relied upon to print normally, but which seems perfectly capable of printing red dye images. I will resume my tests.

Best,
Helen

 

[donbga]

http://www.ronreeder.com/articles/digitalnegs.html

Just in time for Xmas. I've not delved into the curve builder yet, but I looks like it must work if someone has written a section of a book devoted to it...I'm going to try building some curves shortly I'll keep you posted.

Interesting, perhaps Ole Saint Nick will drop me off a copy.

Don Bryant

 

[donbga]

Merry Christmas, in deed. This looks interesting.

Don, I picked up QTR because of the ink control options in it.

Yes I like the ink control options and have wondered how QTR might be able to be used for making digital negatives. However I prefer colorized negatives to black only.

Don Bryant

 

[Kees]

Yes I like the ink control options and have wondered how QTR might be able to be used for making digital negatives. However I prefer colorized negatives to black only.

Don Bryant

Don, colorized negatives can be made with QTR too. I've set up a printer with QuadToneRip that can print monochrome C, M, Y, K, CY, CM and mixes of two of these colors. For each color I made a QTR setup C and M are made with C and LC or M and LM. CM is a four color mix. CY a three color mix.

For salted paper and albumen I am using CY as printing color. These prints are green. For printing van dyke and cyanotype I take down the ink load percentage in the driver. Of course each process has it's own correctioncurve, but you can integrate these in the QTR setup for each process/color. For short scale techniques like gum I am using 90% CM with 10%Y (purple negatives).

With a dedicated black and white printer I get excellent results on Agfa CopyJet with QuadToneRip by using only grey inks (no K).

 

[donbga]

Kees,

I've gone through the process of linearizing curves with QTR but I cannot wrap my brain around how to use color inks excluding black inks from the printing process. But even more importantly how would one decide which inks to use?

Don Bryant

 

[donbga]

You might also want to look into the Bowhaus RIP IJC/OPM. the GUI is a bit more friendly, which translates to easier use. It is of course more expensive. http://www.bowhaus.com/services/IJCOPMmain.php4

I'm sure this is a great product but how would one use it for making digital negatives?

Don Bryant

 

[mkochsch]

Kees,

I've gone through the process of linearizing curves with QTR but I cannot wrap my brain around how to use color inks excluding black inks from the printing process. But even more importantly how would one decide which inks to use?

Don Bryant

One method is to use the colours on the fringes on the RGB colour model. Imagine a cube. X, Y and Z planes of the cube each represent RGB respectively. Imagine the cube is 256 blocks in each direction. Pure Reds, Greens and Blues (and their off-spring) only exist on the edge corners of the shell of the cube.

View attachment 9

The goal is to avoid using the "dirty" black ink that inhabits the centre of the cube. This -- in theory -- produces a better pattern of dots on the negative -- according so some.
Deciding which inks to use is easy. Print a step wedge(s) that shows each of the colour combinations in the area of the cube I just mentioned. Usually, one or two ink combinations will produce a square white enough for the dMax of your emulsion. I'll send you one if you want.

 

[Nathan Jones]

Yes I like the ink control options and have wondered how QTR might be able to be used for making digital negatives. However I prefer colorized negatives to black only.

Don Bryant

Yes, Don, it was my intention to exclude the blacks and print colorized negatives (ala PDN). It sounds like I got about to the point where you are now.

Until the next time,

 

[donbga]

One method is to use the colours on the fringes on the RGB colour model. Imagine a cube. X, Y and Z planes of the cube each represent RGB respectively. Imagine the cube is 256 blocks in each direction. Pure Reds, Greens and Blues (and their off-spring) only exist on the edge corners of the shell of the cube.

View attachment 9

The goal is to avoid using the "dirty" black ink that inhabits the centre of the cube. This -- in theory -- produces a better pattern of dots on the negative -- according so some.
Deciding which inks to use is easy. Print a step wedge(s) that shows each of the colour combinations in the area of the cube I just mentioned. Usually, one or two ink combinations will produce a square white enough for the dMax of your emulsion. I'll send you one if you want.

Michael,

The Rubic's cube approach sounds interesting but I'm not sure I understand how to combind that image with QTR. Sometimes I'm a bit slow, perhaps I'm missing the obvious. But please e-mail me a copy of the cube image.

Thanks,

Don

 

[Kees]

Kees,

I've gone through the process of linearizing curves with QTR but I cannot wrap my brain around how to use color inks excluding black inks from the printing process. But even more importantly how would one decide which inks to use?

Don Bryant

Did you make your own QTR curves too? When you download QTR there is a Curvedesign folder included. I'm using a mac, so maybe this might be a bit different on windows. When you open the Curvedesign folder you find instructions to edit the default inkdescriptor files for your printer. Here you can specify how many inks you use, in what order these inks are used and where each ink takes over from the previous. You can also print a calibration print for this file to help you decide how to edit the inkdescriptor file.

