Digital BW, The Print

I think you have missed the essence of QTR Create ICC. QTR with a QTR profile is not a straight line density function. The whole point of developing QTR Create ICCC was to address this very fact. I'm not sure that the forums archives go back far enough but if you were around in '05 you may recall the conversations in which I was a significant protaganist which led Roy to develop Create ICC. Until then, people using B&W rips (including QTR) were indeed applying a linear density function to their prints and this lead to issues such as shadow compression and complaints of "overall lighter prints" than on screen. Draw a straight line between an imperfect black and an imperfect white and it's obvious this is the result. Roy brought gamut mapping to the B&W world by applying techniques long used in the colour domain for black (and white) point compoensation.

Epson was aware of the issue of applying a linearised density ramp to a print when they made ABW. They embedded non-linear gamut mapping in ABW but of course hard-coded it to the selectable Epson ink and paper combinations. Roy's QTR Create ICC was a better solution. It allows the technique to apply to any ink and paper combination (not just Epson) and, of course, for any individual printer. It has significant add-on benefits including the ability to preview images with their 'colour' toning on screen and to be able to post or send an image in digital form with this 'as when printed' toning. When applied to Epson ABW printing it improves this as well.

All the best

Steve

On 29 Jan, 2015,at 04:05 PM, "richard@richardboutwell.com [DigitalBlackandWhiteThePrint]" <DigitalBlackandWhiteThePrint@yahoogroups.com> wrote:

In response to the comment on the "just use ABW" from the "another drawback of coated paper" thread:

Earlier last year I was asked to write a few chapters on printing for a digital black and white book, and started making comparisons with different printing methods. The book project fell through, but I had the tests done and made the following blog post a few days ago along with scans of actual prints and density measurements: http://www.bwmastery.com/blog/2015/abw-vs-qtr

I realize that some people see the the straight line curve as a drawback of QTR, but I see it as a huge benefit. By controlling how much more ink goes into the shadows and still having them separate you can have the appearance of dark/rich shadows that smoothly transition into pure black, rather than a noticeable jump like moving up the black point with a levels adjustment. This QTR approch has a similar visual affect to a gamma 2.2 adjustment, but doesn't crunch and compress the last bit of shadows. It does require controlling the tones in the original file and not using a blanket correction curve, but the resulting prints look almost identical to the screen and don't usually require additional ICC profiling or color managed printing. I also realize that you can create ICC profiles to correct for some of the problems with ABW, but if you are going to do that you might as well make your own (or use) QTR profiles and create ICC profiles for them instead.

I am now writing a post about comparing prints made QTR and Epson K3 inks, QTR with Eboni-6 and my QTR profiles, Piezography Carbon K6 prints I made, and Selenium and Warm Neutral K7 prints that Jon Cone made for me last year as comparison prints to use in the book. It might take a few weeks depending on how work projects go though.

Richard Boutwell