'hybrid' digi negs

tapering off Pk & replacing with C & Y

I'm not convinced that black ink is a problem, as long as it is used in proportionate amounts. I think it does absorb into OHP less readily, so using black could lower the max you can lay down without puddling. For that reason I taper off some of the PK and replace with C and Y for the densest couple of steps on my negs. Thus my 100% step probably looks not unlike Sandy's but with a bit of PK and LK added.

Click to expand...

I am still fairly new at QTR. I ran across this quote from Ben Altman earlier in this thread am very curious:

How does one "taper off some of the PK and replace with C & Y for the densest couple of steps"?
I'm assuming that this is written in the Gray Value part of the profile but I can't wrap my head around how it would be done.

I'm trying to create a profile (for Kallitype) which has proportionate amounts of PK, Y & C (not M) but I am finding that I need to also have Boost K to create enough contrast between 0 - 10%.

thanks for your help,
david

Hi David,

Not sure if or how one can do this with standard QTR techniques, which I have not studied in depth. However, QTR has the option of controlling each ink with its own curve (same syntax as the Gray Curve). I have written an Excel spreadsheet that generates these curves (actually have evolved this over several years). I think others also do this to generate custom QTR profiles. I'm working on making this user-friendly enough to publish as a shareware item that can be used to generate quick and accurate profiles for any process. Still ironing out the details...

If you want to see what is going on inside your QTR profiles (on Mac) you can open the .quad file as a text file and look at the individual ink profiles. I guess one could figure out a routine for editing that, but I have not looked into it.

Best, Ben

Ben Altman said:

If you want to see what is going on inside your QTR profiles (on Mac) you can open the .quad file as a text file and look at the individual ink profiles. I guess one could figure out a routine for editing that, but I have not looked into it.

Best, Ben

Click to expand...

The .quad files are human readable text files though who knows what the values mean to the RIP.

Wouldn't we want to read and edit the .qdif files? Or perhaps I'm missing something (which wouldn't be the first time).

Don

david drake said:

I am still fairly new at QTR. I ran across this quote from Ben Altman earlier in this thread am very curious:

How does one "taper off some of the PK and replace with C & Y for the densest couple of steps"?
I'm assuming that this is written in the Gray Value part of the profile but I can't wrap my head around how it would be done.

I'm trying to create a profile (for Kallitype) which has proportionate amounts of PK, Y & C (not M) but I am finding that I need to also have Boost K to create enough contrast between 0 - 10%.

thanks for your help,
david

Click to expand...

Using black boost, I believe, is pretty typical of most QTR curves. All of my curves are using the black boost to get those last few squares dense enough. My current kallitype curve has a pK limit of 19 and a black boost of 38. I have the limit on Y set to 15 and I just throw in a little C to fill in.

PM me if you want and I'll email you the curve I'm using for kallitype. You can use it for comparison or see if works for you.

Don Bryant said:

The .quad files are human readable text files though who knows what the values mean to the RIP.

Wouldn't we want to read and edit the .qdif files? Or perhaps I'm missing something (which wouldn't be the first time).

Don

Click to expand...

.quad is Mac, .qdif is Windows, as I understand it. Have not worked with the latter.

In a .quad file each ink is represented by 100 numbers, which vary from zero to something around 12,000 typically. Zero means no ink, big numbers mean a lot of ink. Would be easy enough to write a profile with one ink only to see what the numbers translate to on the user side of the interface. I just tried opening a .quad profile in TextEdit, changing some numbers and re-saving as a .quad - seemed to work fine. So this could be a way to fine-tune a profile. Would be kinda trial and error, though - would need to set up a spreadsheet and chart the numbers to keep the profile smooth. In older versions of Excel you can grab the points on the chart and adjust them. Newer versions you need a plug-in (Windows) or write your own (Mac). Grr.

Ben

R Shaffer said:

Using black boost, I believe, is pretty typical of most QTR curves. All of my curves are using the black boost to get those last few squares dense enough. My current kallitype curve has a pK limit of 19 and a black boost of 38. I have the limit on Y set to 15 and I just throw in a little C to fill in.

PM me if you want and I'll email you the curve I'm using for kallitype. You can use it for comparison or see if works for you.

Click to expand...

hi rob

From my understanding, Ben was saying that he does not use the K boost but he tapers off the black before the densest areas and just uses yellow/ cyan for the densest area. The reason being is that K does not absorb into the OHP as readily as the colors. He was also trying to keep the colors proportionate ( as far as UV absorption) By keeping them proportionate, you seem to avoid the grainy look. So, his technique seems opposite that k boost. More like Y & C boost.
I'm trying out the proportionate approach to see if it will have smoother and cleaner tones (especially in the highlights) and having a high K boost, I would think, works against that.

david

You are following my thinking, David. In my current profiles for Pd there's still some PK and some LK in the last few steps, but quite a lot less than Y and C. You should test with your OHP material to see which inks it takes the best. And if you can get to paper white with unbalancing the proportions of the inks, I'd go for it.

Best, Ben

I've just started working with PDN knowing very little about digital negatives. Working through the calibration and testing process really taught me a lot about the negatives and what was necessary to achieve the desired results. IMO it's a lot of work regardless of the process or tools used. Not more work than I'm willing to do but one has to commit to the work to achieve good results. I did get a good print the first time through, not where I want to be but good enough to get me excited about the process and possibilities.

I think it's important to use the process and tools that you are comfortable with. The results are what's important.

~Bill

Ben Altman said:

... And if you can get to paper white with unbalancing the proportions of the inks, I'd go for it.

Best, Ben

Click to expand...

Oops! Should read "without unbalancing..." Sorry!

Ben