When you run the installerscript with the edited file a new QTR printerprofile/curve is created that you can choose from the QTR driver. After this you can linearize or make a correctioncurve for each process.

The green (CY) negatives have most contrast, Magenta-Yellow (MY) has a bit less contrast and purple CM is low contrast. You can mix in some extra yellow or magenta to finetune from the driver where you can choose two profiles and mix them.

Here is an example of my CM inkdescriptor file: CM.txt
I use the normal ink description for the first inkcolor and the toner description position for the other.

Maybe a windows QTR user can tell if this works the same on windows.
Hope this gets you on the way!

kees

 

[clay]

I wrote a brief non-technical article for alternativephotography.com that uses the idea of a ternary graph to determine the appropriate mix of colors that block the most Uv (or other) light. It could easily be adapted to CMY space as well (no black). My RGB approach does, of course, use a little black, but the negativesand resulting prints are as good as any I have seen from other approaches.

http://www.alternativephotography.com/articles/art056.html

 

[menglert]

I downloaded QTR to look at the different settings. There were different algorithms available to choose from, and I wondered if this solved the Venetian blind problem, some of the Epson printers were having?

Also, are there any other printer RIPs available that would allow me to control ink density and print head passes as the R2400 drivers do? I am using an R800.

Regards,
Martin

 

[Nathan Jones]

I also was drawn to QTR because of the variable algorithms and the prospect of this option to resolve banding issues. The wonderful thing about QTR is that its shareware. Other RIPs I looked at were quite expensive.

 

[menglert]

So does this take care of the banding/venetian blind problem?

Regards,
Martin

 

[Greg_E]

I'm sure this is a great product but how would one use it for making digital negatives?

Don Bryant

It does the exact same things that QTR does, except has a better GUI for setting the ink mixing.

 

[donbga]

Did you make your own QTR curves too?

Yes.

When you download QTR there is a Curvedesign folder included. I'm using a mac, so maybe this might be a bit different on windows. When you open the Curvedesign folder you find instructions to edit the default inkdescriptor files for your printer. Here you can specify how many inks you use, in what order these inks are used and where each ink takes over from the previous. You can also print a calibration print for this file to help you decide how to edit the inkdescriptor file.

I must have an older version. I don't have the Curver Designer.

When you run the installerscript with the edited file a new QTR printerprofile/curve is created that you can choose from the QTR driver. After this you can linearize or make a correctioncurve for each process.

The green (CY) negatives have most contrast, Magenta-Yellow (MY) has a bit less contrast and purple CM is low contrast. You can mix in some extra yellow or magenta to finetune from the driver where you can choose two profiles and mix them.

Here is an example of my CM inkdescriptor file: CM.txt
I use the normal ink description for the first inkcolor and the toner description position for the other.

Maybe a windows QTR user can tell if this works the same on windows.
Hope this gets you on the way!

kees

In a nut shell I can turn and turn off inks throught the Curve Designer - ink descriptor file?

I suppose I need to revist QTR as I've not used it in a long while.

Thanks for the insights.

Don

 

[mkochsch]

Michael,

The Rubic's cube approach sounds interesting but I'm not sure I understand how to combind that image with QTR. Sometimes I'm a bit slow, perhaps I'm missing the obvious. But please e-mail me a copy of the cube image.

Thanks,

Don

Forget the cube. I was just describing the RGB model in broad terms. I'm not sure I fully understood what you were asking. Reading some of your other posts I think I underestimated your current knowledge base too. (My apologies.)

