Please read in the instructions about Soft Proofing.
Piezography is a linear output process meaning your shadows and contrast will be different (less crunched) than if you print with an ICC profile.
That said, if you don’t want to bother with soft proofing and adjusting your image for the “linear process” of Piezography you can always print with these ICC profiles: (They will negate some of the endless shadow quality Piezo is known for, but it gets you printing in a jiffy.)
I made some tests on several supported papers with piezo pro inks on an Epson 9900 and generaly the prints are not dark and not contrasted enough. How can i corrected this knowing that we cannot do this with the print tool ?
[First, I hope I’m sufficiently recovered from jet-lag to write an intelligible and relevant post]
You’re printing with MK papers, am I right? If so I share your concerns. (This is less of a problem in my experience with PK papers and/or with high-key images.) I’ve written a blog post about the issue, although I warn you it’s a little tongue-in-cheek. It’s written that way because about a decade or so ago anyone who converted to an ICC was branded as a shadow-detail-crushing heretic. As Walker’s post indicates, the tone has mellowed over the intervening period.
The quandary I often find myself in is that not printing with an ICC results in the problem that you describe, but converting to an ICC often does indeed darken the image too much and crush shadow detail. What to do? My compromise is to apply a Photoshop curve for printing that simulates the effect of converting to an ICC, and to set the layer opacity for the Photoshop curve somewhere in the 50-80% range, typically around 60-70%. This is the technique described in the last section of that article. The Photoshop curve is derived from that second graph with the big bend in the deep shadows. You still need to soft-proof with the correct settings (preserve numbers) in order to set the percentage and protect shadow detail. I should update the final sections of that article, as I now use my own Photoshop curve rather than the Roark one.
How where they created then? My analysis of the QTR-generated ICCs is that they simulate a perceptual rendering intent of the sort that you get when printing a colour image from PS using a colour ICC and a perceptual rendering intent. That’s my understanding of the source of the problem.
Thank you Brian for all those informations ( i’ll have to read them several times ! )
I will try the different methods…i am not familiar yet with all the process…
If i understand well the 3 curves ( warm/neutral/coll) that we found for a paper in the QTR, are not iccs profiles, but curves ,! so how can i created them for a new paper wich is not supported by QTR ?
QTR ICCs only attempt to approximate a “perceptual” contrast between something like 1:250 on a monitor and the more limited print (1:160 for matte, 1:200 for gloss). They do this by darkening all the tones (even the highlights somewhat) to add a steepness to the contrast.
I studied this for a long time and found that actual iccs (i1Profiler, etc) are Tristimulus Colorimetric matching, This means they effect the relationship between the highlights and the shadows differently. The HL’s are slightly lighter than linear and this allows for light (than QTR ICC) quarter-tone shadows too (and thus more shadow detail) while maintaining the over-all contrast matching between monitor and print.
My innovation was to make full RGB profiles from simple grayscale printed targets with a method of my own creation. The workflow works for i1Profiler and any other RGB ICC program that accepts CGATS data. This workflow has been distributed with Piezography Professional Tools for over a year.
tldr: Industry standard ICC profiles make a better screen to print match than QTR-Create-ICCs. Who’d-have-thunk-it?
That depends on whether you have a measurement device like an i1Photo. If not, then you use the curves from the closest similar paper. If you do have one, then you can use it to relinearise the curves for the closest similar paper for paper you wish to print on, or you can purchase the IJM Pro toolset that allows you to create curves using your measurement device. This is a very short answer.
There are a number of risks in making another post: (i) confusing the OP; (ii) demonstrating how little I know about CM; (iii) revealing how out-of-date I am, not using either HD black, Pro inks or PPT; (iv) being reminded that one has to pay the PPT entry price in order to understand it. That all said, this issue is one that has preoccupied me for a long time, so I’ll plough on.
My (limited) understanding is that ICCs produced by the major commercial software programs contain all the four standard rendering intents, including perceptual and rel col, for both printing and soft-proofing. From what I can see, so do QTR -generated ICCs. Given this, I don’t understand the statement “… found that actual iccs (i1Profiler, etc) are Tristimulus Colorimetric matching”. I can see that the ICCs you posted do darken the image less than the QTR-generated ones. So I’m a little puzzled, and expect to remain so while I don’t have access to PPT.
@Mikemuka - I’ve done an edit to the blog article I linked to above, to simpify it and update it and to mention some of the information in this thread. You may prefer to use PPT, but there are ways to address your problem without it.