QTR-Quadtone RIP

TIL means total ink limit (how much actual ink goes down per tone). Bite is how separate and defined the divits are in a gravure plate. Bite is not an issue with other types of printing. In fact, with most processes you are looking for the exact opposite (a very smooth grainless negative).

Best and cheers,
Walker


> On Sep 3, 2017, at 9:31 AM, Jon Goodman jon@jgoodgravure.com [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
> 
> 
> Please what are "TIL" and "BITE" acronyms for?
> Jon
> 
> Sent from my iPad
> 
> On Sep 2, 2017, at 6:49 PM, 'forums@... <mailto:forums@walkerblackwell.com>' forums@... <mailto:forums@...> [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com <mailto:QuadtoneRIP@yahoogroups.com>> wrote:
> 
>>  
>> To add to the density requirement variables, one must also consider the spectral range of the the UV tube/light source that is applied, the other darkroom and chemical conditions of the coating (restrainer, not restrainer, POP v dev, etc), how far the coating has gone into the paper, the paper’s sizing or lack there-of, brush vs rod, etc. All of this has an effect on the (specifically) highlight noise and stability from print to print and process to process. There is no standard here due to the infinite variables at play from one person and their darkroom process to another. More industry standard process (Ilford MG IV + Bes.23c + sprint dev) maybe could have some standards applied (indeed, Kodak has a set of density slops for their negs which are standards) but hand processes get wonky. 
>> 
>> 
>> I have found the best way to make a good negative is to do four things:
>> 
>> 1. Use many monochrome inks (similar UV response from ink to ink) that are overlapped significantly in the dense range.
>> 2. Keep the TIL even throughout the range of the negative to ensure the same bit-depth response from highlight to shadow and to allow for big stretches of the curves in shadows, mid, and highlight. This way 1 master curve will be able to print all processes from gum to salt.
>> 3. Use OHP Ultra Premium. This is the only film that can take the ink that can allow for stable highlights.
>> 4. Do some tricks to make the darkroom printed target act like a normal inkjet printed target. 
>> 
>> We did all this in PiezoDN (for about all the current epson printers besides the SureColors which we are doing something else for).  There is really no need to mess around with building new curves unless you want to mess around making your own ink-set (which some do, not faulting them). The key is to have a workflow where you can quickly and consistently get to linear printed values without noise in highlights and then be able to optionally apply a profile for screen to print contrast match if you feel like it (or don’t feel like soft proofing with a preserve RGB number workflow). That’s exactly what PiezoDN does. It’s as easy as linearizing any other curve without the initial developmental steps. And it works for literally every alt proc besides the ones that need more intense BITE like gravure (we are working on that).
>> 
>> Best,
>> Walker
>> 
>> 
>> 
>>> On Sep 2, 2017, at 12:10 PM, sanking@clemson.edu <mailto:sanking@...> [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com <mailto:QuadtoneRIP@yahoogroups.com>> wrote:
>>> 
>>> In the case of making digital negatives for alternative processes, unfortunately, the same procedure does not give the same predictable results. The fact that chemical processes do not follow a linear behaviour, sets the limits of QTR, in other words, this is not a QTR issue, it is the non-linear behaviour of the processes that limit QTR from giving you that perfect profile, so a lot of trial and error is required to obtain a fair profile that works for your specific proces
>>> 
>>> 
>>> Sidney,
>>> 
>>> Interesting post, and your experience serves to emphasize the importance of establishing density range requirements for the alternative process that reflect as closely as possible the exposure scale characteristics of the process, especially where POP/self-making is involved,  as it is with carbon transfer and several other alternative processes. If one tries to force a correction curve on a profile where the DR of the digital negative is not closely matched to the ES of the process, the result will be a very abrupt correction curve that will cause digital noise and prevent smooth transitions of tones. In cases where the DR and ES are closely matched a correction curve applied with in a QTR profile will by necessity be relatively smooth, which assured a smooth transition even with self masking processes.
>>> 
>>> The other big issue with smoothness is that it is highly dependent on the use of inks are close in UV transmission blocking and similar spectral response, especially in the critical area of the negative shadow densities, which are converted into print highlight densities. 
>>> 
>>> Sandy
>>> 
>> 
>> 
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