Where I wanted to go with this (eventually) was to point out that rather than pre-mixing the negative's "density" colours on screen using a colourised step wedge (ie. PDN) one could use QTR and do the same thing but from the back end forward. For example, with QTR you can turn off individual ink cartridges. So, for starters you can combine say the Yellow ink with the Cyan or Light Cyan to produce a green-only negative. By default QTR thinks you're printing with the "GQ" gray inkset (Generations Quadblack inks made by the company MediaStreet) but in fact we're just going to use the regular CcMmYK set from Epson without the "K". I think what you want to do to start with is use QTR to print a stepwedge for a particular process. You could make a curve from, say, Kevin Bjorke's wedge for example printed through QTR or a regular 21 step wedge. Apply the curve in QTR allowing it to be handled by the RIP instead of being applied in PhotoShop. I think QTR may accept an ACV file as a valid curve file. I think once you see the developed wedge on the emulsion you can use the QTR "Limit" function of set the density range for the emulsion paper combination.
With PDN I don't think you can really control the inks as accurately as you can with a RIP, unless you incorporate a RIP into your PDN workflow somehow. The fact is you never really know how the Epson driver is laying down the inks. However, with QTR you can make a mix of two different inksets and blend them back and forth. Say a YC and Ym combination. And each ink can have its own curve. One of my gripes with digital negatives is there are cross over areas where the inks look rough. I haven't got that far yet but I read somewhere that these can be tweaked with the QTR too.
One interesting thing that comes to mind is that you could probably make an CcMmY "All Black" negative with out using the Black (K) cartridge at all. Using a combined equal balance of CcMmY would give you nearly the full resolution of the printer without worrying about black being present if grain was an issue. It would be the opposite of epson's "Black Ink Only" print driver option. I think CcMmY might not produce a true black (probably closer to brown), but that is not important with a digital negative. What you want is the head producing many small semi transparent dots.
As a side note: I'm wondering if the Ventian Blind problem isn't just too much ink hitting the page on some of the PDN negatives. Maybe QTR can help here too. Just dial back the ink or calibrate the ink with OHP until you have just enough denisty for the process but no Ventian blinds in the highlights. Any thoughts on all this?

 

[clay]

I too think that QTR may be ultimately the best approach, since you have so much more control over the inks and how they are used. If we do get this collaborative project kicked off, what I can envision is using the RGB ternary diagram approach to determine optimal color ratios, then using the QTR curve builder routine to linearize the output from that point forward. Ideally, you could just pick a target density range QTR profile, and then print the negative without having to curve, colorize and so forth. I printed out the QTR documentation and am going to try to figure out an approach that works. I think a project like this would get the forum off on the right foot!

 

[donbga]

Forget the cube. I was just describing the RGB model in broad terms. I'm not sure I fully understood what you were asking. Reading some of your other posts I think I underestimated your current knowledge base too. (My apologies.)

Clay's post today more or less encapsulates what I was thinking about when I made my initial post about QTR. For some reason I was just drawing a blank about utilizing other colors of onks besides black and grey. Kees post jolted my memory about this; its been well over a year since I've used QTR. QUite successfully I might add make very long panoramic inkjet prints.

Where I wanted to go with this (eventually) was to point out that rather than pre-mixing the negative's "density" colours on screen using a colourised step wedge (ie. PDN) one could use QTR and do the same thing but from the back end forward. For example, with QTR you can turn off individual ink cartridges. So, for starters you can combine say the Yellow ink with the Cyan or Light Cyan to produce a green-only negative. By default QTR thinks you're printing with the "GQ" gray inkset (Generations Quadblack inks made by the company MediaStreet).

I've never heard that QTR thinks that Generations Quadblack by default. I thought it simply expected a quad or swptone inkset or a full color inkset. But that is an ancillary issue.

but in fact we're just going to use the regular CcMmYK set from Epson without the "K". I think what you want to do to start with is use QTR to print a stepwedge for a particular process. You could make a curve from, say, Kevin Bjorke's wedge for example printed through QTR or a regular 21 step wedge.

I think a 21 step sedge with a color layer would work fine for QTR since it know we are just making a digital negative.

Apply the curve in QTR allowing it to be handled by the RIP instead of being applied in PhotoShop. I think QTR may accept an ACV file as a valid curve file. I think once you see the developed wedge on the emulsion you can use the QTR "Limit" function of set the density range for the emulsion paper combination.

With PDN I don't think you can really control the inks as accurately as you can with a RIP, unless you incorporate a RIP into your PDN workflow somehow. The fact is you never really know how the Epson driver is laying down the inks.

Yes that seems correct based on my experiences.

However, with QTR you can make a mix of two different inksets and blend them back and forth. Say a YC and Ym combination. And each ink can have its own curve. One of my gripes with digital negatives is there are cross over areas where the inks look rough. I haven't got that far yet but I read somewhere that these can be tweaked with the QTR too.

That might require a lot of testing to determine if it could be tweaked. How an ink color prints also depends on the printer and the process.

One interesting thing that comes to mind is that you could probably make an CcMmY "All Black" negative with out using the Black (K) cartridge at all. Using a combined equal balance of CcMmY would give you nearly the full resolution of the printer without worrying about black being present if grain was an issue. It would be the opposite of epson's "Black Ink Only" print driver option. I think CcMmY might not produce a true black (probably closer to brown), but that is not important with a digital negative. What you want is the head producing many small semi transparent dots.

That could be useful for processes that require a very contrasty negative such as salt prints or for printers like the Epson 1800 that don't use inks that have a high UV opacity. But mixing inks like that may print a smoother negative.

