CHROMiX

Printer Ink Limits and Linearization

For the past three years, I’ve attempted to develop a suitable method for setting optimal ink limits for each media I use.
PosterShop by ONYX has recently incorporated tools and features to help their users meet this objective. Unfortunately, there appears to be no standard approach to accomplishing this task.
Are there other members of this forum who’ve struggled with this issue? And if so, what has been your experience?

Also, I have an incomplete understanding about the difference among the four density filters - Status A, Status T, DIN and DIN NB.
I’m aware of the differences based on the described standards. However, I would like to understand “why” there are different filters, and whether it matters which filter I use when creating my RIP linearization profile.

I’ve read recently on the Colorsync maliing list about determing ink restrictions by measuring chroma…finding the dot% area where max chroma is achieved. Or perhaps measuring the point where max density is achieved.

The Rip I use determines ink limitation visually…you print out an image (actually several images of varying ink amounts) and determine visually the element whose fine lines are filling in. You then choose a printer calibration file based on this. Perhaps not very scientific, but it worked for me.

Near as I can tell because they are affiliated with different standard institutions (ANSI for Status T, DIN for Satus E…with A being specific to Photographic print measurement) Why are the standards different? Same reason they use centimeters and we use inches I guess.

Onyx ink limits… my favourite.

The visual method that Onyx describes has never worked for me. I’ve use the Lch method (reading each patch with Lch values) and the max chroma method (I’m on the same list as Michael) and I like the max chroma the best. If you go by max chroma, the curves that Onyx shows you when you’re finished the linearization are very nice.

I basically set my dark ink restrictions using the max chroma method, turn back on the light inks, linearize and then ink limit if needed, before building a profile.

Except for black ink perhaps, I’ve found that measuring density on those step wedge charts doesn’t tell me anything. Taking Lch measurements and looking at chroma and hue are far more useful.

As for the filters, this is what I know:

I think status T (ANSI) is your standard north american way to measure a something reflective. Status E is used in Europe I think, and status G was something X-rite used for graphic arts applications (don’t use it unless you have a reason to). Status E will give higher density readings compared to status T for the same patch (I think). On our X-rite densitometer, we can choose to remove the effect of the paper from the density readings as well. Another variable to cause problems.

Status A and Status M are used in photo processing I believe. It’s been a while since I’ve read a control strip but I think A is for transparencies and M is for negatives.

All this filter stuff is from memory and various sources so I could be horribly wrong… don’t quote me on any of it.

Mark

Willakers!

Consistent with my technical head-banging tendency, I think I FINALLY got this rascal figured out.

However, I have made a couple of observations (consequently, provoking new questions), the causes of which I hope Steve or Mike might help me answer:

  1. Regardless of which separation setting I choose (GCR 1, 2, 3, 4 and UCR) in PM Pro 5.0.2, my gray-axis density values graph identically. Perhaps this is a positive indication of the accuracy of the PM software…

  2. The Dmax of my black ink reaches 1.69~1.70 on the fine art media I’m using in this excercise.
    However, in the density graphs referred to above, my profile Dmax only reaches 1.60 regardless of the separation setting used.

FYI…
My separation setting is 70-100-301 (CMY neutralized: ~70/75/55).
I generated and measured separate test charts for each of the five separation settings.
And, my (balanced) CMY Dmax is 1.45.

I’m not complaining about the 1.60 - that’s actually pretty respectable.
I merely want to better understand why the different separation settings appear to give me identical results, both graphically and visually (PDI-Target [PhotoDisc] image).
And, why the profiler won’t give me the higher 1.69~1.70 Dmax.

Thanks.

Just to confirm Mark’s memory:
Like he said

in photography Status A is for transmission readings (through the material) for positives like slides.
Status M is for transmission reading through negative material.
We also use R for reflective.

Now you all know more than you ever wanted to know about status codes!

Pat

At 10:33 AM -0800 1/28/05, christ0pher wrote:

  1. Regardless of which separation setting I choose (GCR 1, 2, 3, 4 and UCR) in PM Pro 5.0.2, my density values graph identically. Perhaps this is a positive indication of the accuracy of the PM software…

how are you doing these graphs? Remember that the proofing intent (device->Lab) part of a profile is unaffected by such separations settings and would be exactly the same in a bunch of different profiles from the same data but different GCR/UCR settings.

  1. The Dmax of my black ink reaches 1.69~1.70 on the fine art media I’m using in this excercise.
    However, in the density graphs referred to above, my profile Dmax only reaches 1.60 regardless of the separation setting used.

again, this depends on where you are getting the data

FYI… My separation setting is 70-100-301 (CMY neutralized: ~70/75/55).
And, (balanced) CMY Dmax is 1.45.

I’m not complaining about the 1.60 - that’s actually pretty respectable.
I merely want to better understand why the different separation settings appear to give me identical results, both graphically and visually (PDI-Target [PhotoDisc] image).
And, why the profiler won’t give me the higher 1.69~1.70 Dmax.

without knowing how you are doing your analysis I can’t really comment. Can you give us more details?

Regards,

Steve

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