As a side note: I'm wondering if the Ventian Blind problem isn't just too much ink hitting the page on some of the PDN negatives. Maybe QTR can help here too. Just dial back the ink or calibrate the ink with OHP until you have just enough denisty for the process but no Ventian blinds in the highlights. Any thoughts on all this?

I've never had the problem but I think it is printer dependent. The Epson 1800 for example doesn't exhibit this problem.

Don

 

[Kees]

If we do get this collaborative project kicked off, what I can envision is using the RGB ternary diagram approach to determine optimal color ratios, then using the QTR curve builder routine to linearize the output from that point forward.

If you look at the QTR inkseparation psd file (in the CurveDesign folder) and print it in QTR calibration mode you get 'color'scales in pure single color output. With this print and subsequent ones you choose inklimits, ink order and where each ink takes over from the previous one. In theory it could be here were a (RGB ->CMY) adapted version of your ternary image should be used and also printed in calibration mode. Maybe we can ask Roy Harrington for his insights in this matter too?

The all black no K approch mkochsch suggests is a nice idea. But probably this could be done more efficiently by using the Gutenprint (former Gimpprint) color RIP (QTR is based on GimpPrint also but designed as a B/W Rip). An all grey no K approach in QTR is working very well for digital negatives and B/W inks. I am using it for some years with MIS Ultratone (quad/hex black) inks in a no K workflow.

 

[Ron-san]

Hello, fellow "hybrids"

I too think that QTR may be ultimately the best approach, since you have so much more control over the inks and how they are used. If we do get this collaborative project kicked off, what I can envision is using the RGB ternary diagram approach to determine optimal color ratios, then using the QTR curve builder routine to linearize the output from that point forward. Ideally, you could just pick a target density range QTR profile, and then print the negative without having to curve, colorize and so forth. I printed out the QTR documentation and am going to try to figure out an approach that works. I think a project like this would get the forum off on the right foot!

I just joined APUG (see my introduction on the Hybrid site) and I have some experience with using QTR for making digital negatives. So I will plunge in and offer my nickels worth on this thread.

First point, why do you care about the color of the digital negative? In the PDN system color is the tool you use to adjust the contrast (maximum density) of the negative. But in QTR all you do is write a custom profile in which you dial the Default Ink Limit up or down until the 0% white step on your test step wedge prints as pure white on the emulsion of your choice. Sufficient negative density can be achieved with just the gray (black) inks or by a combination of colored inks, with either the Ultrachrome or K3 inksets. So, just for the purpose of negative density adjustment, color is essentially irrelevant in the QTR approach. ( and this fact alone makes QTR a more flexible tool for making negatives for printing on variable contrast silver gelatin papers).
I think the reason you want color in your negative is because Epson printers print smoother tones when they are using all of the inks. (at least this is very true for my Epson 4000). But the exact color is not important, just the fact that you are using all of the inks (I expect that the dot pattern of each ink somewhat overlaps and smooths out the dot patterns of the other inks). Here is a QTR profile (RR4000-UCmk7-OHP-Pd) designed to print negatives using all seven Ultrachrome inks (matte black) on the older OHP destined for contact printing on a pure palladium emulsion.
After making this profile, I began to read how some people think that the dark black ink prints grainier than the colored inks. I have not directly tested that notion, but just went ahead and wrote another profile (RR4000-UCmk7-OHPU-Pd) that scales back usage of the dark(matte)black ink. This profile is for negative printing using the newer Ultra OHP (although I have no personal data showing its superiority over the older stuff).
Note that these QTR profiles describe an ink curve for the dark(matte)black ink. Then they copy the dark black curve over onto the Cyan, Yellow, and Magenta inks. Similarly, the profiles describe an ink curve for the Light black ink, then copy that curve over onto the LightCyan and LightMagenta inks.

Second point, you seem to be missing a major advantage of the QTR approach. Custom QTR profiles can be written that adjust the ink settings so that the negative will print completely linear tones in the final print. In other words, you do not have to make a Photoshop correction curve to place on (and distort) the image file. Just invert the image file to make a negative, and let the ink settings in your QTR profile adjust negative contrast and linearize the midtones.

OK, OK, I admit that it is not immediately obvious how to write a QTR profile that accomplishes the above goals (although I have attached two examples to this post). Roy Harrington helped me figure how to do it, and I have written detailed instructions in a book (co-authored with Brad Hinkel) that will be published by Focal Press December 1, 2006. Sorry for the commercial, but that is where the information is located. When I wrote the book chapter I was only using dark black and light black to print negatives. Since then I have seen the advantages of using all the inks. I have written an update to the book chapter that will soon be posted on our book-related web site www.digital-negatives.com

I think QTR is a powerful approach to making digital negatives. I hope I can help those of you who want to try it out.

Ron Reeder